public health journal 22 (2011)

Public Health Journal No. 22 April 2011

INSECTICIDE-TREATED MATERIALS Many different textiles found in homes, community areas, clinics, and refugee camps can be converted into highly effective vector control tools by using insecticide-treated materials. Such ITMs, as well as the proven highly effective bednets, can provide high coverage for protection against vector-borne diseases, particularly malaria. But it is not enough to distribute these ITMs. They have to be used consistently and become a routine part of daily life.

PUBLIC HEALTH JOURNAL 22/20112 |

C o N T E N T

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Editorial

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Gap between ownership and use of long-lasting insecticidal nets

Creating a “net culture”by Hannah Koenker

C o v E R S T o R y

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B E H A v I o R C H A N G E

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16Workshop organized by Bayer and AED

How to increase LN usage

NetMark studies and interventions

Promoting the use of ITNsby William D. Shaw and Carol Baume

Background

Insecticide-treated materials: Current challenges and future perspectivesby Gerhard Hesse

PUBLIC HEALTH JOURNAL 22/2011

k E y f A C T S

INSECTICIDE-TREATED MATERIALS (ITMS) FOR VECTOR CONTROL

Adding insecticide to mosquito nets and using them at high level coverage transformed them from personal protection into a real vector control tool. Other successful examples include curtains to control dengue and leishmania vectors, and outdoor traps to control tsetse flies. Another major aspect related to high

Prevent infective bites by avoiding contact between the vector and the person sleeping under the net.

Insecticide-treated netting (ITN)Polyester nets, coated with a long-lasting (wash resistant) polymer/insecticide matrix (e.g. K-O TAB® 1-2-3).

Long-lasting insecticidal nets (LNs)Polyester nets, industrially coated with pyrethroids. Wash resistant polyethylene nets with active ingredient included in the fiber.

LNs with improved durability Polypropylene as stronger material with active ingredient included in the fiber.

BEDNETSTreated tarpaulins and tents for displaced people after civil unrest, wars and natural disasters. Coated with a long-lasting (wash resistant) polymer/insecticide matrix.

TARPAULINS AND TENTS

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Existing home textiles can be converted into a vector control tool by treating them with an insecticide.

CURTAINS/ROOM DIVIDERS

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EAVE LININGS

Available as poster on the enclosed Public Health CD-RoM

INSECTICIDE-TREATED MATERIALS (ITMS) FOR VECTOR CONTROL

coverage is the development of resistance against the overall used pyrethroids, being the ideal class of insecticides in terms of application, stability and safety. The search for other modes of actions and other active ingredients is on, including their use on plastic sheeting, eave linings, etc.

Polypropylene material as woven flat yarn with incorporated deltamethrin. Fixed to the walls and ceiling of houses or huts. Positioned to replace conventional indoor residual spraying (IRS).

DURABLE WALL LINING

Treated materials that simulate by shape and color a target host (cattle) for the tsetse flies. The materials treated with insecticides (pyrethroids or insect growth regulators) reduce the population by killing or interrupting the development cycle.

TRAPS AND TARGETS

Normal treated netting material which closes the gaps between the walls and roof of houses – a frequent entry point for mosquitoes.

Treated polypropylene surfaces fixed to house walls used by mosquitoes as preferred resting sites. A bendiocarb treated version is undergoing scientific trials in Africa.

PLASTIC SHEETING


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P R o G R A M P L A N N I N G

42

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Cover photo: Michelle Cornu

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Physical tests and durability of bednets

Simulating ageing, wear and tearby Severine Huchet

Insecticide-treated curtains (ITCs)

An effective method for dengue control?by Philip McCall

Resistance matters: New publication on IRM 52India: Malaria deaths underestimated 53LifeNet: Strong and effective 54WHoPES: Setting standards for safe use 55Book review: The Fever 56Malaria: Human parasite from gorillas 57

HistoryLeishmaniasis 58

CD-ROM 59

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Physical test results on three different mosquito nets

Different strengths and weaknessesby Severine Huchet

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The cost and cost-effectiveness of bednets to prevent malaria

A tool for comparisonby Claudia Wolff, Anni-Marie Pulkki-Brännström, Jolene Skordis-Worrall

R E S E A R C H & D E v E L o P M E N T

Alliance for Malaria Prevention (AMP)

Protection for everybody

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N o T E S

4 | PUBLIC HEALTH JOURNAL 22/2011

This edition of the Public Health Journal addresses a number of timely concerns amidst positive news about efforts to control malaria. According to the WHO World Malaria Report 2010, enough insecticide-treated mosquito nets have been provided

over the past three years to protect 578 million people at risk of malaria in sub-Saharan Africa. And about 42% of African households now own at least one insecticide-treated mosquito net.

However, surveys in the field alarmingly reveal that many nets are not being used correctly, or even at all. Our cover story discusses many reasons for this gap between ownership and net usage, and suggests possible strategies for developing a necessary “net culture” in malaria-risk communities.

In addition to distributing nets, maintaining effective net coverage in the future is vital, but also poses many problems and questions. How long does an insecticide-treated mosquito net remain functional in the field? How robust are long-lasting insecticidal bednets to general wear and tear? What are the costs of regular net replacement? Such questions are investigated in our program planning and research and development articles. Within this context we introduce our LifeNet, designed for long durability in the field. A new inclusion technology for treating multifilament polypropylene netting material has resulted in a net that is compact, strong, and resilient, with slow-release of insecticide (deltamethrin). This increases its wash resistance and effective life span. All these factors contribute to reducing costs incurred by bulky shipment distribution cycles, and regular net replacement programs.

Without doubt, control measures are protecting more people against vector-borne diseases, with insecticide-treated bednets being one of the most effective vector control tools against malaria. Indeed, with recent developments a whole range of materials have similar potential. Insecticide-treated curtains to control malaria, leishmania and dengue vectors, and outdoor traps to control tsetse flies are already in use. A major challenge is to preserve the essential functions of such insecticide-treated materials now threatened by increasing insecticide resistance.

We wish you pleasant reading. Gunnar Riemann

e d i t o r i a l

Member of the Bayer CropScience Executive Committee and President of

the Environmental Science Division Worldwide

PUBLIC HEALTH JOURNAL 22/2011 | 5

Diseases which were recognized as problems during the 18th, 19th and early 20th century are still present and in some cases thriving. Dengue fever, chikungunya, Leishmaniasis, and other vector-borne diseases are moving north or south (in the southern hemisphere) due to climate change, infecting people never before exposed to such tropical diseases (see PHJ 19). For instance, France last summer reported the first indigenous cases of dengue. On the other hand, the main component of the tool kit, the chemical control measures are under threat from insecticide resistance development, regulatory issues and other factors – so the arsenal is dwindling. This makes integrated vector management (IVM) increasingly important.

Within the context of IVM and the latest technologies, which have become available over the last few years, the use of insecticide-treated textiles or fabrics has become extremely important. The best example is the improvement of the long-known mosquito net by adding insecticide to promote it from being not just a personal protection tool but also a vector control tool with a potential mosquito population effect when adequate coverage is obtained.

Around this principle a whole range of different textiles have been developed or are under development – all following the same goal of being a vector control tool (see cover flap). First, a short introduction into nomenclature:

• Functional textiles: a very broad term, but mostly used in relation to a textile that has to play a specific role, not just as clothing or carpets, etc.

•Health textiles: already more specific in the sense that the basic function of the textile is related to

supporting health or preventing health risks, like hospital clothing having anti-bacterial properties, textiles to prevent mosquito bites, etc.

• ITM: a general abbreviation for insecticide-treated materials in the sense of textiles, not exactly specifying their use, e.g. as a bednet or a

tsetse fly target.• ITN: insecticide-treated netting qualifies the type of fabric, nowadays mainly used for formerly

plain nets, which are treated by the user with an insecticide in the home or in the field.

• LN: long-lasting pre-treated bednet, whereby the long-lasting characteristics follow WHO guide lines.*

A functional textile in vector control should prevent the contact between vector and a person and in best case kill the vector.

Suitable home textiles, which are widely available, can be converted into a vector control tool by treating them with an insecticide. Philipp McCall highlights the use of treated curtains for such use in this issue of PHJ (see page 42). WHO/TDR is

Current challenges and future perspectivesInsecticide-treated materials (ITMs) are among the most effective and widely used tools for protecting against vector-borne tropical diseases, particularly malaria. Despite the high expectation placed upon them in terms of achieving high coverage, we must also ensure that their essential function in vector control is maintained.

insecticide-treated materials

b a c k g r o u n d

The author: gerHard HeSSe

Head of Global Partnering Vector Control,

Bayer Environmental Science, Lyon, France

* Guidelines for laboratory and field testing ofLNs: http://whqlibdoc.who.int/hq/2005/WHO_CDS_WHOPES_GCDPP_2005.11.pdf

b a c k g r o u n d


conducting significant field studies on the use of curtains for various disease cycles. The Bill & Melinda Gates Foundation are funding trials including curtains as an IVM tool in their Casa Segura project (see PHJ 19, page 26).

Displaced people after civil unrest, wars and natu-ral disasters often find themselves crowded in refugee camps. As always under such conditions vectors thrive and transmission of pathogens finds an easy field. Treated tarpaulins and tents are ITMs used in refugee camps. A durable wall lining to replace conventional indoor residual spraying (IRS) is the newest tool under investigation. The one model introduced onto the market is a polypropylene woven material treated with deltamethrin. This wall lining is fixed to the walls and ceiling of the houses or huts with the intention of covering the whole surface. By that and the assumed residual effect it is positioned to replace conventional IRS.

A comparable principle, but more related to use as an insecticide resistance management (IRM) tool, is using a so-called eave lining or insecticide-treated plastic sheeting. The advantage is that the treated material only partially covers the walls (around the eaves or on vertical surfaces) and can be positioned as replacement for indoor residual spraying. Used with a pyrethroid-treated bednet at the same time and treated with non-pyrethroid active ingredients it becomes the resistance management tool. Bayer is working with IRM on a bendiocarb based model that can be used in areas with pyrethroid resistance. Field trials have shown a vector population reduction and impacts on the disease.

Treated traps and targets to control tsetse flies outdoors are a commonly used tool (see PHJ 21, page 32). Depending on the insecticide used and the device planned, there are catch-and-retain, attract-and-kill, or catch-and-sterilize-and-release devices. The last two can be treated with deltamethrin, and/or sterilizing IGR triflumuron.

Concentrating on treated bednets, with special emphasis on LNs, technology has progressed tremendously over recent years. For treated bednets the internationally funded market has stimulated the

development of new long-lasting technologies from simple in field dipping of plain nets (e.g. K-O Tab® 1-2-3) to industrially coated polyester nets followed by polyethylene nets where the insecticide is in the fiber.

What does long-lasting mean? Unfortunately, WHOPES testing could not confirm a longer lifespan for the finally recommended net materials in the field for more than three years. This means that net distribution campaigns need to be repeated after every third year. This is a logistical nightmare, not only in difficult to access areas, but in general, not even taking the needed replenish ments of lost, worn out, destroyed, burned nets, etc. into consideration.

Meanwhile, the international aid community requests the development of even better products in the sense of improved durability. Physical strength parameters that can be measured with ISO approved tests in the laboratory are defi nitely one aspect (see page 30). But meanwhile it is accepted that factors of daily use of the nets probably play the major role – such as misuse for other purposes like the famous fishing net, handling too close to a fire, dragging over sharp objects, impact of domestic animals, etc. So besides having the physically strongest net, education of how-to-use and treat nets is also important.

To meet all these challenges Bayer is taking a multi-pronged approach:•Developthephysicallystrongestnet - based on a new strong material, polypropylene, - attach to it the convenience of a soft touch (multifilament), - and use the strongest pyrethroid as active ingredient (deltamethrin).•Developeducationalconceptsforthepeopleto make them use the nets.•Developeducationalconceptsforthepeopleon how to use the nets.

The first task has already been achieved with the development of LifeNet, which is under WHOPES Phase II evaluation at the moment. One specification in the positioning, besides the general use as a true

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long-lasting net (more than three years in field to be confirmed by WHOPES Phase III), will be to have an answer for programs in difficult to access areas due to topography, remoteness, or whatever other features. It is common understanding that a longer lasting net in the field has a higher value for money compared to a shorter lasting net. To prove that assumption a working group of the Health Economics and Financing Program of the London School of Hygiene and Tropical Medicine has developed a model that allows developing scenarios with costs and health impacts for various long-lasting bednet types (see page 25).

The campaign to support increased usage rates of nets started with a first workshop (out of three) with experts in behavioral change, communication, program implementation, etc., held in Washington DC in April 2010 (see page 16).

With the development of resistance to commonly and repeatedly used active ingredients, the question is what role can ITMs play? In theory they can play a crucial role, being one of the most used intervention types in vector control with a huge coverage, e.g. LNs in Africa. In practice it is not that easy; because of their chemical, physical, biological and safety characteristics, the insecticide class of synthetic pyrethroids is the ideal class for the purpose. Unfortunately, the biggest problem with resistance, in the context of malaria vectors, is with synthetic pyrethroids. Equally unfortunately, the other chemical classes are not well suited for the treatment of textiles, due to application dose rate, water solubility, temperature stability and safety aspects.

With the other big malaria vector control inter-vention, indoor residual spraying, rotational use of non-cross resistant insecticides is widely used, e.g. rotating bendiocarb with pyrethroids (see PHJ 18). First attempts in the use of LNs were made by incorporating PBO (piperonyl butoxide) into the net, but without the required results. New modes of action are under investigation such as pyrroles and carbamates. Tackling issues such as speed of action, mortality, safety, etc. – again there is nothing like pyrethroids and bednets. But smart formulations

might overcome restrictions and the future will tell if ITMs can be used for resistance management.

In terms of IRM, the “mosaic approach” is more promising: one still uses a pyrethroid treated bednet but the eave linings or partial wall coverings are treated with bendiocarb that kills pyrethroid resistant mosquitoes while entering the room or resting on the wall. Results from the “Institut de Recherche pour le Développement” (IRD) have proven that the principle is basically working.

Rotation of different insecticide mode of action groups is an option in the other major malaria vector control intervention method (indoor residual spraying) and has been adopted widely of late (e.g. integration of bendiocarb into a rotation with pyrethroids in IRS programs). First attempts to adopt different modes of action in LN’s have been made by incorporating the synergist piperonyl butoxide into parts of the net but results are not yet conclusive. Other insecticide groups such as pyrroles and carbamates are under investigation. Speed of action and safety are key attributes which must be taken into account and very few of the currently available active ingredients achieve the same level of performance as pyrethroids. Smart formulations may help overcome some of the limitations of alternative chemistry however and the future will tell if ITM’s incorporating non-pyrethroid insecticides will be considered valid resistance management tools in the future.

The effective and safe use of functional textiles is proven in the case of insecticide-treated materials for vector control in tropical diseases. This has led to a high coverage, e.g. with LNs, which is threatened now with the increasing development of resistance against pyrethroids as the one and only used insecticide class. As other chemical classes are not suitable per se in the same way as pyrethroids for various reasons, the R&D driven public health industry is in full swing to find alternatives or smart formulations to preserve the unique value of ITMs in vector control.

concluSion

Long-lasting insecticidal nets (LNs) can reduce

malaria infections and save lives. But merely

distributing nets is not enough unless they are

used consistently and correctly. Unfortunately,

in malaria endemic regions large gaps still

exist between ownership and use of LNs. This

cannot be solved simply by instruction on

using nets and explaining their benefits.

