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Pests

Dr. James ScottDivision of Occupational & Environmental

Health, Dalla Lana School of Public Health, University of Toronto

Asthma

• Prevalence of asthma increased by 75 % between 1980 to 1994 (US CDC)– Increase highest in children under 4 (160% ↑)

• 6 % of US population is asthmatic (1995)

• One third of asthmatics are under 18 y/o

• ↑ prevalence in urban areas, esp NE

• ↑ prevalence in males

• ↑ prevalence in blacks

Perzanowski MS et al. 2008. Allergic asthma. In: Bonnefoy X et al. (Eds). Public health significance of urban pests. Copenhagen: WHO.

• Up to 80% of mild or moderate asthmatic children are sensitized to at least one of the common indoor allergens, mainly cockroaches and dust mites

• Sensitization to mice, cockroaches and dust mites is seen in up to 15% of children as young as 2 y/o

Allergic sensitization

1. Sufficient Evidence for a

Causal Relationship

2. Sufficient Evidence for

an Association

3. Limited/ Suggestive

Evidence for an

Association

4. Inadequate/ Insufficient

Evidence to Determine if

an Association Exists

Support of Evidence Development

Clearing the Air, Washington DC: IOM (2000)

Summary of associations between damp/

mouldy indoor environment and health outcome

Exacerbation

dust mite

none

cockroach (children)RSV

cat, cow, horse, dog, bird, rodent, roach, mould, pollen, etc.

cat, cockroach, dust mite

dog, mould, rhinovirus

bird, RSV, URIs

cow, horse, rodent, endotoxin, pollen, insects...

Indoor pests

• Insects

– cockroaches

– bedbugs

– dust mites

– fleas and lice

• Rodents

– rats

– mice

Cockroaches

• Insects in the superorder Dictyoptera, order Blattaria

• Highly diverse group– about 3,500 scientifically described species of

cockroach

– up to 5,000 species are estimated to exist

– only a dozen species or so are peridomestic

• Wide range of ecology – most are omnivorous scavengers

– many species tend to form close relationships with other animals (e.g., inquilines)

Barcay SJ. 2004. Cockroaches, pp 121-216. In: Mallis's handbook of pest control, 9th ed. Moreland D (ed), Richfield, OH: GIE Media

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Human-associated cockroaches

A) German cockroach

B) American cockroach

C) Australian cockroach

D & E) Oriental cockroach (♀ & ♂)

Wikipedia: Blattaria

• Eat most things humans do– fond of starches, sugary things

and meats

– also eat cheese, beer, books, leather, hair, wallpaper, stamps, artwork, documents, postage draperies, rotting material

• Hide in small, dark crevices

• Produce a characteristic odour– called "attar" of roaches

– feces & abdominal scent glands

Cockroaches and public health

• Allergenic– ~40% of allergic asthmatics in the US are allergic to cockroach

– high levels of cockroach allergen in house dust are associated with increased emergency hospital admission for asthmatic kids

• Transmit pathogens– e.g. enteric bacteria in the genera Campylobacter, Clostridium,

Bacillus, Escherichia, Klebsiella, etc.

– act as vectors for food spoilage bacteria

– can transmit parasites (e.g., hookworm, round worm, tapeworm)

– possibly even transmit enteric hepatitis and poliovirus

• Detrimental psychological associations

Barcay SJ. 2004. Cockroaches, pp 121-216. In: Mallis's handbook of pest control, 9th ed. Moreland D (ed), Richfield, OH: GIE Media

Life cycle of a cockroach

Some terms:

• ootheca• ecdysis• eclosion• instar• holometabolous• hemimetabolous

Life cycle:

• females hide ootheca in protected crevices• (e.g., corrugated cardboard!)

• nymphs emerge in 38 d• completely developed in

6-12 m• life span is 1-1.5 y

David Resz, 2008

German cockroach nymphs and ootheca

wiki; http://entnemdept.ufl.edu/creatures/urban/roaches/american_roach_01.htm

c - cercis - styli

Adult male American cockroach, Periplaneta americana • Cockroach droppings– typically in concealed spots, like cracks and crevices,

common behind electrical covers

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Integrated Pest Management (IPM)

• Monitoring– identification, inspection, prediction, evaluation, decision

– "think like a cockroach"

• Eliminating entry points and attractive harborage

• Traps and baits– e.g., aggregation pheromones or white bread wetted with beer!