Additional communication interventions must

aim at creating a “net culture”. Only when LNs

become a routine part of daily life can we

ensure sustainable net use.

Creating a “net culture”

Gap between ownership and use of long-lasting insecticidal nets

c O v e r s T O r y


NeT cOverAGe should be scaled-up from children under five and pregnant women to include the whole population. According to the WHO 2010 World Malaria report, 23 countries in Africa have now adopted the WHO recommendation to provide nets to everyone at risk of malaria.


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The barriers

Fortunately, we know a fair amount about barriers to use, once nets are in the home. Nets are used more often in the rainy season than in the dry season, when mosquitoes are less noticeable. The jump in net use in Niger’s rainy season, for example, is remarkable – from 15.4% to 55.5% for children under five.3 In Senegal, using a calendar of net use in a recent post-campaign survey, net use varied from less than 30% in the dry season to nearly 80% in the rainy season4, with comparable rates in Burkina Faso.5 In other countries, the variation can be similar. But it is not simply the

presence of rain that is influencing behavior – mosquitoes emerge in great numbers from the puddles, and nets are used to avoid nuisance biting as well as malaria.6,7

Access to nets also plays an undeniable role. The more nets in the household, the more likely it is that a child under five will be sleeping under one.2

Physical factors like sleeping space arrangements matter: Sleeping inside and outside during the night, shifting sleeping arrangements within households, and sleeping near kitchen areas are important determinants of use.8,9 Repositioning nets throughout

the day and evening is an inconvenience that can overcome even the best of intentions. Some nets are not long enough to reach underneath beds, or they are too confining. In addition to these structural factors, fears and attitudes play an extremely powerful role, but one that is hard to quantify. Some users are afraid of the insecticide8, and feelings of hotness or claustrophobia are common.10,11,12,13

Unfortunately, large-scale household surveys only rarely include questions on reasons for not using nets, exposure to IEC/BCC (see box) messages through their various channels, and other ques-

alaria is one of the leading killers of children in Africa. Worldwide, half the global population, 3.3 billion people, are

at risk of infection. Just under one million people die each year from the disease. Along with effec-tive treatment, indoor residual spraying, and pre-vention of malaria in pregnancy, long-lasting insecticidal nets (LNs) are one of the key tools in the fight to reduce malaria deaths to zero.

Treated bed nets have been distributed in mass campaigns since 2002, often coupled with inte-grated child health campaigns. Tens of millions of nets have gone out to families at risk. These nets can reduce malaria episodes by 50%, and save 5.5 lives per every 1000 distributed.1 But while enormous efforts have focused on getting the nets into households, the data have shown a significant gap between ownership of nets and their consistent use.

Among net-owning households, the gap has been measured as the difference in the overall percentage of households that own one or more nets, minus the percentage of those households in which a child under five slept under a net the previous night. When the global goal was to prioritize children under five and pregnant women, it made sense to only report on their sleeping habits. But now, with the goal set at universal coverage, there is a need to measure and report net use for every member of the household.

A review of the gaps between ownership and use in fifteen countries in 2008 found that in house-holds that owned one or more nets, the rates of use by children under five the previous night ranged from 27% (Zimbabwe, 2006) to 71% (Kenya, 2003).2 What explains the gap?

M

The author: HANNAH KOeNKer

Senior Program Officer for malaria control,

Johns Hopkins University Center

for Communication Programs (JHUCCP),

USA


tions that would help illuminate the relative impor-tance of all these barriers. Smaller scale studies can explore the issue in-depth, but only the house-hold surveys give us the power to determine what the most pressing issues are, and how our messag-ing can affect them.

so what can we do?

Two types of strategies have been employed to resolve these barriers: structural interventions (assisting with hanging up of nets; changes in the net itself) and communication interventions.

Over the last few years, a few improvements have been made in the nets themselves. The push towards scale-up of net coverage, first for under-fives and pregnant women, and now for the gen-

eral population, has meant large procurements and a practical inability to deliver nets that match the consumer’s preference. This gives little incentive to donor agencies to procure anything more than a standard rectangular net. Those who prefer rectan-gular get round; those who prefer round get rect-angular; the color may not be their favorite; per-haps they would have preferred a fancy border. Overall, we have little data to suggest that not get-ting a net in-line with one’s preferences has any effect on use. A study in Mozambique showed only a few percentage points less usage in groups that received the net they did not prefer.14 Nets are valuable commodities and useful whether they are square or round or white or blue. Nonetheless, tak-ing user preference into account in the design of nets is important. Recently, most manufacturers have lengthened the nets to accommodate

c O v e r s T O r y

IEC and BCCIec: Information, education and communicationIEC is a process of working with individuals, communities and societies to: • develop communication strategies to promote positive behaviors that are appropriate to their settings.

Bcc: Behavior change communicationBCC is a process of working with individuals, communities and societies to: • develop communication strategies to promote positive behaviors that are appropriate to their settings; and• provide a supportive environment which will enable people to initiate and sustain positive behaviors.

What is the difference between Bcc and Iec? Experience has shown that providing people with information and telling them how they should behave (“teaching” them) is not enough to bring about behavior change. While providing information to help people make a personal decision is a necessary part of behavior change, BCC recognizes that behavior is not only a matter of having information and making a personal choice. Behavior change also requires a supportive environment. Community and society provide the supportive environment necessary for behavior change. IEC is thus part of BCC while BCC builds on IEC.

Source: UNESCO

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consumer desire for taller nets. And improvements are underway in durability of the bottom edge, which gets tucked and untucked under mattresses or mats repeatedly throughout the net lifespan. Home visits to assist families in physically hang-ing the net have come to be viewed as a central component of net distribution. Families may lack string, nails, a hammer and other materials needed to attach the net. On the other hand, families who are motivated to use their nets often find solutions with materials at hand, like strips of rags woven together to make a rope for hanging. Is the value of the hang-up visit the physical hanging assistance, or the communication accompanying the visit on the importance of sleeping under the net? Or even

the sense that using the net is a community-sanctioned action; a social norm, carrying the weight of peer pressure? Unfortunately, hang-up visits vary from country to country (and year to year), and quality of training and implementation probably makes more of a difference to whether the visits are successful than the mere fact of visiting a house. Studies are attempting to find the answers to these questions.

A study from Burkina Faso noted explicitly the role played by the sleeping space and the shape of the room and house on net use. “Bednets were not used when the perceived benefits of reduction in mosquito nuisance and of malaria were considered not to be worth the inconvenience of daily use.”15

So how to reduce the inconvenience, in situations where nets must be put away and re-hung each night, or hung near cooking fires where the chil-dren sleep to stay warm, or in a multi-use space that may be a salon during the day and a sleeping area at night? Not to mention in environments where a portion of the night one sleeps outside, then moves indoors.

FAMILy INsTrUcTION IN TANZANIA outside their home, where the use of bednets is explained by a trained local volunteer.

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Innovative net modifications

One way would be to increase the convenience, by adapting the net itself to the conditions, changing the hanging mechanism, making it easier to put away, or more resistant to tears and burns. Second, we might look to users themselves for innovations in hanging and storing nets. Community volun-teers conducting hang-up campaigns have likely seen some inventive ways to solve hanging prob-lems. Their experience could be harnessed to inform revised volunteer training manuals, to assist in diffusion of the innovations. In Senegal and in other countries, a number of households have been observed where square nets were turned into “round” ones by simply attaching a round object – a bicycle wheel; the lid of a large plastic bucket – inside the roof of the net. As procurements continue to supply a standard net across a given country, local tailors and/or community groups could be trained in net modification techniques, and offer these as a service to the community.

Besides increasing the convenience of the net, we can increase the perceived benefits of mosquito and malaria reduction. By making mosquitoes and malaria more unacceptable, the perceived nui-sance of using the net is actually reduced.

The same principle applies to those who “misuse” nets – the farmers and the fishers16 and families using nets as wedding veils. Those who misuse nets perceive a greater benefit from using the net for fishing/agriculture/resale, etc., than for pre-venting malaria, or preventing bites. Increasing the perceived benefit of using the nets for malaria prevention – or even just a good night’s sleep – so that this benefit is greater than the benefit of being able to fish with the net, or protect seedlings, would flip the balance. But there are no easy answers.

NeT sUrvey IN NOrTH eAsTerN KeNyA Home visits find families motivated to use their nets, often solve problems with innovative solutions.

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Knowledge, attitudes, practices

Newcomers to the net use problem often look to increase knowledge as a first step. Clearly, people not using their net cannot know how useful it is! They must not know that mosquitoes cause malaria; they need to know more, and then they’ll use their net every night. Right?

In a word, no. Knowledge is an important part of behavior change – it’s often the first step along the path to change. But while it’s necessary, it’s not sufficient to change behavior. We all know malaria experts who seldom sleep under nets, or take pro-phylaxis, despite being extremely knowledgeable about the risks. Some studies show that knowledge is not significantly correlated with use;17,18,19,20 others show that it can be associated with increased net use.21,22 Once knowledge reaches 80-90%, however, it is time to look for other factors to work on to improve net use.

Beyond knowledge, one’s own attitudes and social norms are vital influences on behavior. One’s sense of risk of getting malaria and the conse-quences associated with illness, combined with one’s sense of self-efficacy at preventing infection, and confidence in the net as a tool that does pre-vent malaria, are also important.

community level engagement

Data from Tanzania23 show that community level activities emphasizing the risks of malaria, and what to do to prevent it, had a remarkable effect on survey respondents’ perception of risk and their sense of self-efficacy. Those exposed to the cam-paign had increased levels in both categories. This then correlated with increased net use by all chil-dren under five in households that had participated in the activities.

In order to shift social norms towards using nets all year round, communities and their leaders must be on board. In Senegal, during the recent univer-sal coverage distribution, community leaders developed their own communication plans,

THe OUTsIDe Use OF NeTs is an alternative when sleeping indoors is to warm or takes up too much space. Local tailors or community groups could be trained in net modification techniques and offer these services.

A TrUcKer IN seNeGAL demonstrates a practical solution to sleeping under a net when on the road.

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We should challenge ourselves to measure both the determinants of use, and the impact of our behavior change communication (BCC), and to share the results to promote lessons learned, both good and bad. We must continue to build capacity to identify and address barri-ers to net use, particularly as countries reduce their malaria burden and move towards sus-tained control, in a lower-risk environment. Taking advantage of high levels of donor funding to improve net use now, to build self-sustaining habits, is our unique opportunity.

cONcLUsION

Article with full list of references on the enclosed Public Health cD-rOM.

assembling panels to speak on the radio, conducting household visits, even threatening check-ups to make sure families were using all their nets, and talking of taking unused nets away. While their zeal may be a bit much, the message they are sending is clear: Net use is not just a household issue, it affects the entire community. Tailored education messages coming from community leaders in Tanzania were effective in increasing rates of net use.24 It is vital to work through these community leaders, who are capable of shifting social norms from their positions as respected figures. Can we work with communities post-distribution not only to promote net use throughout the year, but also to monitor and track nets to inform planning? Continuing to engage communities and their leadership after campaigns are over will be paramount.

Net culture

Communities that have been using nets since long before the advent of the ITN are said to have a “net culture”. But what exactly is a “net culture”, and how does a community acquire it? Practically, it is where untreated nets have traditionally been used; but really, it is where net use is expected normal, and seen as protective or beneficial in some ways (and not necessarily for malaria prevention, or even to avoid nuisance biting – nomadic groups in Mali use thicker opaque nets when they sleep out-side, for privacy). How can we promote “new” cultures of net use? Can we tie nets into key transi-tion moments in life – as wedding gifts, or board-ing school requirements? In the era of universal coverage, we are called on to promote nets for all ages. The opportunity is there to use nets as incen-tives not just for pregnant women to attend antena-tal clinics and for under fives to get their immunizations, but also to promote girls’ education, for example, for women attending family planning services, or ongoing adult or workplace health programs.

As scale-up efforts progress, we must continue to think about communication in the context of low transmission settings – either because the area has historically low prevalence, but more often, we hope, because control efforts are succeeding. When the risk falls ever lower, thanks to our suite of control interventions, how can we keep net use at high levels? Since net use now seems to be driven at least in part by one’s perception of risk, we should take the opportunity now to create hab-its that will continue even when the risk of malaria is reduced.

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NeTs should be a part of everyday life.

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growing, and as malaria cases reduce, so will usage. When NetMark (see link on page 20) asked family members why they did not use their nets some said that nets were unnecessary because there were few mosquitoes, or they did not regard malaria as a serious illness. Some questioned the effectiveness of the product or said that the net was hard to hang, in poor condition, or did not meet their preferences for design, shape, size, and color. Nets were also stored and saved or used for other purposes such as room dividers.

African families are the key to the solution. That means taking their concerns seriously and realiz-ing that there is no “one size fits all” solution. Different cultural dynamics, value systems, and personal perspectives require tailored approaches. Segmentation within the household must also be considered. The perceived values (benefits) of a

he workshop focused on the fact that long-lasting insecticidal nets (LNs) have achieved

a wide coverage, but nevertheless are quite often used incorrectly – or even not at all. Working in small groups, coordinators and participants investigated reasons for this and considered possible solutions. The participants included program managers, malaria experts, net producers, and behavior communication specialists.

The goal of this workshop was to create a community that uses innovative thinking tools to refresh the views on existing challenges, and create an open discussion to be continued at other venues. At the same time, the participants wanted to increase their knowledge about the reasons for non-use of LNs. Ultimately, the aim was to develop ideas for measures and strategies that could improve LN usage.

outlining the problem

Several studies in Africa indicate that the 30% to 40% percent of nets distributed are used inconsis-tently, incorrectly, or not at all. The percentage of households who have nets but do not use them is

During the week preceding World Malaria Day 2010 (April 25), Bayer and AED* held a one-day workshop in Washington, DC. Participants were representatives from private sector companies, government agencies, and non-governmental organizations enga-ged in malaria control. The meeting discussed ways of increasing use of LNs from multiple perspectives with the goal of developing fresh approaches.

How to increase LN usage

Workshop organized by Bayer and aeD (academy for education Development)

T

* AED (Academy for Education Development) is a nonprofit organization working globally to improve education, health, civil society and economic development. In collaboration with local and national partners, AED fosters sustainable results through practical, comprehensive approaches to social and economic challenges. AED implements more than 250 pro-grams serving people in the USA and more than 150 countries.



product will differ for the father or mother. An example came from family planning projects where economic values were found to be much more important to the man and health values were perceived as being more important to the woman. For nets, it must also be considered that one per-son may be more influential in the acquisition of the product and another for its use.

Systematic inventive Thinking

The workshop introduced participants to Systematic Inventive Thinking® - SIT, an inno-vation methodology regularly used within Bayer Environmental Science to assist teams to see existing challenges in a new light. Participants learned about the SIT approach to problem solving (UDP Mapping) and identifying new user benefits (Attribute Value Mapping). The workshop also encouraged participants to see issues from different angles and long-term perspectives, build a common understanding, look for micro solutions, explore ideas for data collection and analysis and learn how to communicate in ways where the value or benefit of the bednet is very clear in the mind of users.

The workshop introduced participants to a cognitive phenomenon called “Functional Fixedness”. “Functional fixedness” limits a person to using an object only in the way it has been traditionally used, thereby preventing that object being used in a different way to solve a problem. The group was challenged to look at the resources that are available in the problem world and to innovate using these; what SIT calls “thinking inside the box”. SIT’s approach to problem solving, involves creating a “chain of undesirable phenomena,” and finding places where we can break the chain and solve different aspects of the problem.

The process requires:

• Creating a chain of ‘undesirable phenomena’ that is a cause and effect scheme of the problem. The chain starts with the undesirable situation one wants to address, referred to as the “anchor”,

and builds upward by asking “so what” questions and builds downward by asking “why” questions. Each link in the chain describes what an element of the problem is doing and why this is problematic. A solution that breaks one of the links will eliminate the undesired effect, but not the one below it. Anything above that link will be resolved.

• Taking an inventory of resources from the closed world of the problem that could potentially be used to as a resource to solve the problem.

• Applying an SIT tool to start working towards a solution.

applying SiT to the use of Lns

The workshop anchor was defined as: People at risk of getting malaria who have acquired nets are not consistently sleeping under them. Elements that help explain why people who have nets aren’t consistently sleeping under them include:

• Malaria is not perceived as a serious threat.• Lack of knowledge among consumers.• People who are respected are not advocating for

the use of LNs.• LNs are not the norm.

Product-related elements include:

• Size doesn’t fit in the room.• It’s hot and uncomfortable to sleep under the net.• Perceived risk of the insecticide.• Ineffective (won’t work).• Hard to use.• Better uses for the net.• Doesn’t match personal preferences such as

color.• Prefer saving the net for later use or perhaps to sell. causal chains

Participants divided into four groups were pre-sented the task of creating a causal chain focusing on one problem. They then had to find places where the chain could be broken by thinking



The ParTiciPanTS oF The WorKShoP included program managers, malaria experts, net producers, and behavior communi-cation specialists.

group 2People think insecticide-treated nets are ineffectiveDespite using LNs people still get malaria. Mosquitoes landing on nets still live and people don’t see dead mosquitoes on their nets. Here, one has to concentrate on whether bednet use is consistent, and that nets deter and then later kill the female mosquito seeking a blood meal. Also one must counteract the messages of key influencers who claim that nets are ineffective, by:• Shifting the focus from killing mosquitoes to controlling malaria.• Tailoring the messages about nets to different regions.• Changing donor paradigms so donors focus on consumers.• Advocating for better market research.• Creating a multi-purpose net, for example one with pockets and put interesting things in them.• Making nets that are appealing and associated with fun.

group 1People don’t perceive malaria as a riskIn many communities malaria is only one of many other serious and immediate issues and is considered no worse than a common cold. The difficulty here is persuading people that something can be done. Often mosquitoes are not associated with malaria; they are few in number, and not everyone gets severely ill or dies. Possible solutions to such barriers are:• Use information, education, and communication to educate that mosquitoes transmit malaria.• Increase the perception of malaria as a serious risk. • Use culturally acceptable and trusted individuals to convey messages.• Link mosquitoes with malaria even when mosquitoes are few.• Link malaria with other pressing issues.• Increase the number of non-malarious mosquitoes during the dry season.• Promote nets for benefits other than protection against malaria.

differently about elements in the boxes and using them in a new way to solve the problem. The themes addressed were: why people don’t perceive malaria as a serious risk; why they think insecticide-treated nets are ineffective; that people

lack information; and that nets are not being hung (see boxes on the next pages). Each group reported back to the larger group to discuss possible solutions to these problems.



attribute value Mapping

The workshop went on to make the distinction between attributes and values. Mapping out values and attributes helps identify messages for effective communication. Attributes are objective, described using nouns and adjectives, and refer to a product, e.g. effective, safe insecticide; inexpensive prevention. Values are subjective, described using verbs and adverbs, and refer to the individual. They can be summed up by the phrase “What’s in it for the user?” E.g. child won’t get sick and die; you won’t miss work. After creating the map, the attributes and values that are focal points of a large number of connections should be examined, as they potentially hold the key messages that should be communicated.

clear call for action

Often malaria communications lack a clear call for action. For example, are nets to be used only in the rainy season? Are they for everyone or only for children under five and pregnant women? Positioning a product first as appropriate for a child may make it difficult later to include adults as users.

The call to action also needs to be consistent. If messages call for the baby to be under the net (protect your family) and alternatively say that productive members of the household should be under the net (avoiding malaria allows you to be more productive and thereby benefit you economically) the contradicting call for action in these messages may dilute their overall impact.

group 4nets are not being hungThere are many reasons why people do not hang up nets, e.g. they have no way to affix them (nets are not flexible in terms of hanging requirements), the ceiling is too high, house type and room space not suitable, etc. Possible solutions are:• Produce the “perfect” net: light weight material, durable, ease of installation in different types

of house, easy to get under and out of the net, connectable panels, flexible, poles that can fold in and out, pockets.

• Develop a trademark.• Redefine the cost:benefit relationship by calculating the manufacturing, software, and

implementation costs and determining how many people can get under the net/dollar.

group 3 People lack informationIf one is unaware of something or set in a traditional mode of thinking and action, it can be difficult to adopt new practices. Often people have no knowledge, or insufficient exposure to knowledge. Messages about bednets may be unclear or unconvincing. Possible solutions are: • Tap into non-health benefits.• Communicate benefits that resonate with the consumer (and not just from the public health

perspective) using clear and convincing messages communicated frequently through multiple channels.

• Use the target population to sell the benefits (examples: peer education, media, opinion leaders, donors, schools, churches).

• Tailor messages about nets to different audiences.• Present convincing data to donors to use resources for community activities and communications

to address non-use.• Increase number of stakeholders who can pay for diffusion of information.



New groups were formed to list different attributes and values of LNs, with some of their suggestions summarized below:

Attributes of LNs Effective (active ingredient kills mosquitoes)Safe.Physical barrier. Value: Protects child from malaria!Child won’t get sick or die.Child is happy and playful.Child will grow and develop normally.Child won’t miss school and will be better able to learn.

Attributes of LNsInexpensive prevention.Long-lasting. Durable. Effective. Value: Saves money / improves income!You won’t miss work because you or your child is sick.You won’t miss work because your family is healthy.You won’t lose productivity (wages, chores) because you’re sick (or, you’ll be more productive and earn more because you’re healthy).You’ll have reduced costs for medicine and health care.

Attributes of LNsEffective and safe insecticide.Physical barrier that keeps mosquitoes and other pests from biting and transmitting diseases. Value: Keeps you healthy!You’ll be protected from malaria, fever, and other diseases.You’ll sleep better.You’ll be more comfortable because you aren’t suffering from bites. You’ll live in a pest-free environment.

The good news is that positive change can hap-pen. The workshop challenged participants to use tools such as SIT to facilitate problem solving, explore ways of using existing resources to create positive change, reconsider one’s assumptions, collaborate with others in finding solutions, and be open to change. Solutions were proposed that included types of messaging and product design changes. The key message that came out of the event was that messages must be tailored to different seg-ments right down to understanding the dynam-ics of decision making within a household and ensure that communication forming the Call to Action is not contradictory.

concLuSion

article on the enclosed Public health cD-roM.

Don’t forget malaria in asia

One feedback comment from the workshop added the important point of not forgetting malaria in Asia. Indeed, although not generally as lethal as Plasmodium falciparum, P. vivax still threatens nearly three billion people, mostly in central and southeast Asia. The 2009 global atlas published in the open access scientific journal PLoS Neglected Tropical Diseases shows how this continues to be a relentless threat to locals and visitors, particularly due to growing resistance to antimalarial drugs.

More

AED: www.aed.orgNetMark: www.netmarkafrica.orgPublic Library of Science PLoS Neglected Tropical Diseases: www.plosntds.org

b e h a v i o r c h a n g e


he NetMark1 project is a ten-year effort to build sustainable commercial markets for

ITNs in Africa, funded by USAID and implemented by the Academy for Educational Development (AED)2. Operating in seven African countries, NetMark’s household surveys began to reveal that many families were not using all the nets in their households.

To understand the problem better, in late 2007 NetMark conducted a study on the non-use of ITNs in Ethiopia, selecting 857 households for interviews and in-home observations. When similar non-use patterns appeared in Ghana and Nigeria and were reported by malaria programs in other countries, in 2009 NetMark designed and launched a pilot campaign in Ghana to find a cost effective way to address the non-use of ITNs.

NetMark was among the first groups to recognize that a lot of ITNs were lying unused in many homes. This happened particularly in areas where there had been mass distributions of ITNs with little communication to promote their importance, value, and nightly use. It has conducted studies and campaigns to find ways to address non-use of ITNs in Ethiopia and Ghana.

Promoting the use of ITNs

netMark studies and interventions

T

1 NetMark represented a time-limited investment by USAID to reduce the burden of malaria in sub-Saharan Africa by increasing the commercial supply of and public demand for insecticide treated nets. This was achieved primarily through partnerships with commercial companies and national malaria control programs, and national scale public education and promotional efforts. More: www.netmarkafrica.org

2 AED is a nonprofit organization working globally to improve education, health, civil society and economic development – the foundation of thriving societies. In collaboration with local and national partners, AED fosters sustainable results through practical, comprehensive approaches to social and economic challenges. AED implements more than 250 programs serving people in all 50 US states and more than 150 countries. More: www.aed.org

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iTn PrograMS in Ghana increased net ownership in households with pregnant women or children under five from 29% in 2004 to 71% in 2008.


eThioPia

iTn ownership and use

Net ownership in Ethiopia has increased dramati-cally in recent years with the mass distribution of 20 million ITNs to 10 million households. Household ITN coverage in the targeted, malari-ous areas increased from 6% to 65% (2007 Malaria Indicator Survey). NetMark’s Use Study in the Oromia and Amhara regions showed that 91% of households had at least one ITN, with an average of 1.8 nets in net-owning households. The vast majority (84%) of nets were LNs handed out by the government and NGOs.

Conducted during the malaria season (October), the study revealed that only 65% of nets were used by someone the night before. It also showed that nets that were purchased at full or subsidized prices were

more likely to be used than free nets (76% to 63%). Surprisingly, it also revealed that 16% of nets in these households had never been used.

barriers to net use

The main barriers to optimal net use cited by these families are listed below. No percentages of respondents are given because the research was qualitative, and sometimes several barriers were mentioned in a single family.

Malaria is not a problem: While 44% of respondents reported that someone had malaria in the past year, those respondents were clustered geographically, with some other areas reporting 13% of malaria cases. In some areas, malaria is epidemic, and recedes as a major problem in the years between epidemics.

Few mosquitoes are around: There is a general belief that nets are needed only after the rains when there are many mosquitoes.

ITN is no longer effective: The effectiveness of ITNs in repelling and/or killing mosquitoes may be perceived as declining over time as fewer mosquitoes come to the net, or when repeated washing or the accumulation of dirt on unwashed nets limits the insecticide’s power. People may also feel that their net needs to be retreated.

Rectangular nets don’t fit traditional round houses: They may take up too much space or be difficult to repeatedly put up and take down. The 2007 Malaria Indicator Survey found that use of LNs was 1.6-fold greater in households that owned conical nets compared to those that owned rectangular nets. Not enough room in the house for more than one net: One net may take up much of the living space in a small home.

Nets are hard to hang: The structure of the house may make it difficult to hang nets, particularly rectangular ones, over all sleeping spaces. The nails used to hang them may easily pull out of mud walls.

ethiopia

The authors: WiLLiaM D. ShaW,

caroL baUMe

Academy for Educational Development (AED), Washington, USA

Phot

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Nets are in poor condition: Many nets had holes or tears; some were very dirty.

Some nets “saved” for the future … or for future sale: 16% of nets were still in their pack-ages. Some entrepreneurs followed the mass dis-tribution teams to buy up the free nets distributed.

Some nets used for other purposes: Some nets were cut into pieces to cover valuable property (e.g. tv, radio) or used as room dividers, ceiling covers, curtains, and table cloths. These behaviors were not common and tended to occur in specific areas when someone’s new idea was copied by others.

ghana

iTn ownership and use

Ghana has had a multi-faceted ITN program that used a combination of free distribution, discount voucher and other subsidy programs, and commercial. This has increased the proportion of households owning one or more ITNs from 3% in 2003 to 33% in 2008. NetMark’s household stud-ies that sampled only households with pregnant women or children under five showed net owner-ship increasing from 29% in 2004 to 71% in 2008, with the percentage of ITNs among nets owned jumping from 31% in 2004 to 86% in 2008.

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MaSS DiSTribUTion of 20 million ITNs to 10 million households has dramatically increased net ownership in Ethiopia.



The NetMark study, however, also showed that three out of four nets had been used the prior night in 2004; but as net ownership increased, the percent of nets used decreased to 59% in 2008. Nets that were acquired free of charge were used

less (55%) than nets that had been paid for (68%). Given the fact that data on the non-use of nets were emerging from many countries, NetMark decided to design and implement a commu-ni cation intervention to see if it could

develop a replicable model that would have a significant impact in increasing the use of ITNs already in the home.

increasing the use of iTns in the home

NetMark staff in Ghana conducted baseline and formative research on net use issues, which led to designing an intervention that employed mobilizing community volunteers, information dissemination via mobile vans that showed a video presentation, and a malaria-based drama presented by live theater groups. The Net Use Intervention (NUI) was evaluated using a scientifically sampled cohort of houses in the region, conducted between its launch in June 2009 and its conclusion eight weeks later in August in the intervention (Gomoa East District in the Central Region) and control communities.

The impact of the interventions was evaluated by comparing indicators of net ownership, net use and knowledge of malaria transmission between the intervention district and the control district. The post-test survey showed no change in knowledge about ITNs in either Gomoa or the

article on the enclosed Public health cD-roM

ghana

control district, since almost all residents had already heard of ITNs. In terms of ITN use the previous night, 73.6% of the households in the control area reported using a net at baseline, increasing to 79.9% at post-test surveys. The corresponding figures for Gomoa were 63.9% at baseline and 84.4% at post-test, demonstrating a strong and statistically significant intervention effect.

This promotion of net utilization succeeded well beyond the planners’ expectations. Initially, it was deemed that the 8-week intervention would be the minimal necessary to have an impact. However, as the weeks passed, it became clear that the com-munities had become more than convinced that nets were necessary, and instead of just promoting usage the intervention was dramatically increasing demand for new ITNs. In the final two-three weeks of the campaign, professionals and volun-teers alike were bombarded with requests to increase the supply of new ITNs, an intervention feature that had not been planned. Thus, nearly 10,000 new nets were sold at subsidized rates to the intervention communities during the last week of the intervention.

Net ownership, especially ITNs, has increased dramatically in Ethiopia and Ghana over the last few years, but so has the proportion of unused nets per houshold. Similar non-use patterns are being reported by malaria pro-grams in other countries. NetMark studies show that ITN distrubution needs to be accom-panied by interventions to promote their use.

concLUSion

p r o g r a m p l a n n i n g


istributing malaria nets has proven to be a highly efficient way to reduce malaria

morbidity and all cause of child mortality. The WHO (2007) is now calling on all actors to invest in long-lasting bednets (LNs) and in full coverage rather than targeted campaigns. However, purchasers may be put off by the higher unit cost of long-lasting nets and may be uncertain about the cost-effectiveness of long-lasting nets in their context.