• Chemical flushing (pyrethrins)

• Spot treatment and broadcast chemicals– many are highly toxic organophosphates or carbamates

• Biological control– e.g., Beauveria bassiana, Metarhizium anisopliae, Gecko lizards!

Cockroach chalk– Chalk lines inside cupboards, along baseboards

– Contains deltamethrin• environmentally resistant neurotoxin

• strongly transdermal and passes into breast milk

Bed bugs

• True bugs in the order Hemiptera

– family Cimicidae contains bed bugs, bat bugs and bird bugs

• Common bed bug is Cimex lecticularis

• Obligate blood feeders– must take at least one blood meal during each

of 5 immature instars and to reproduce

– adults feed every 3-5 d and live 6-12 m

– adults can live for up to a year without feeding, nymphs can several months

Bonnefoy X et al. (Eds). Public health significance of urban pests. Copenhagen: WHO.

Scott Charlesworth, Purdue Univ

Bed bugs and public health

• Dramatic increase in bed bugs since the early 2000s– from Jan - Dec 2003, bed bug complaints and commercial pest

interventions in Toronto doubled (Emerg Infect Dis 11: 533-538, 2005)

– similar trend has been seen world-wide

• Explanations for increase include:– greater global travel for business and pleasure

– re-use of furniture and electronic devices

• Bed bugs can carry a number of human pathogens– in North America north of Mexico, they do not transmit disease,

causing only allergic irritation and psychological discomfort

– they do transmit Chagas disease in Mexico and South America

Bonnefoy X et al. (Eds). Public health significance of urban pests. Copenhagen: WHO.; Cooper RA & Harlan H. 2004. Ectoparasites, part 3: Bed bugs & kissing bugs, pp 494-529.

In: Mallis's handbook of pest control, 9th ed. Moreland D (ed), Richfield, OH: GIE Media

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Bed bugs and public health

• Allergenic– saliva contains enzymes that act as sensitizers and elicit

inflammation in atopic individuals

– can induce immediate-type or delayed-type hypersensitivity

– airborne allergen may also exacerbate asthma

Bonnefoy X et al. (Eds). Public health significance of urban pests. Copenhagen: WHO.; Cooper RA & Harlan H. 2004. Ectoparasites, part 3: Bed bugs & kissing bugs, pp 494-529.

In: Mallis's handbook of pest control, 9th ed. Moreland D (ed), Richfield, OH: GIE Media

Control

• Bed bugs are very difficult to control– small, nocturnal, mild bite, avoid chemicals, feed only periodically

• IPM– eliminate conducive conditions

• e.g., better ventilation, sanitation

– inspect / detect• traps, chemical flushing

– educate and modify behaviour• e.g., flea markets are called flea markets for a reason

– treat• e.g., heat (55°C for 3 hr), cold (0°C for 2 d), steam, pesticides

Cooper RA & Harlan H. 2004. Ectoparasites, part 3: Bed bugs & kissing bugs, pp 494-529. In: Mallis's handbook of pest control, 9th ed. Moreland D (ed), Richfield, OH: GIE Media

Dust mites• Visual assessment is possible for cockroaches and mice, but

not for dust mites because they're so small

• Best know allergenic mites are Dermatophagoides

pteronyssinus & D. farinae, but there are lots of other species

• “Dust mite” exposure is assessed by testing for specific mite-related allergens in house dust

• Dust is vacuum-collected and tested by ELISA

Perzanowski MS et al. 2008. Allergic asthma. In: Bonnefoy X et al. (Eds). Public health significance of urban pests. Copenhagen: WHO. Nature 463, 1079-1083 (2010) | doi:10.1038/nature08742

Arthropodphylogeny Insects

Mites are down here

Dust mite allergens

• Hundreds of different mite allergens have been described, but only a few are subject to routine testing– all are proteins, and many but not all are enzymes

– e.g., Der p 1 & Der f 1

– these allergens can be tested in dust, and sensitization can be assessed by skin testing

• The important mite allergens are contained in feces– Tovey et al, Nature 289: 592-593, 1981

• Sensitization in atopically predisposed people shows a dose-response relationship– Allergic response saturates at concentrations of dust mite

allergen >10 µg/g dust

Colloff MJ et al. 2009. Dust mites. Dordrecht: Springer

Mite biology

• Pyroglyphid mites– preferentially consume fungi and bacteria but can survive on

shed skin squames

– e.g., Dermatophagoides spp.