In this article we present a tool for modeling LN cost and cost-effectiveness. The aim of this tool is to enable the user to explore for themselves how the adoption of LNs might impact the cost-effectiveness of their country programs. Here, we describe the tool and use a snap shot to illustrate what the tool might be capable of showing.

This tool builds on the work of Lengeler, Yukich and Kilian (see: Public Health Journal No. 21, page 48). Kilian provided a comprehensive list of WHO-recommended long-lasting nets and

By filling in a number of variables, program planners can compare the potential costs and benefits of long-lasting net distribution with/without replenishment in their context. This article explains how to use the tool and illustrates the results for an intervention spanning a 10-year period.

A tool for comparison

The cost and cost-effectiveness of bednets to prevent malaria

D

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described a long-lasting net as one that has an 80 percent probability of passing “the strict criteria for mosquito knock-down and killing” after three years. Lengeler and Yukich used five country case studies to explore how LNs can improve efficiency and cost-effectiveness of vector control. In addition to these two articles, the work below draws on a comprehensive review of the literature on the cost effectiveness of bed nets to prevent malaria.

overview of the tool

The tool is an Excel-based spreadsheet that requires no special software or advanced knowledge of Excel to run. The user is able to compare up to three scenarios. Within each scenario the user can input a range of variables to ensure the scenario is relevant to their context. The snapshot of the tool below demonstrates the input fields.

Beginning with the choice of net, the user can specify up to three net options. Each net is



characterized by price and expected lifespan as shown in Table 1. Note that while the tool allows the user to set the lifespan of a net at under three years, insecticide retreatment costs are not permitted in the tool. The measures of cost and cost-effectiveness described later in this article would be derived from calculations that assume these nets are replaced at the end of their lifespan, or have no effectiveness after that time.

Each scenario then requires information on the number of bednets distributed, population in the distribution area, number of children under 5 within the population, assumed usage rate, number of people using the net, the number of under-5s using the net and the procurement overhead. These are referred to as “free fields” in the discussion below since the user is able to choose any value for these variables.

Drop-down menus assist the user in selecting the region, primary distribution method, mark-up for international transport costs, replenishment rate and method of replenishment.

From input to results

Of the free fields, program planners are likely to have little difficulty in specifying the number of nets, population, and procurement overhead. However, the usage rate and number of people per net should be specified with caution, since these are key measures of program effect. Usage rate is

THE USEr specifies the scenario using the “free fields” and drop-down menus on the right.

Table 2

Scenario specification

Number of nets distributed

Population in distribution area

Number of children under 5

Total average usage rate

Average usage rate among children under 5

Average number of people per net

Average number of under-5s per net

Distribution method

Include CIF/FOB mark-up on price?

Procurement overhead (US$ total)

Replenish nets on an annual basis?

Distribution method for replenishment

250,000

1,000,000

200,000

30%

50%

2.0

0.40

Free distribution integrated to routine services, large scale

Yes - 1.44 (sub-Saharan Africa)

50,000

Yes - replace 5% each year

Free distribution integrated to routine services, large scale

region: rest of africa – stable endemic risk (Class 4)

priCE anD EXpECTED liFESpan for three different long-lasting nets

Table 1

long-lasting net options

Net 1

Net 2

Net 3

5

6

7

3

4

5

price (US$) net lifespan

(years)



* http://www.who.int/choice/costs/price_multiplier

commonly measured by asking a sample of people whether they slept under a (treated) bednet the previous night. The average usage rate is high if:

• the number of nets distributed is large relative to the population;

• individuals with access to a net use it regularly.

The choice of region facilitates comparison of the number of deaths and disability-adjusted life years (DALYs) averted by campaigns facing different malarial risks. However, this variable is not intended to capture the full complexity of regional differences in malarial risk and program effectiveness. Instead, this tool uses a baseline with a multiplier that attempts to capture differential risk. In the baseline, 5.5 deaths are averted for every 1,000 children under 5 protected by bednets (Lengeler, 2004). The following multipliers are used: 1 for low risk (Class 1), 1.08 (deaths) and 1.04 (DALYs) for low stable or epidemic risk (Classes 2 and 3), and 1.92 (deaths) and 1.97 (DALYs) for stable endemic risk (Class 4). The multipliers are derived from Snow et al. (2003).

The user is given a choice of distribution methods. These include free campaign distribution, free distribution integrated into routine services (small or large scale), or subsidized sales supported by social marketing. This choice determines the distribution cost per net. The values assigned to each method by the tool are derived from previous studies of bednet cost-effectiveness and calculated in 2009, in US$. This is the method used by Yukich et al. (2008). The distribution cost ranges from US$ 1.45 per net for large-scale free integrated distribution, to US$ 3.86 for subsidized sales and social marketing.

The mark-up on price is intended to capture international shipping costs that may not be included in the purchase price of nets. The mark-up varies between 25 and 44 percent as suggested by WHO-CHOICE.*

Replenishment is not often considered in studies of bednet cost-effectiveness. However, while the re-treatment of LNs may no longer be necessary, in the years between distribution rounds, coverage may still fall due to damage or misuse. In this tool, the cost of (annual) replenishment is included in total program cost, unless the user chooses not to invest in replenishment. The benefit of investing in replenishment is that the number of people protected does not fall between main distribution rounds, however total program cost is higher than without replenishment. By specifying two scenarios, one that includes replenishment and one that allows coverage to fall between distribution rounds, the user can see the effect of replenishment on cost-effectiveness.

results

Populating the tool using the scenario in Table 2 enables the user to compare the cost and cost-effectiveness of the intervention, using the three LNs in Table 1. A snapshot of these cost comparisons is provided in Table 3 and the cost-effectiveness in Table 4 (see next page).

In this example, Table 3 shows the cost savings of nets 2 and 3 compared to net 1, as well as the annual cost per net and the cost of replenishment in each case. In this instance, and over a ten-year time horizon, net 3 is the most cost-effective

The authors (from left to right): ClaUDia WolFF,

anni-mariE pUlkki-BrÄnnSTrÖm, JolEnE SkorDiS-Worrall

University College London, UK



choice despite being the more expensive net. Note however, that changing any parameter in Table 1 or 2, may yield quite a different result. For example, if the price of net 3 is US$ 8 instead of US$ 7, net 2 is the more cost-effective in this scenario.

In this scenario, 100,000 children are protected each year and 10,571 under-five deaths are averted over 10 years. For this scenario then, the model estimates that 356,198 DALYs are averted over 10 years.

article and full list of references on the enclosed public Health CD-rom

All of the parameters in this tool are sourced from the literature, drawing on the most recent evidence in the field. However, as with any modeling exercise, assumptions have been made and a complex reality simplified. LNs are relatively new to the market. As they are increasingly rolled out, more and better information is likely to emerge. Despite its limitations, this tool allows donors, governments and other users to compare the cost and cost-effectiveness of different bednet distribution programs. The tool plays an important exploratory role, prompting users to consciously consider the different components of program costs. Different scenarios might illustrate how higher net prices may be offset by higher program benefits or lower distribution costs. This is done using the best available evidence.

ConClUSion

ComparaTiVE CoSTS of the 10-year program distributing and replenishing net 1, 2 or 3 in the scenario outlined in Table 2.

Table 3

Comparing costs

Cost (US$)

Total cost

Procurement cost

Primary distribution cost

Replenishment distribution cost

Cost savings over 10 years, compared to net 1

Annual cost per net

net 1

7,762,288

7,576,437

1,275,638

95,466

-

3.10

net 2

7,304,717

7,302,250

970,739

110,711

457,571

2.92

net 3

7,051,781

6,251,100

675,193

125,488

710,507

2.82

ComparaTiVE CoST-EFFECTiVEnESS of the 10-year program, outlined in Tables 1 and 2.

Table 4

Comparing cost-effectiveness

Cost (US$)

Cost per person protected

Cost per under-5 protected

Cost per death averted (under 5)

Cost per DALY averted (under 5)

net 1

2.59

7.76

734

21.8

net 2

2.43

7.30

691

20.5

net 3

2.35

7.05

667

19.8



A new tool for comparison

The cost, cost-effectiveness and impacts of lns onmalaria control programs

Distributing long-lasting treated bednets has proven to be a highly efficient way to reduce malaria morbidity and child mortality. Since 2007, the WHO has been calling on all actors to invest in LNs, with a goal of universal coverage. However, stakeholders may be confused by the variety of LNs available, their evaluated WHOPES durability versus the advertising claims of the supplier, the different prices, different distribution models, incl. replacement or not, etc. All these parameters have an impact on program costs and the cost-effectiveness of long-lasting nets in their specific program area.

Bayer has developed a concept applying a new tool for modeling the LN cost:benefit ratio. The aim of this model was targeted to enable the program implementer, donor, or project owner to explore by themselves how the adoption of LNs might impact the cost-effectiveness of their country programs. The tool was then built in close collaboration with the University College London (UCL), Centre for International Health & Development, to explore the value proposition of LNs in Malaria control programs (see article on page 25).

overview of the tool

The tool is a web-based database that requires no special software or advanced IT knowledge to run. The user is able to compare up to two scenarios. Within each scenario the user can choose a range of variables to ensure the scenario is relevant to their contextual environment (number of nets distributed / population in the area, number of children under 5 using nets, epidemiological back-

ground, etc.). The second scenario can be run to compare impacts on the program costs, e.g. by having different replacement rates, distribution schemes, coverage rates, etc.

Cost:benefit ratios

Since all of the parameters behind the variables are based on published and grey scientific literature, the scenarios reflect more accurately a simplified complex reality. We confirm that this tool allows donors, NGOs, implementers, and other users to compare the cost and cost-effectiveness of e.g. different LN products, or distribution and replacement programs under different epidemiological and user conditions. For example, different scenarios illustrate that with a higher price / unit for a new generation, more durable bednets (such as LifeNet) do not increase program costs over time. The new more durable nets make less distribution cycles and replenishment schemes necessary over a period, and so decrease program costs, and increase the positive impact on disease parameters such as “cost / death averted” and “cost / DALY averted”. These scenarios can be compared to the LNs with max. 3 years durability evaluated by WHOPES for the current products. So donors should not be fixed on criteria like lowest unit price, but rather sustainable control over a selected time period.

This tool is available (upon consultation with Bayer CropScience) to work out your specific program in all details. As a do-it-yourself tool, a web-based tool will be made available from the Bayer Global Vector Control website to be launched in May 2011.

r e s e a r c h & d e v e l o p m e n t


he following article presents the various physical tests that can be performed on nets.

Some are “classics” for the textile industry, while others are less common but specifically apply to mosquito nets. Not all of them are part of the WHO/JMPS specifications for LN1. Secondly, additional modified physical tests are explained, since these could be used to predict the durability of mosquito nets and are referred to as accelerated ageing treatments.

traditional textile tests for strength and durability

Physical strength is usually an important property for textile applications and there are two types of test: the burst test and the tensile strength test. The former is used on knitted fabrics, while the later is for woven fabrics, and therefore not appropriate for nets. The abrasion test with some variations is used to test durability.

Mosquito nets combat malaria not only by providing a physical barrier between people and mosquitoes but also by killing mosqui-toes that come in contact with the nets. Many studies and work have gone into improving the effectiveness of the nets from a chemical point of view. However, little is known about the physical properties of these nets, and pre-dicting the durability of a mosquito net is an important but challenging question.

Simulating ageing, wear and tear

physical tests and durability of bednets

Burst test: for strength The principle is to measure the resistance of a fabric to bursting using a pneumatic diaphragm. A test specimen is held between circular clamps, and then the fabric is subjected to slow and continu-ously increasing pressure from a rubber diaphragm until it ruptures (see Fig. 1 and 2). The bursting resistance of the fabric is the pressure reading at the time of rupture. The test is repeated without the sample and the pressure subtracted from the first reading. The test is performed five times, and the result is the mean bursting value or the average height of the “bubble”. The test can be carried out on a 7.3 cm2 or 50 cm2 sample size, but the test results from two different sample sizes are not comparable.

By expanding and stretching in 3D, this test measures not only the strength of knitted fabrics but also their tear strength.2

TPhoto: Albert Kilian



Clamp

Liquid

Piston

Rubber diaphragm

Specimen

Pressure gauge

0

50100 150

200

250

Abrasion test: for durability Abrasion is very often associated with the durabil-ity and performance of a product for apparel and in technical textiles. Abrasion is the ability of a fabric to withstand damage by repeated friction. The principle involves rubbing a sample of fabric against a standard surface in a repetitive controlled motion. There are different abrading machines but the most widely used is the Martindale.3 The fabric is placed on top of a circular clamp and gently placed on the standard surface, also called the abradant, where the rubbing takes place. The top clamp rotates in a so-called Lissajous movement (see Fig. 3).

clamped over a rUBBer dIaphraGm, pressure on the specimen fabric is slowly increased by a piston compressing liquid to expand the diaphragm until the fab-ric ruptures. The pressure gauge reading at the time of rupture gives the sample resistance to bursting.

the test FaBrIc stretched over a pneumatic rubber diaphragm inside the pressure chamber.Fig. 1

Fig. 2

1 Source: Manual on development and use of FAO and WHO specifications for pesticides, 2010. 2nd revision of the first edition.2 This test is fully described under the ISO 13938-2: 1999 or ASTM D 3786-08 test methods. ISO = International Organization for Standardization (European standards). ASTM = American Society for Testing and Materials (US standards).3 Martindale: described under the test method ASTM 4966-98: 2007.

Burst tester close up view of a bursting test

lIssaJoUs movement that starts as an ellipse and ends in a straight line rubs the specimen fabric mounted on the sample holder across the fixed abradant surface. This movement should cover all areas of the sample and does not favor any direction so that it is considered “random”. 1 cycle = 16 revolutions (or rotations, or rubs) needed for the full Lissajous movement. Older testers abraded in a single direction (for example, a pendulum swinging over a sample a thousand times). The complex movement is considered a great improvement.

Fig. 3

martindale abrasion test

Backing felt

Standardabradant

Foam backing

Sampleholder

Sample

Spindle

Top plate

Load12 kPa

or9 kPa



Fraying and attrition are the two most applied kinds of results obtained from an abrasion test (visual assessment and color change are also possible).

Fraying: The abrasion process continues until the fabric is visibly partly destroyed. The number of rotations is recorded. For woven material: destruction of two threads. For knitwear: destruction of one thread causing a hole to appear. In the case of mosquito nets, it could be agreed to be until one branch of one hole is opened. Fraying is easy to compare since it is a number that can be averaged. However, there is a risk of human error if the technician does not see the hole.

Attrition: is the loss of weight of the sample. First the sample is weighed, then a certain number of rotations are agreed upon in advance, for example 4,000. Weight loss is plotted after 1,000, 2,000, 3,000 and 4,000 rotations. This is repeated eight times and averaged. In this case the results are graphs, not as easy to compare (in comparison to fraying), but very interesting, because it shows the “life” curve of a fabric, and helps predict how the fabric will behave over time. Some fabrics do poorly in the beginning, but then “stabilize” and do just fine for many more rotations.

A combination of both tests is used to determine the number of rotations needed to come close to the fraying point, and then the attrition test is run again using 25%, 50%, 75% and 100% of this value.

specific tests for mosquito nets

When developing a new product, depending on the application and its intended use, additional tests are performed on fabrics to better evaluate their chance of survival in the field. These tests are either a standard test, but most of the time, they are slightly modified to better mimic the real wear and tear on the product. For mosquito nets several tests are possible, for example a variation of a rip test

also known as the slow nail test, the dynamic nail test and the ball burst test.

Slow nail test: for slow ripping resistance The slow nail test, or “Nadelaus-reißkraft DIN4 54301”, was developed in Germany and there is no equivalent in the US standard books of methods, only in-house tests. This test measures the resistance of the fabric to breaking (or ripping) after a foreign object penetrates the fabric. This is not to be confused with a tearing test (which is not appropriate

for knitted fabrics and totally different). A nail test will simulate a rip. If something can get caught in the net and starts pulling down (such as rings, children’s fingers or bed splinters), then the net must resist and not rip apart.

This test is performed on a universal tensile tester, where the bottom clamp is replaced by an open clamp device with a hole. A nail is inserted through the clamp hole and one hole of the net fabric, then the bottom clamp starts pulling down. The test measures the force needed to tear the fab-ric with the nail (see Fig. 4).

The author: severIne hUchet

Consultant on textile testing and quality control, NC State

University, College of Textiles, USA

4 DIN = Deutsches Institut für Normung (German standards)

a naIl Inserted through a hole in the bottom clamp of a universal tensile tester pokes through the net fabric (blue circles). The bottom clamp is pulled down, and the required force and sequential resistance to tear is measured as a series of peaks and troughs (depicted by black squiggly line).

Fig. 4

slow nail test

Top clamp

Bottom open clamp with hole and peg

NetFabric

Nail



The force curve has many peaks and troughs, since varying resistance is encountered while pulling down. Usually the first or highest peak, or the average of the three highest peaks is recorded.

Dynamic nail test: for tearingThis test is a French standard test (NF G 07-147). Although it starts like a ripping test (with the nail carefully inserted in between net holes), there is a dynamic movement that tears the net in half, in a split second. So this test could almost be considered as a tearing test. This equipment allows recording only one result, which is the maximum strength at breaking. This test is similar to a bed splinter getting caught in the net while pulling to fold away the net for example, or a goat/rodent/chicken eating and pulling on a net (see Fig. 5). This is a very versatile test, and the ball device can

easily be exchanged by other shapes, such as coni-cal or flat objects, larger spheres, or even a dagger. This could mimic an elbow poking through the net while the net is tightly tucked under the mattress.

Recommended amendments to the WHO/JMPS specifications for LNAn abrasion test is not part of the WHO/JMPS specifications for LN (see box on the enclosed Public Health CD-ROM). A Martindale abrasion test could become a recommendation with a minimum of 16,000 rotations performed before the net frays (15 frictions per day, every day, for 3 years). Differences between multifilament yarns and monofilaments may have to be considered.

The two nail tests are also missing from WHO recommendations. They both are very important tests because many things get caught in the nets. Most of the holes appear from ripping accidents and not from washing.

Comfort and breathability under a net are also very important properties. This is not addressed in the WHO recommendations but could be. Although comfort is subjective, some work has been per-formed in the area of comfort, for example at the Textile Protection and Comfort Center (T-PACC), at the College of Textiles, North Carolina State University (USA).

Ball burst tester

Fig. 6

a metallIc polIshed Ball is continuously pushed against the sample fabric securely clamped on a traditional universal tensile tester. The equipment mea-sures the force required to rupture the fabric surface, the displacement and the energy at maximum force. Other shapes can be used, for example a blunt dagger to mimic an elbow poking through the net.

Ball burst test: for strength Another burst test that measures the resistance of a fabric to bursting due to a foreign object is described in ASTM D3787. The specimen is securely clamped without tension on a circular clamp and a metallic polished round ball, usually 1 inch in diameter, is continuously pushed against the sample until the fabric ruptures. The result is expressed as the force required to penetrate the surface, the displacement and the energy at maxi-mum force. It is performed on a traditional univer-sal tensile tester (see Fig. 6).

dynamic nail test

Fig. 5

Sample

Fixed nail

Clamp

a sample oF FaBrIc, pierced by a fixed nail and held by its extremity in a clamp connected to the pendulum impact tester, is subjected to sudden traction.



predicting the durability of a net: accelerated ageing methods

Current WHO requirements for LNs are to survive three years in the field and 20 washes. New LN entries (like the polypropylene net from Bayer) like to set new standards with five years survival in the field and more than 35 washes. While it is easy to wash a net 20 or 35 times, it is not practical to wait three or five years on a small-scale trial to verify whether the net actually survives. Therefore, it is important to develop accelerated ageing methods that will provide critical information before launching a new product. All the treatments described below will fatigue nets in a controlled and repeatable way. These treatments are modified standard physical tests that should closely mimic real life wear and tear conditions. After being aged, a performance test such as a burst test or a nail test should be performed. Comparisons of before/after, as well as “new net” vs. “WHO approved nets” will give valuable information about a new net’s chance of survival in the field. Ageing treatments applied to a net include: cyclic bursting, cyclic tensile, stone washing, snagging, abrading, and of course multiple washes.

Cyclic burst treatmentThis is performed using either the ball burst tester (see Fig. 5) or the pneumatic burst tester (see Fig. 1 and 2). Instead of carrying out the test until the fabric ruptures, pressure is applied in cycles. A first test is performed and then a percentage of this burst pressure is applied (push-pull or inflate-deflate) repeatedly on the same sample 100 times (or more) before performing a full burst test. The result is a comparison of values before and after the cycles and is expressed in percentage loss.

These cycles will subject the fabric to a fatigue effect that simulates handling and use of the fab-ric. It will simulate every time that the fabric is stretched and relaxed, due to folding-unfolding for example, or when a person rolls in bed and stretch-es the net tucked under the mattress. The number of cycles needs to be determined as well as the percentage of pressure to apply, depending on the

application and what is trying to mimic (a whole body leaning on a net is different from an elbow poking into a net).

Tensile cycling treatmentTensile strength is a standard test in textiles, but applies to woven fabrics only. However, a fabric can be fatigued using this instrument. The typical strength test consists of pulling a piece of fabric at a constant rate (speed), and recording the amount of force it takes to stretch it, all the way to break-ing point (see Fig. 7).

Instead of pulling until it breaks, a sample is pulled at a determined percentage (10% of maxi-mum strength for example) for several 100 cycles

FaBrIc FatIGUe can be tested by a universal tensile tester. Instead of pulling the specimen until it breaks, the fabric is pulled with a certain force (e.g. 10% of maximum strength to stretch it to breaking point) for several 100 cycles. In contrast to bursting cyclic treatment, a tensile tester pulls in one direction, which is closer to reality for a mosquito net.

Fig.7

Universal tensile tester

Sp

ecim

en

Gaugelength

Clamp

Fixedjaw

Load cell

Constantrate ofelongation

Clamp



in order to fatigue it. The main difference between tensile and burst cycling treatment is that in a ten-sile tester the pulling direction is unidirectional, which is closer to reality for a mosquito net that is hanging down. Tucking under the mattress always pulls the fabric towards the ground, so the stress is mostly from the top to the bottom of the net.

Stone washing treatmentStone washing is a vigorous washing, intentionally giving a distressed look to a fabric. This process is well known for jeans. The fabric is spun together with rubber/silicon balls or pumice stones in large industrial washing machines. The duration of this process depends on how distressed the fabric should look at the end.

This is a quick and efficient way to age a net in a controlled fashion. Number, size and type of stones and duration of the process will affect the outcome.

Mace snag treatmentAnother way to age a net is to use the mace snag machine – which is used for the ASTM D3939: Snagging resistance of fabrics (Mace) test. A sample of fabric is placed on a rotating cylinder, and a mace randomly “hits” the fabric, bouncing back and forth on the fabric (see Fig. 8).

This test is not recommended for open structures, such as nets. However, what is proposed here is random destruction of the fabric in a “controlled way”, to accelerate wear and tear of the fabric. The number of rotations needs to be determined and then a burst test should be performed.

The mace snag test is recommended when small objects regularly get caught in the net, such as rings, fingernails, hooks or even nails in the wall. Stories of goats biting nets or open umbrellas holding the net in place above the bed or using sticks to hang the net to a hook are not unheard of.

From mild to rough abrasion treatmentThe standard abrasion test uses a standard white wool fabric, but it can be exchanged by any other material, as long as it is in the protocol. It can be rougher or softer, for example, it can be sandpaper

random destrUctIon of the fabric in a “controlled way” accelerates wear and tear. A mace bounces back and forth randomly striking the sample fabric covering the rotating cylinder. A sub-sequent burst test should be performed after a predeter-mined number of rotations. The mace snag test is rec-ommended when small objects regularly get caught in the net.

Fig. 8

article on the enclosed public health cd-rom. here you can also find a box with Who/Jmps specifications for ln (physical tests).

Understanding the real conditions of wear and tear is a key factor for predicting the durability of bednets. There is no protocol describing how to simulate five years of use in the field, but with adequate testing it should be possible to create one. Such a protocol could integrate various tests that are not yet standard for WHO testing, but needs to be discussed openly between industry and the WHO. Designing guidelines for accelerated ageing is a focus for the future and should become an integral part of future LN specifications.

conclUsIon

to mimic sand and dust in a hut. The rubbing will be more strenuous on the net, ageing the net faster.

There are also older machines with a uni- or bi-directional abrasion path. These are also tougher on fabrics. If tucking is always occurring at the same place on the net, and always in the same direction, then these machines would be better suited to replicate real life conditions.

mace snag tester



nder the name LifeNet™ Bayer introduced a brand new net made for the first time from

polypropylene (PP), a polymer from the olefin family. Other available nets are made from polyethylene (PE), a material also from the olefin family. It might be expected that nets made from either polymer would share similar properties. On the other hand, the majority of available nets are made from polyester (PET), a different polymer with different physical behavior.

An example of a PET net is PermaNet™, a polyester multifilament with the active ingredient

coated on the surface of the fiber. An example of a PE net is Olyset™, a monofilament with the active ingredient em bedded in the fiber. The PP LifeNet combines attributes of both: it has the durability of the olefins, the active ingredient embedded in the fiber and the softness of the multifilament yarns such as those from PermaNet.

Several mosquito nets are available on the market to combat malaria in Africa. Made of polyester, polyethylene or polypropylene, these nets all have unique physical properties that make them more or less durable in the field. This article reviews the material strengths and weaknesses of the three different net materials. The results are based on tests carried out in two independent labs.

Different strengths and weaknesses

physical test results on three different mosquito nets

comparison of physical attributes

As a brief overview, a few key properties impacting the use of the materials as a bednet are listed here:

1. Main properties of olefin (LifeNet and Olyset)• Strong fiber.• Resistant to deterioration from chemicals.• Stain and soil resistant. • Abrasion resistant.• Very lightweight (olefin fibers have the lowest

specific gravity of all fibers). • Quick-drying.• Sensitive to heat.• When used as curtains, UV stabilizers to be

added.• Poor resilience when used as monofilament

(ability to recover the original shape and tends to stay wrinkled).

2. Main properties of polyester (PermaNet)• Strong fiber.• Resistant to stretching and shrinking. • Resistant to most chemicals. • Quick-drying. • Crisp and resilient when wet or dry. • Wrinkle and abrasion resistant. • Easy to wash.• Sensitive to heat.

Although both olefins, there are a few differences in the basic properties of polypropylene (LifeNet) and polyethylene (Olyset):

U

The author: severIne hUchet

Consultant on textile testing and quality control, NC State

University, College of Textiles, USA



• Polyethylenecostsmorebecauseitisaproductof higher purity (100% Virgin).

• IngeneralPP is less flexible thanPE, thishasbeen overcome in choosing a multifilament PP net versus the rigid and stiff monofilament PE net.

• MeltingpointofPP(165°C) ishigher thanPE(130°C).

From the general characteristics it can be concluded that all three polymers are excellent candidates for lightweight and convenient mosquito nets, so the differences in suitability are related to the final technology of using the basic materials converted into the final product.

performance tests

In order to assess how one net behaves compared to another, six performance tests mimicking real

life “stress conditions” to the net were carried out by two independent labs: ITV1, a large research institute with testing ability in Germany, and IFTH2, the French textile institute for testing in Lyon. The test procedures are described in more detail in the previous article on page 30.

Burst testA burst test measures the strength of a knitted fabric. It is part of the WHO requirements and all

1 ITV: Institut für Textil- und Verfahrenstechnik Denkendorf2 IFTH: Institut Français du Textile et de l’Habillement

Phot

o: M

iche

lle C

ornu

the BUrstInG strenGth of LifeNet and Olyset was within 2% of each other, reaching about 500 kPa on a 7.3 m2 piece of fabric, while PermaNet withstood only 60% of this value.

Fig. 1

Bursting strength*

500

400

300

200

100

0

492

291

502

PermaNet

LifeNet

Olyset

Bur

stin

g st

reng

th k

Pa/

7.3

cm2

* See page 31

specifications

net

PermaNet

Olyset

LifeNet

Fiber 4

Polyester

Polyethylene

Polypropylene

Filament per yarn

36

1

24

size of yarn (denier)

1175

150

100



netsmustmeetaminimumof250kPaona7.3m2

sample. This test was performed on new nets and is the average of 10 tests (NF EN ISO 19338-1:1999) for LifeNet and Olyset and 5 tests forPermaNet. LifeNet and Olyset proved very com-parable, while PermaNet showed 40% lower strength (see Fig. 1).

Dynamic nail testThis test was performed to evaluate the ability of a fabric to withstand a rip (a rip, or tear is a cut in a fabric) at high speed. This test mimics a sharp object piercing through the net and tearing it down, with some speed, such as a strong pull from a splinter or an animal bite (goats, rodents). A piece of jewelry such as a ring, getting caught in the net and pulling is another example. The French norm NF G 07-147 uses a pendulum system to

create a quick tear once the sample is inserted with a nail. LifeNet proved to be stronger than PermaNet and Olyset, as well as more balanced, with almost equivalent values in both directions (see Fig. 2). Olyset performed poorly in the down direction due to its knit pattern. This test is an excellent predictor of how well nets will handle any quick rip in the field.

Slow nail testThis test was performed to evaluate the ability of a fabric to withstand a slow rip. A slow nail test will mimic a splinter caught in the net, for example. It was performed following DIN 54 301 but wasslightly modified: The sample was 2 cm wide x 10 cm long, the nail was 1 mm and placed in the middle of the sample through one hole. Each test was performed 10 times in each direction. The

colUmn refers to the nail being pulled down, tearing through the rows of fabric. roW means the nail is pulled across the fabric (strength is measured in Newtons).

Fig. 2

dynamic nail test*

50

40

30

20

10

0PermaNet LifeNetOlyset

Str

engt

h (N

)

2419

21

37

51 52

Column Row

* See page 33

the resUlts in black type are the original nets, and the numbers in blue type are the values for washed nets. The overall resistance to slow tearing vertically (Length) or horizontally (Width) is the “Max force”. 1st peak is the force measured just before the first break.

Table 1

slow nail test*

LifeNet

washed

PermaNet

washed

Olyset

washed

33.9

34.9

17.7

15.3

33.9

36.8

26.2

26.2

15.0

11.7

26.2

29.1

35.0

32.6

18.3

17.5

17.9

25.4

24.4

26.2

15.2

12.8

17.9

23.9

Maxforce

N

1stpeak

N

Maxforce

N

1stpeak

N

length Width

* See page 32



results show the maximum overall strength as well as the force measured at the first break in the netting. This experiment was also conducted on multiple-washed nets.

Halfofthenetswerewashedseparately35times,with 10 little bags filled with 100 g of PES granules to create mechanical action. In between washingsthenetsweredried18timesoutof35.Due to a lack of time, the nets were sometime washed twice a day. The nail test was performed in parallel, original vs. washed, for each net (see Table 1).

LifeNet and Olyset were very similar in the length direction but LifeNet was twice as strong as the other nets in the width test. Olyset’s low width result is as mentioned related to its knitting weave

the sInGle loop is a weak point in the knitted chain.

Fig. 3

close-up of olyset net

single loop

chain

a nUmBer oF “compressIon-slacKenInG” cYcles are applied to a circular sample (Ø 145 mm), at a regular speed, using a spherical object. The remaining deformation compared to the starting horizontal level (in mm), or bagging, is recorded.

Fig. 4

Bagging resistance test

60 min

7

Ø 120

Ø 100

Top fixation

Spherical object

SampleRing

Threaded clamp

Lower fixation

(see Fig. 3). Although PermaNet was also very balanced in both directions, LifeNet reached higher values (almost twice as high) in both directions, both before and after washing.

Olyset is shrinking after washing, making more material available to be tested in a 2 cm width band. This was proven by performing a shrinkage test. Olyset had the highest shrinkage values of all three nets. The results would be dramatically different if the samples were “pre-cut” to 2 cm before washing and testing.

Bagging resistance testThis test was performed to evaluate the ability of a fabric to withstand repeated punching over a small area. Bagging is the impression or dent left on the net after repetitive pounding. Nets are subjected to



various stretch forces during use. A person sleeping under a net may roll over and poke the net with an elbow, a shoulder or knee. This movement when repeated over time will deform the net and sagging will appear. It is possible to reproduce this stretch and relaxation effect in the lab using a “bagging test” also known as “punching test” (see Fig. 4).

Under standard recommended conditions (see Table 2) LifeNet showed the least deformation of 1.5mm,whileOlysetsagged8mmafter10cyclesat 100 N. 100 N is equivalent to a 10 kg punch, or

a 2 year-old toddler rolling into the net. When the same test was conducted at a higher impact level (see Table 3) the results showed the same trend. Therefore, LifeNet resisted much better than the other two nets, which sagged two (PermaNet) or three (Olyset) times more under the same conditions.

Abrasion testThe nets were submitted to an abrasion test on a Martindale machine for 15,000 rotations. Theweightusedwas415g.ThestandardDINENISO12947 specifies 9 kPa (which is equivalent toabout 600 g).As long as all three samples weretreated the same way, this deviation from the standard is acceptable.

All three nets performed very well after 15,000rotations, showing no or very little fraying or damaged filaments. Figure 5 shows all three nets sidebysideafter15,000rotations.

From the left: LifeNet, PermaNet, and Olyset netting material after 15,000 rotations in the abrasion test.

Fig. 5

nets after abrasion test

Data from high impact tests.

Table 3

Bagging test results

net

PermaNet

Olyset

LifeNet

Bagging(mm)

4

8

1.5

net

PermaNet

Olyset

LifeNet

Bagging(mm)

11

14

5

Extent of deformation under standard conditions

Strip tensile testITV performed a tensile test according to DIN EN ISO 13934 T1, which is a strip test. Although tensile tests are not recommended for knitted fabrics, it can sometimes give useful information about behavior in the field. Not all stress on knitted fabrics are 3D (like a bursting strength test), but often the stress is unidirectional.

the BaGGInG test condItIons according to standard (Norm) and high impact conditions. High-impact bagging applied 250 N of pressure for 100 cycles compared to the recommended norm of 100 N for 10 cycles.

Table 2

Bagging test conditions

norm nF

G 07 213 high impact

Cycles (number of punches) 10 100

Force applied 100 N 250 N

Speed 100 mm/min 100 mm/min



article on the enclosed public health cd-rom.

It was found that LifeNet, Bayer’s new polypropylene net, performed very similarly to Olyset under physical loads and stress, and muchbetterthanPermaNet.Moreover,LifeNetproved to be more balanced than Olyset, with equivalent results in both directions for a number of different tests (slow and dynamic nail tests and tensile strip test). In addition, LifeNet showed an overall lower variance in tests, compared to Olyset and PermaNet, indicating good consistency, quality and reproducibility throughout the net when tested. A key finding was that LifeNet performed extremely well on the dynamic nail test, a predictor for holes due to splinters, from a bed frame for example. Therefore, from a physical durability point of view, it is expected that the new polypropylene LifeNet will behave even better than the current seen standard for a strong net – Olyset, its olefin cousin, while keeping the softness of multifilament nets like PermaNet.

conclUsIon

Before washing, LifeNet was four times stronger in the width direction than Olyset, and still twice as strong after washing (see Table 4). LifeNet was the best compromise in terms of strength and balance in both directions, while Olyset remained unbalanced in the length versus width resistance to tensile forces (see Fig. 3). With a much lower strength in the width direction, Olyset is most likely to fail (tearing, breaking) after a “strong pull” sideways. Olyset is strong in the length direction (which is how the net is used when tucked under a mattress), but if people pull it sideways to close a gap, or grab the edge of the net and pull it horizontally, or if it gets stuck (with a

splinter, or the weight of a mattress), then it will breakeasily(itonlytakes2kgona2.5cmbandto break the fabric). A burst test will not show this type of weakness. Although a tensile test is not appropriate for knittware, this confirms a weakness in the width direction of Olyset (see Fig. 3). Olyset is stronger after being washed, proving that it shrinks more than the others, and more material is pulled together (see slow nail test, Table 1). The same comment applies for the length direction where Olyset “gained” strength when it is only shrinking more.

each sample was 25 mm wide, and the test was performed five times in each direction (length, width). The results recorded are the maximum tensile strength (force, N) and relative stretch (extension) of the material compared to the starting size (%).The numbers in black type are the original nets, and those in blue type are the values for washed nets. Washing conditions were the same as described in the slow nail test (Table 1).

Table 4

tensile test results

LifeNet

washed

PermaNet

washed

Olyset

washed

160.6

128.6

95.3

75.8

169.9

175.8

78.9

76.1

51.7

91.1

98.8

118.2

92.4

98.8

63.0

86.8

23.3

42.5

132.1

103.1

81.0

88.3

278.2

294.7

ForceN

Extension%

ForceN

Extension%

length Widthoriginal



ffective insecticide-based control of any disease vector ideally requires the deployment

of the insecticide as a persistent residue in locations where the vector will arrive at some point in its life. This must be done without any risk to humans or animals and without damaging the environment. It must also be delivered via a method that is understood and adopted by the communities being targeted to receive protection.

The adults of many of the most important mosquito vectors of human disease rest or blood-feed in the man-made peridomestic environ-ment. Thus simple interventions like indoor residual spraying (IRS) and insecticide-treated bednets (ITNs) have been very successful in targeting vectors of malaria and other infections worldwide. Strategies like these that control the adult stages also have an advantage over control of the immature stages because they can shorten adult lifespan, which potentially reduces pathogen transmission, since fewer mosquitoes live long enough to become infective. Controlling the developing stages, on the other hand, will only reduce vector density.

Dengue continues to spread rapidly worldwide and prevention relies on vector control. Despite the apparent simplicity of its life cycle, Aedes aegypti has proven to be a remarkably difficult vector to control effectively. Today, although experts in the field agree that community-based methods are most likely to provide sustainable control, a suitable effective intervention tool remains elusive. Could insecticide-treated curtains be the solution?

An effective method for dengue control?

Insecticide-treated curtains (Itcs)

Itns not suitable for day-biting mosquitoes

ITNs have a particular advantage in that they can be packaged and distributed relatively easily and do not require the technological equipment or skills

base needed for IRS. Indeed, they have yet to reach their full potential in prevention of vector-borne disease in Africa and elsewhere. However, they are not suitable for every type of disease vector or every situation where mosquitoes and other vectors transmit human disease. For example, many diseases are transmitted by day-biting mosquitoes (i.e. when people are not asleep inside the bednet), or by species that rest or bite outdoors. One of the most important species fitting this description is Aedes aegypti, the primary vector of dengue worldwide*.

Dengue is the most important (in numerical terms) and fastest-spreading arthropod-borne viral disease of public health significance. Only nine countries had dengue in the 1950s, compared with more than 100 countries worldwide today. The WHO estimates that more than 2.5 billion people

E

* Yellow fever also is transmitted by Aedes aegypti to humans in urban cycles in Africa and South America. Unlike dengue however, a highly effective vaccine is available and is the pri-mary method for control of outbreaks.

The author: phIlIp mccall

Vector biologist, Liverpool School of

Tropical Medicine, UK



InsectIcIde-ImpreGnated cUrtaIns serve their purpose anywhere within or around the household – like here in a corridor entry in peru.

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are at risk.1 Moreover, the more severe and sometimes fatal forms of dengue known as dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS) are on the increase. There is no vaccine.

dengue vector difficult to control

The primary dengue vector, Ae. aegypti is a cos-motropical mosquito species that typically com-pletes its entire life cycle within the domestic environment. Adult mosquitoes do not fly far, rarely dispersing more than 100 meters beyond the emergence location. They are highly anthropo-philic and are found only in association with humans. Ae. aegypti breeds in many types of household containers, such as water storage jars, drums, tanks and plant or flower containers, and rests between blood-meals within and around the house.

Despite the apparent simplicity of the life cycle, control of this vector has proven to be very diffi-cult. Many eradication attempts failed, for various reasons: vertical programs were inefficient and unsustainable, outdoor space spraying was inef-fective; often, insecticide treatments were rejected by communities, or educational messages to the population were unsuccessful.2 Moreover, existing dengue prevention strategies targeted only the aquatic stages of the vector, rather than adult mos-quitoes. What was needed was an intervention with all the advantages and efficacy of an ITN. An early trial with standard ITNs was carried out in the relatively small houses in Leogane in Haiti. Results showed some initial impact but little evi-dence for a sustained effect on Ae. aegypti populations.3 Not unexpectedly perhaps, ITNs would not have reached more than a portion of the

Source: World Health Organization

countries/areas at risk of dengue transmission, 2008

January isotherm 10 °C

July isotherm 10 °C

Countries or areas at risk are marked in red.

The dotted lines of the January and July isotherms indicate the potential geographical limits of the northern and southern hemispheres for year-round survival of Aedes aegypti, the principal mosquito vector of dengue viruses.



diurnally active Ae. aegypti population, even though householders in the Haiti study were encouraged to let their bednets hang down in place during the day to increase the amount of insecticide-treated surface exposed. This is unlike standard practice for malaria control, where owners are encouraged to tie them back in the daytime to avoid damage. Insecticidal barrier around the house

A method more suitable for Ae. aegypti was needed, and insecticide-treated curtains (ITCs) began to receive attention. In the context of this article, curtains are defined as sheets or strips of netting or fabric suspended anywhere within or around the household, e.g. window curtains or doorway screens, room dividers, cupboard, ward-robe or storage recess curtains, etc. Typically, these curtains would serve purposes other than simply mosquito control, and thus it was hoped that their role in providing privacy, as sun screens on windows, their decorative properties, etc., would increase their acceptability and the chance of their widespread and correct usage.

Insecticide-treated net curtains hung in eaves, doors, and windows had been used previously against anophelines in Africa and successfully reduced malaria transmission, particularly in loca-tions such as Burkina Faso4, where the high night time indoor temperatures made sleeping within an ITN very uncomfortable. In those cases, with the inhabitants asleep and immobile inside the house, such curtains would have formed an almost com-plete insecticidal barrier around the house, one that would rarely be disturbed during the targeted vectors’ biting times.

Itcs reduce vector populations

Interest in ITCs for dengue vector control is rela-tively recent, and the first studies were undertaken only within the past eight years. To my knowl-edge, all studies have used long-lasting netting material, identical to that used in the manufacture of long-lasting insecticidal nets (LNs) for malaria prevention. To date, results of only two studies

have been published. Both of these cluster-ran-domized trials in Mexico and Venezuela demon-strated that ITCs reduced dengue vector densities to low levels.5 In Mexico, ITCs were tested alone, while in Venezuela the treated houses received both ITCs and insecticide-treated water container covers.

In both studies, ITCs were well accepted by the communities and reduced vector populations in both treated households and households in nearby untreated control clusters. This “spill-over effect” was such that houses without ITMs located close to treated houses were less likely to have infesta-tions than those further away. Presumably, the risk of a host-seeking mosquito contacting an ITC was high, and most died younger and laid fewer eggs. If so, life expectancy was reduced and the age structure of the vector population was altered, with few mosquitoes likely to live long enough to become infective with dengue. Certainly, although far from conclusive, there was some support for this in the Venezuela study, where dengue trans-mission, as measured by IgM seroconversion rates in humans, did appear to be reduced during the trial.

Since then four further larger trials in Venezuela and Thailand have been completed and publication of their results is expected very soon. Additional trials are underway in Peru, Guatemala, Brazil, Mexico, Thailand, and Vietnam, as well as other countries, and WHO has recommended that ITCs are tested in additional trials in many more locations and contexts.1

different demands on the materials

Precisely how ITCs might work is a matter of speculation, given how little is known about Ae. aegypti behavior within households, not to men-

aedes aeGYptIare highly anthropophilic and only found in associa-tion with humans.



tion how few ITC studies have been completed. Ae. aegypti must enter or leave houses via open-ings such as windows, doors, or through eaves or open roofs and similar spaces. Presumably, plac-ing ITM barriers in these routes will target at least a proportion of the population, as they fly “blind-ly” into contact with the treated surfaces while entering, or exiting, to pursue hosts or seek resting or oviposition sites. This assumes that the pres-ence of insecticide on the curtains is not detected in-flight by the mosquito. If this is the case, then it

throughout the house. This is likely to require a change in human behavior, always a real challenge to ITC efficacy. ITCs hung in windows will be exposed to strong sunlight and therefore more likely to lose insecticidal efficacy more rapidly than bednets or indoor curtains. Similarly, given that many ITCs will be in doorways or corridors, wear and tear on the fabric and the build up of dust and grease from human hands will limit the effec-tive lifespan of a curtain. These potential problems will be both a technical challenge to the manufac-turers and a marketing or promotional challenge to those encouraging their use. Potentially, re-treat-ing curtains with insecticide may eventually have to be considered a reality, although this is rarely advocated today, in the era of LNs.

Itcs in schools or workplaces

Differences in routine human activities between different societies will play a very important part in ensuring that ITCs exert a protective effect. For example, in some societies, adults and children are already on their way to work and school, or perhaps already there, by the time dengue vector biting reaches its morning peak. If so, then deployment of ITCs in schools or workplaces may also need to be considered. Later in the day, after school, children may play outdoors when the afternoon/evening peak in biting occurs, particularly in certain seasons.

Intact insecticide-treated bednets, when correctly used, provide a complete highly effective barrier around the sleeping human against nocturnally active indoor feeding vectors. Given that humans are at their most active when Ae. aegypti are also actively host-seeking, providing similarly com-plete protection is quite an expectation. Thus, it may be unreasonable to expect that ITCs will ever be able to deliver such complete protection against dengue transmission, even when used correctly by the majority of households. Some level of Ae. aegypti biting also occurs outdoors. However, these words of caution are merely speculative and consideration of the magnitude of these potential drawbacks must wait until the results of further trials are available.

WIndoW cUrtaIns in a schoolroom (Thailand) help protect adults and children.

might also be assumed that ITCs are likely to have greater impact in more “closed” houses, where there are fewer or smaller doors, windows and eaves than in houses that are more open to the exterior, since the relative proportion of unprotected space through which mosquitoes might pass will be less in the “closed” houses.

It also means that to control dengue vectors, ITCs will need to be left in place during the day. This might be a problem because at these times people are active about the house and curtains in windows and doors are more likely to be tied back to let in fresh air and light, and permit ease of movement

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Itcs combined with Itns

Although this article has dealt with ITCs in rela-tion to dengue control, they may also have great potential for control or prevention of other vector-borne diseases, including malaria, as already shown in Africa4. It has been reported from den-gue trials that ITC efficacy was reinforced by the sight each morning of dead insects (cockroaches, houseflies and other pests, as well as mosquitoes) beneath the treated curtains5. This is not surprising since insecticide residues placed within the home will inevitably contact and kill at least some of those insects moving around inside. However, whether a large enough proportion of the pests of interest are killed to reduce biting, let alone trans-mission, remains to be determined for each vector.

It is highly likely that any intervention that reduces nocturnal biting by Culex quinquefasciatus would be perceived as beneficial, anywhere in the world. ITNs have been shown to impact on vectors of malaria, lymphatic filariasis, leishmaniasis and Chagas disease, and in many locations worldwide, ITCs might be expected to be effective too. Unlike dengue however, most of these diseases are transmitted by nocturnally active vectors, but it may prove easier to persuade communities to hang their ITCs in place at night, when they not only provide a degree of privacy, but also when people often perceive mosquitoes to be a problem and when they already use ITNs for that reason.

potential for varying design and insecticide

Finally, two important issues remain that might limit the potential of household-based interven-tions like ITCs, regardless of how effective they are in principle. The first is willingness of com-munities to accept and regularly use the interven-tion. Clearly, the more households in an affected area that use ITCs, the more likely they are to suc-ceed. The experience with ITNs has indicated that it is often human behavior that limits the potential of the tool rather than the technical or entomo-logical challenges. ITCs have an advantage over ITNs because they offer greater variation in the

article (with references) on the enclosed public health cd-rom

There is no reason to expect ITCs to do the entire job of dengue vector control alone. The majority of countries affected by dengue already have a range of measures in place, largely aimed at reducing vector populations via clean-up campaigns and control of Ae. aegypti larvae and pupae with insecticides. Combining ITCs with existing strategies may prove to be the best route to reducing not only dengue transmission, but also vectors of malaria, lymphatic filariasis, leishmaniasis and Chagas disease in many locations worldwide.

conclUsIon

range of designs/patterns, colors and materials that can be used, and in the number of locations where they might be placed; the former might be exploited to increase their desirability, the latter circumvents the discomfort and effort of a bednet, possibly increasing acceptability and usage.

The final and crucial issue that will determine the future of ITCs in vector control is the fact that today, as with bednets, insecticide-treatment of net-ting remains restricted to pyrethroids. With pyre-throid resistance increasing worldwide in many vectors including Ae. aegypti, the need to broaden the range of insecticide families that can be loaded onto netting must be addressed. ITCs could provide a solution here, since unlike insecticide-treated bed-nets, which remain close to the sleeping human for many hours, in contact with the skin and close to the face, ITCs hung in windows or cupboards or even in doorways are contacted far less frequently and might therefore be acceptable vehicles for delivery of insecticides other than pyrethroids.

Before we rush into such developments however, we must await the results of the many trials cur-rently underway to determine whether ITCs can reduce dengue vector populations, and if such reductions result in lower rates of dengue trans-mission.

p r o f i l e


LNs, along with timely diagnosis and treatment with life-saving drugs, are an essential compo-nent of the malaria control tool-box, and part of an integrated strategy to achieving elimination as outlined in RBM’s Global Malaria Action Plan. AMP part-ners are working towards cover-ing every person at risk of malaria with preventive technol-ogy and, in the process, contributing to attaining the Millennium Development Goals (MDGs) by 2015.

The UN Secretary General Ban Ki-moon’s challenge for univer-sal mosquito net coverage of

populations at risk of malaria goes beyond the end of 2010 and requires further mass mobiliza-tion of donors, governments, partners and the private and public sectors. Supplies of long-lasting insecticidal nets (LNs) must be scaled-up to meet coun-try needs, while implementation capacity must be strengthened at country level to ensure that LNs are successfully delivered to targeted populations. Mass dis-tribution of LNs involves com-plex logistics at every stage, from manufacture to delivery, storage, distribution and follow up to ensure use. These cam-paigns have been successful in rapidly increasing coverage of

populations at risk of malaria in Africa, Asia and the Americas.

A subgroup of the Roll Back Malaria Partnership (RBM) and the Harmonization Working Group, the Alliance for Malaria Prevention is a partnership involving over 40 members. These include government agen-cies, private sector businesses, public sector organizations, humanitarian organizations, LN manufacturers and others (see box on page 49). All these partners provide invaluable support towards reaching the RBM targets and the Millennium

Alliance for Malaria prevention (AMp)

Protection for everybodyThe Alliance for Malaria Prevention (AMP) represents more than 40 partners, including government, business, faith-based and humanitarian organizations. Its goal is to expand the ownership and use of LNs, which have been shown to reduce malaria incidence by 50 percent and reduce all-cause child mortality by 20 percent.

eVerYBoDY AT riSK of catching malaria should be able to sleep under a mosquito net.

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- The Academy for Educational Development (AED)- Africa’s Health in 2010- Against Malaria- American Red Cross- BASF- Bayer- British Government’s Department for International Development (DfID)- Canadian Red Cross (CRC)- Canadian International Development Agency (CIDA)- European Alliance Against Malaria (EAAM)- Exxon Mobil Corporation- The Global Fund to Fight AIDS, Tuberculosis, and Malaria- Global Health Advocates- International Federation of Red Cross and Red Crescent Societies (IFRC)- Immunization Basics- Izumi Foundation- Johns Hopkins University Center for Communication Programs- HIS Nets- Lutheran World Relief- MACEPA- Medical Care Development International (MCDI)- Malaria Consortium- Malaria No More- The MENTOR Initiative- Net Project- Nets for Life- Nothing but Nets- Population Services International (PSI)- The President’s Malaria Initiative (PMI)- Rotarians Against Malaria- Sumitomo Chemical- Syngenta- Tana Netting- United Nations Children’s Fund (UNICEF)- United Nations Foundation- U.S. Centers for Disease Control and Prevention- The United Methodist Church- United States Agency for International Development (USAID)- The World Bank- The World Health Organization- World Vision- Additional LN manufacturers

partners of the Alliance for Malaria preventionDevelopment Goals of reducing child mortality by two thirds by 2015.

Health package including lns

The Alliance for Malaria Prevention partnership began as the Measles-Malaria partnership in 2002 when LNs were first integrated in a mass vaccination campaign in one district in northern Ghana. The campaign targeted children under five years of age and included vacci-nation against measles, vitamin A supplementation and distribu-tion of LNs in a pilot project to assess the feasibility of using the vaccination platform to rapidly scale-up coverage of one of the most vulnerable population groups.

The integrated campaign model proved to be a cost-effective strategy for delivering nets to children, and was scaled-up in 2003 to five districts in Zambia and in 2004 to children under five years of age throughout Togo. The success of these dis-tributions, and the evidence-base created through post-distribution evaluations, persuaded interna-tional donor organizations and

THiS ToolKiT has been developed by the Alliance for Malaria Prevention to help people plan successful mosquito net campaigns at all stages, from interna-tional cooperation to local distribution.


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implementing partners to sup-port integrating net distribution into such child health cam-paigns. Support for mass distri-bution of LNs has continued with the policy shift to universal coverage, though most of these distributions are not integrated with other interventions.

Since 2002, African Ministries of Health and National Malaria Control Programs (NMCPs) have distributed millions of LNs to reduce the incidence of malaria. This has often involved local and international partners and the Alliance for Malaria Prevention working together to support NMCP staff with deliv-ery of LNs to persons or groups at risk of malaria. Integrated campaigns have been successful for covering children under five as a specific target group for improved child survival (includ-ing measles or polio vaccination, vitamin A supplements, or treat-ment for intestinal worms), while stand alone campaigns have been more effective where the entire population at risk of malaria is targeted. Mass cam-paign delivery is primarily for rapidly increasing coverage and use of LNs, and campaigns are complemented by routine deliv-ery of LNs to pregnant women during antenatal care visits and/or to children under five during routine immunization and child health visits at health centers.

Working groups

AMP partners are invited to par-ticipate in any of the partner-

ship’s working groups. These working groups include:

• Behavior change communication (BCC)• Monitoring and Evaluation (M&E)• Operational Research (OR)• Toolkit• Training• Emerging Issues• Sustaining Gains

Communication is a vital activity at all stages and levels, from coordinating international part-ners to encouraging individuals and families to use LNs. Behavior change communica-tion is important to promote sus-tained use and maintenance (care and repair) of bednets.

proper planning

AMP developed a toolkit in 2008 to help with planning, budgeting, logistics, communi-cation and monitoring, and eval-uation of mass LN distribution based on experiences and lessons learned since 2002. This infor-mation was compiled with the help of documents provided by the Ministries of Health in Angola, Chad, Cote d’Ivoire, Liberia, Madagascar, Mali, Níger, Nigeria, Rwanda, Sierra

Leone, Togo, and Zambia. The 2008 toolkit, “A toolkit for developing integrated campaigns to encourage the distribution and use of long lasting insecticide-treat nets”, was revised in 2010 to take into account the shift to universal coverage, and lessons learned by countries who have planned and implemented cam-paigns targeting the entire at-risk population for malaria.

Proper planning is essential since the shipping and delivery of mass quantities of bednets represents unprecedented logis-tics, coordination and organiza-tion challenges. The Alliance for Malaria Prevention provides technical assistance and support to countries through a number of channels: email or phone confer-ences for country-specific issues; in-country support missions on request of NMCP or implement-ing partner organizations. And training organized in 2009 and 2010 focused on specific aspects of LN scale-up (overall cam-paign planning and implementa-tion, logistics, monitoring and evaluation, behaviour change communication). Once a week, partners involved with the Alliance for Malaria Prevention meet on a conference call to

HigH CoVerAge of insecticide-treated nets help greatly reduce mortality in many African countries.

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The objectives are clear and the funding is available. Current challenges to LN scale-up include, or remain, coordinating partners, defin-ing distribution strategies, ensuring supply chain man-agement and logistics, and communication to reduce the gap between ownership and utilization of LNs distributed. Building on the experience gained during planning and implementation of integrated vaccination and nutritional campaigns targeting children under five, AMP’s goal is to help reach universal cover-age to reduce the risk of malaria, and contribute to reaching the MDGs by 2015. This means delivery of mil-lions of nets over the coming years to cover all persons at risk of malaria with a long-lasting insecticidal net.

ConCluSion

Article on the enclosed public Health CD-roM

More

www.allianceformalariaprevention.com/www.malarianomore.org/www.buyanet.ca/www.redcross-eu.net/www.macepalearningcommunity.org

review progress and challenges with countries planning or implementing mass LN distribu-tions. The weekly meeting allows for discussion around les-sons learned and optimal approaches to delivery and distribution of LNs with partici-pants from many different coun-tries and organizations.

It is clear that successful imple-mentation of mass distribution campaigns needs detailed macro and micro planning for transpor-tation, storage, monitoring and stock control of LNs. Countries may opt for centralized (e.g. warehoused at port or point of entry to the country, or in regional hubs) or decentralized (LN delivery in containers to regional or district storage points without being warehoused else-where) logistics depending on infrastructure of the country and security outside the central level. Regardless of whether the logis-tics operation is centralized or decentralized, control over the supply chain with appropriate tracking and monitoring tools, as well as ensuring security during transportation and storage, are crucial.

At distribution sites, a number of concerns must be addressed, including adequate personnel for crowd control and delivery of LNs, and safe waste disposal of plastic packaging. As more LNs have been distributed in coun-tries, replacement of existing, non-viable nets has become an issue, which is currently being addressed through pilot research

led by WHO in three African countries.

Planning for distinguished visi-tors is also important. With the new era of philanthropy (see PHJ No. 19), entrepreneurs, politicians and celebrities often want to visit countries to see campaign implementation, nota-bly to view how contributed resources are being used to improve the lives of beneficia-ries. Their advocacy around LN scale-up and further support for the activity is encouraged by suitable strategies to make their visit run smoothly, with tips on how to do this described in the AMP toolkit.

Scaling-up

In 2010, to support the AMP working group, the International Federation of the Red Cross (IFRC) led an initiative hosted by the Red Cross/EU Office. This was to promote a one-year project called “Scaling-up European Commitment to reach malaria 2010 universal coverage and MDGs objectives” as a con-tinuation of the European Alliance Against Malaria.

High coverage rates of insecti-cide-treated nets (ITNs) com-bined with early diagnosis and treatment have been shown to

greatly reduce mortality in many African countries. So far the only effective method of achiev-ing rapid, high and equitable coverage is mass campaigns that distribute LNs free of charge to beneficiaries. Donors from many sectors are now contributing millions of dollars to support such mass campaigns.


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It might not be common knowledge, but Bayer has the longest unbroken company history in the supply of high quality chemical solutions for vector control as a main part of integrated disease management (IDM).

Having gone through an evolution from a pure product supplier to a solutions provider, Bayer saw the need for greater focus on the judicious use of its products, seeing the overall context in which the products are used in terms of product stewardship and corporate social responsibility.

One issue that impacts the use of pesticides is increasing insecticide resistance, which endangers disease control, e.g. in malaria, dengue and Chagas disease. As more vector control programs are conducted (which is good), the more these vectors are under selection pressure for resistance (which is bad). So it should be imperative for each R&D driven pesticide company to continue to develop and implement effective insecticide resistance management (IRM) strategies.

Bayer is in a unique position with its multi-active ingredient portfolio to implement IRM programs, e.g. with the rotational use of different active agents in adult vector control. In IRS programs in malaria and Chagas disease control, the rotational use of a carbamate (bendiocarb, Ficam®) with a recommended pyrethroid is now standard practice.

Besides having the right chemical tools, Bayer took the responsibility to communicate and educate stakeholders about the strategies and the need for IRM. Bayer conducted a series of international and national workshops in Africa and Asia from 2004 until now, as well as providing published technical materials, and working actively in expert groups such as IRAC (Insecticide

Resistance matters: New publication on IRM

Resistance Action Committee). The growing importance of insecticide resistance in the context of vector-borne disease is something Bayer is therefore well placed to manage and provide assistance.

The most recent tool is Bayer’s new “Resistance Matters” publication, which is a further expression of its commitment to contributing to finding

solutions for this burning issue.

The publication explains not only the scientific background, such as what is resistance, the resistance types, mechanisms, selection process, and so on, but also identifies methods to help reduce the significance of resistance by adopting clear IRM strategies, e.g. when and which type. The role of

Bayer as a pioneer in providing actual solutions for operational IRM is highlighted with case studies. Bayer is committed to helping shape the future and find new modes of action, e.g. with its cooperation with the Innovative Vector Control Consortium (IVCC) and through its own development pipeline.

With this new publication, Bayer wants to start a process of discussions to bring IRM into a broader picture, and into the minds of program implementers, donors, and other decision makers. For Bayer it is a clear goal to make IRM, and resistance monitoring and evaluation an integral part of its program toolkit. IRM is an essential part of integrated vector management (IVM), which is an essential part of integrated disease management.

Publication “Resistance matters” on the enclosed Public Health CD-RoM


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A recent mortality survey estimated that the number of people dying from malaria in India is between 125,000 and 277,000 per year. This analysis published in the Lancet (Vol. 376, Issue 9754, pp. 1768-1774, 2010) by an international research team in October 2010 greatly exceeds the WHO estimate of 15,000 annual deaths.

Generally, malaria mortality is difficult to assess since when reliably diagnosed, usually in a clinical setting, the disease is easily cured if treated early enough. However, where healthcare is limited, deaths from malaria are easily mistaken for other causes, and there is usually no proper medical attention at the time of death.

“India is the most populous country in which malaria is common. The cases and deaths reported by the Indian Government are concentrated mainly in a few states … (and) the Indian National Malaria Program cures nearly all cases it treats”, report the scientists conducting the survey. They therefore wanted to investigate death rates throughout India, so chose random regions to study 122,000 causes

India: Malaria deaths underestimated

of death. In 3.6% of all cases, death could be attributed to malaria, with 90% of these mortalities occurring in rural areas, and 86% of patients seeing no qualified healthcare workers. Malaria mortality also correlated with geographical P. falciparum transmission rates determined independently by the Indian malaria control program.

Extrapolating these results to the whole of India, the researchers estimate that about 55,000 infants, 30,000 children aged 5–14, and 120,000 people from 15 up to the age of 70 die every year from malaria. Thus malaria probably accounts for a significant number of the 1.3 million unattended deaths currently explained as an undiagnosed fever in rural India.

Moreover, in the Lancet article the authors suggest “that the low WHO estimate of malaria deaths in India (and only 100,000 adult malaria deaths worldwide) should be reconsidered.” This proposal could indeed open new perspectives. More accurate estimates of malaria mortality should provide better rational reasons for funding preventative malaria measures, providing more rapid access to malaria diagnosis and supplying affordable effective antimalarial drugs to children and adults in India, Africa and other regions with high malaria burdens.

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Strong and effectiveLifenet

Specific criteria were set when developing LifeNet: Bayer wanted no less than to develop the physically strongest and most effective mosquito net. This was achieved with netting based on a new strong material, polypropylene, which is the first time this has been used in a health textile. Polypropylene is already known as a durable and strong material from the automobile industry, in furniture, and as packing material, etc.

Production of LifeNet is based on a new inclusion technology that retains and releases the active agent to the outside only when needed. This revolutionary slow release technology is the basis for the outstanding wash resistance and the expected long durability in the field. Also the insecticide used as the active agent to treat LifeNet LNs is the strongest pyrethroid (deltamethrin).

Other important con sid-erations were to develop a user-friendly net. This is an important factor because in practical daily use, acceptance by the user plays a vital role. The material is soft to the touch, has nice free-fall characteristics, and the weave is multifilament. All this makes it resilient to wear and tear, easy to use, and pleasant to have in the home. Moreover, LifeNet is effective against Culex as well as Anopheles mosquito species. This is also a protective measure against other mosquito-

borne diseases (e.g. West Nile virus, filariasis) in addition to malaria.

LifeNet supersedes the current WHO criteria for LNs and sets new standards. The insecticide-treated netting lasts much longer than the requested washing intervals, while retaining the required efficacy.

All in all, Bayer has developed a net that includes all the features that should make the nets well liked by people who use them. It is physically stronger than other nets that are currently available, and it is more cost-

effective. LifeNet LNs last longer in the field, thereby reducing the need for “all in – all out” distribution cycles. This reduces needed re -plenish ment between cycles, leading to reduced program costs over time.

High efficacy, and long life lead to reduced health impact costs, e.g. DALY’s averted, malaria cases averted, etc. (see previous article). This is especially important for difficult to access regions where distribution is problematic. Finally,

multifilament PP-based LifeNet is fully comparable to PET nets in terms of logistics, such as number of nets per container. This results in a clear cost advantage compared to bulky PE nets.

LifeNet has passed WHOPES Phase I and is currently in Phase II trials. Results are expected by mid 2011.

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he huge numbers of people succumbing to malaria and

other vector-borne diseases during World War II and its aftermath (see book review, page 56) highlighted the urgent need to control these diseases. Even before the WHO was created, the interim commission appointed an expert committee on malaria, who recommended establishing a subcommittee on insecticides.

Once established, WHO clearly perceived the need not only to use pesticides to control vector-borne diseases, but also to ensure their quality and safety. In addition, it sought to understand the health implications of pesticide use and provide guidance to member states. As resistance among vectors and pests became apparent, new products were developed, and WHO took on an increasingly prominent role in evaluating and testing new pesticides.

In 1960, WHO created its “Programme for the Evaluation and Testing of New Insecticides” with the approval of the World

Established in 1960, last year the WHO Pesticide Evaluation Scheme celebrated 50 years of supporting national programs and other stakeholders in the selection and safe use of public health pesticides. Publishing the history of WHOPES provided an opportunity to analyze how it has adapted to changing demands in campaigns to control vector-borne diseases.

Setting standards for safe use

T

50 years of the WHo Pesticide evaluation scheme (WHoPes)

Health Assembly, and in response to requests from dis-ease control programs, member states and the director general. From the start the scheme worked in collaboration with the chemical industry, research and government institutions, and regulatory agencies. It was renamed the “WHO Pesticide Evaluation Scheme (WHOPES)” in November 1982.

In recent years, renewed efforts to control malaria and other vector-borne diseases have significantly increased pesticide

use for vector control and personal protection. This has further increased the role and responsibilities of WHOPES. The recommendations and quality standards set by WHOPES are invaluable for accelerating the evaluation, registration and use of pesticide products in disease endemic countries.

In commemoration of 50 years of its pesticide evaluation scheme, WHO published a history of WHOPES covering all the different phases of its development and growth to present day reorganization and renewed expansion. Not only does the brochure provide his-torical perspectives of pesticide development and use, but also detailed descriptions of tests, trials and strategies applied to combating malaria and other vector-borne diseases over the last half century.

Brochure “50 years WHo Pesticide evaluation scheme” on the enclosed Public Health CD-RoM

More

http://www.who.int/whopes/en/http://whqlibdoc.who.int/publications/2010/9789241599276_eng.pdf


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he mysteries are many. How does the malaria para-

site actually cause death, particularly in children? Why after exposure do people never develop protective life-long or even long-term immunity? How do the parasite and its mosquito vector manage to develop resis-tance so rapidly to every agent we develop? How and why, despite knowing how to control malaria for over a century, we have still failed to curb this devastating disease that kills close to a million people each year?

Like the very best detective story, Sonia Shah leads us through the complex maze of malaria: from the life cycle of the parasite, and intricate tricks of how it spreads and adapts, to the historical events, genetic changes and millennia of suffer-ing this disease has imposed on mankind. It has driven the rise and fall of ethnic groups, colo-nies, nations, empires, and armies.

In The Fever Sonia Shah traces the long history of malaria up to the present time. Not only is the book packed with information, but its lucid style makes it a compelling story with important messages relevant today.

Malaria, the persistent enemy

T “Roman fever” as malaria was often called in Europe probably protected ancient Rome from invasion for many years, but ultimately led to the collapse of the Roman Empire. In the First World War on the Macedonian front, and World War II in the Pacific malaria laid claim to far more casualties than enemy combat.

Above all, malaria leads to poverty, and poverty leads to malaria. No coincidence then that malaria finally receded from Europe and North America with improved agricultural practices and advancing industrial tech-nologies. Better housing, sanita-tion, public welfare and health all linked to more prosperity, and retreating malaria. Nor should we forget that this happened not so long ago, with no guarantee that malaria won't return to the industrialized West in tow with climate change.

Shah's masterfully crafted, exhaustively researched and lucidly written account leaves no

stone unturned, and provides fascinating, if not disturbing insights for everybody, from non-experts to the most experi-enced malariologist. Particularly, the problem of rapid resistance to insecticides and antimalarial drugs stresses other important historical lessons we must not forget – and highlights how we must avoid this happening today.

Shah warns that our most power-ful medical weapon (artemisinin combination therapies) is being compromised by non-regulated sales of sub-standard artemisinin alone, meaning resistance is now emerging to this drug.

However, we have learned some things from history. The antimalarial drug artemisinin was discovered by studying ancient Chinese texts on medical

sonIA sHAH is an investigative journalist

who has written for New Scientist, The Washington Post, The Boston

Globe and elsewhere. She is also an acclaimed author

of several books.

Book Review

n o t e s

“The Fever: How malaria has ruled humankind for 500,000 years” by Sonia ShahPublished by: Sarah Crichton BooksPrice: US$ 26

remedies, and our most powerful preventative weapon, the mos-quito bednet, was described in ancient times. Nowadays bed-nets are treated with insecticides that retain their efficacy for up to five years and 40 washes. When used correctly they greatly reduce infant mortality. But Shah argues that just delivering bednets is not enough. In coun-tries where malaria is considered no more serious than the com-mon cold, building awareness and antimalarial infrastructures are essential.

The moral of the story is: Never underestimate the enemy! As Shah reminds us, quick-fix, short-term, single solutions, with top-down political, scien-tific and economic agendas don't work. Combating malaria needs concerted, multiple, sustainable campaigns tailored and orga-nized to suit each and every local situation. Above all, every sector, politicians, donors, research institutes, lobby groups and the pharmaceutical industry, must commit to very long-term cooperation. Sitting back to celebrate perceived victory will just allow the enemy to rebound with renewed vigor.

The malaria parasite has evolved in at least nine species of African primates (chimpanzees, gorillas, bonobos) that are genetically very close to humans. For thousands of years malaria has also plagued humankind (see book review, left). But the question was where did the prevalent and lethal malaria parasite responsible for human disease and deaths, Plasmodium falciparum, originally come from?

Previously, it was believed that the closest relative of P. falciparum was P. reichenowi, a parasite infecting chimpanzees. Another open question was whether ape populations could serve as natural reservoirs for Plasmodium parasites.

Last year, US scientists from the University of Alabama at Birmingham revealed that the closest relations to modern human P. falci parum are not found in chimpanzees, but in western gorillas. Reporting their results in the scientific journal Nature (Vol. 467, pp. 420-425, Sept. 2010), the researchers analyzed almost 3,000 samples of ape feces using single genome DNA sequencing to identify Plasmodium species.

DNA sequencing showed that human “P. falciparum is of gorilla origin, not of chimpanzee, bonobo or ancient human origin”, the authors concluded. These data will help identify genetic changes in the parasite that allowed human infection, possibly revealing medical approaches to combating this disease. Combined with other relationship data from the study, it also seems that interspecies transmission is rare, and that modern apes are not a reservoir for the current human form of the Plasmodium parasite.

In fact, the researchers believe the parasite may have made the cross-species jump from gorillas to humans only once. Experts in the field find this information very encouraging for attempts to eradicate malaria. It suggests that if the human version of the parasite is eliminated, it could take thousands of years before another parasite jumped between species.

Malaria: Human parasite from gorillas


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In 1901, the Scottish bacteriolo-gist William Boog Leishman observed oval bodies in spleen samples from a patient who had died from dum-dum fever, pub-lishing these results in 1903. Also in 1903, Charles Donovan (1863-1951) working for the Indian Medical Service indepen-dently identified similar organ-isms in kala-azar patients. Roland Ross then linked kala-azar to these organisms – he called the

protozoan parasites Leishmania donovani, and the disease they cause became known as leishmaniasis.

Sir William Boog Leishman (1865-1926) studied enteric fever

and kala-azar while serving with the Royal Army Medical Corps in India. After returning to the UK, he became professor of pathology at the Army Medical College in 1900. This is where he developed a simple and efficient way to stain parasites in blood samples using a mixture of Methylene Blue and eosin. He also helped to work out the life cycle of the organism causing African tick fever, Spirochaeta duttoni, and developed an effective vaccine against typhoid.

Canine carriers

Leishmaniasis is transmitted by the bite of a female phlebotomine sandfly, a tiny insect found in sub-tropical and temperate regions throughout the world. Living in woods and surrounding areas, the flies lay their eggs in tree bark and burrows of small rodents. Moving more recently to urban areas, they choose aban-doned buildings, animal shelters, cracks in house walls, and household rub-bish. The disease is generally transmitted to humans from infected animals (zoonosis), and dogs are the main animal reservoir.

Protozoan parasites

The first clinical descriptions of “Aleppo boil” were made by Alexander Russell in 1756. The full etiology of the disease was described by Peter Borovsky, a Russian military surgeon work-ing in Tashkent on lesions called “Sart sore”. In 1898 he published details about the organism causing the symptoms, how it affected the host and correctly classified it as a protozoa.

Charles Donovan

R e t R o s P e C t I v e


n the 10th century Arabian physicians described in detail a

condition they called Balkh sore. It was also known as Aleppo, Baghdad and Orient Boil. In India they called it kala-azar, meaning black fever in Sanskrit. Although caused by the same protozoan parasites, kala-azar describes the less common, but more severe form of visceral leishmaniasis (VL). This affects vital organs such as the liver, spleen and bone marrow, and quite rapidly leads to death if untreated. The most common form, cutaneous leishmaniasis (CL), causes skin lesions, often on the face, and disfigurement for life. Centuries ago, Arabian doctors discovered that scratching such lesions with a needle and piercing this under the skin of

young girls protected those not yet affected. So long before Edward Jenner developed cowpox inocula tion, Arabian

girls were “vaccinated” in a non-visible region to prevent facial lesions, which would reduce their value in marriage.

History: Leishmaniasis

Accounts of lesions resembling leishmaniasis were written in the Middle East around the 7th century BC. In Ecuador and Peru disfigured faces appeared on pre-Inca pottery in the first century. The disease had many names, until the early 1900s when the parasite causing it was called Leishmania after the Scottish pathologist William Boog Leishman.

I

AnCIent sCULPtURe from Peru, which shows facial symptoms indicating leishmaniasis.

William B. Leishman

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Academy for educational Development (AeD)www.aed.org

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Phot

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GooD veCtoR MAnAGeMent is an essential part of integrated disease management. The bednet does provide a physical barrier between the blood-meal seeking female mosquito and the blood source under the net – the sleeper. But by touching the net with bodyparts to reach through, or finding holes in the net, the mosquito might still manage to bite. When the textile is treated with an insecticide, that chance comes close to zero. Nets alone reduce bites, but only treated nets reduce the disease: malaria!

public health journal 22 (2011)

Documents

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