– only found in homes, not associated with industry

• Storage mites are associated with specific habitats– (e.g., Acarus spp. are found in poultry houses and granaries,

Tyrophagus spp. occur in cheese manufacture)

– these mites are generally not in houses but rather are associated with industrial processes where exposure to their feces and body parts may cause allergic symptoms

Colloff MJ et al. 2009. Dust mites. Dordrecht: Springer

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Colloff MJ. 2009. Dust mites. Dordrecht: Springer

Distribution of common house dust mites

Jorde W., Schata M., eds. Mönchengladbacher Allergieseminar Band 5. Innenraumallergene. Dustri-Verlag, München- Deisenhofen. 1993: 69-84.

Dust mite survival in Western Europe

We don't know, but the dust mite

distribution in Canada probably looks

something like this...

This is my best guess based on my experience with dust testing

No mite survival

Survival on poorly insulated

floors, no population growth

Survival all floors, no

population growth

Survival and population

growth on lower floors

Survival and population

growth on all floors

Control

• Sanitation– remove and discard old pillows, especially down-filled

– clean or discard contaminated plush furniture

• Prevention– lower the relative humidity

– install dust-mite covers on mattresses and pillows

Fleas

• Order Siphonaptera– holometabolous

– eggs laid on host but larvae live off-host

– can remain in cocoon up to 1 yr if needed

– adults live mostly on host, but can propel themselves (i.e. jump) great distances

• Ectoparasites of birds and mammals– blood-feeding, may cause significant blood loss

• Host specific but many can transfer hosts– e.g., cat flea can cycle on dogs & humans

• Cause irritation and transmit diseases

Hinkle N. 2004. Ectoparasites, part 1: Fleas & lice, pp 432-459. In: Mallis's handbook of pest control, 9th ed. Moreland D (ed), Richfield, OH: GIE; Media

Plague

• Caused by Yersinia pestis

– "Black Death", killed up to 30% of European population

– bubonic and pneumonic forms

– caused massive epidemics throughout antiquity

• Vectored by Oriental rat flea– Xenopyslla cheopis

• Still causes non-epidemic disease, e.g.:– plague cases in US southwest

– lab-acquired fatal infection in 2009 (Univ of Chicago)

Hinkle N. 2004. Ectoparasites, part 1: Fleas & lice, pp 432-459. In: Mallis's handbook of pest control, 9th ed. Moreland D (ed), Richfield, OH: GIE; Media; http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6007a1.htm

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Other flea-borne diseases

• Murine Typhus– caused by Rickettsia typhi

– vectored by Oriental rat flea

– usually produces a mild disease• fever, muscle & joint pain, nausea, vomiting, subset of patients develop

neurological symptoms

• often misdiagnosed

• Tapeworms– Dwarf tapeworm

• Hymenolepis nana, carried by Oriental rat flea

– Double pore dog tapeworm• Dipylidium caninum, carried by the cat flea

• infects both dogs and cats, and can infect children who ingest infected fleas

http://extension.entm.purdue.edu/publichealth/insects/flea.html Scott Charlesworth, Purdue Univ

Control by IPM

• inspection and detection

• sanitation, remove conducive conditions

• flea exclusion– remove susceptible hosts

• suppress fleas for 1 wk prior to killing pest hosts (e.g., rats) otherwise displaced fleas will seek human hosts

– physically remove fleas from pets using flea comb

– environmental traps

• pesticides– flea suppression on reservoir hosts

– poison baits

– broadcast pesticides

Hinkle N. 2008. Fleas. In: Bonnefoy X et al. (Eds). Public health significance of urban pests. Copenhagen: WHO.

Lice

• Order Phthiraptera– hemimetabolous

• Ectoparasites of birds and mammals– obligate blood-feeders that live entirely on host

• Three lice attack humans– Pediculus humanus humanus -- body lice

– Pediculus humanus capitis -- head lice

– Phthirus pubis -- public lice

• Historically known as disease vectors– epidemic typhus, trench fever, louse-borne

relapsing fever

– now mostly just associated with social stigma (but cost a lot of money!)

Burgess I. 2008. Human body lice. In: Bonnefoy X et al. (Eds). Public health significance of urban pests. Copenhagen: WHO.

Weiss RA. 2009. Apes, lice and prehistory. J Biol 8:20.Reed DL et al. 2007. Pair of lice lost or parasites regained: the

evolutionary history of anthropoid primate lice. BMC Biology 5:7.

How we inherited our lice

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Body louse

• Now mainly associated with poverty– also encountered in the setting of civil disruption (e.g., war,

natural disaster, etc.)

• Lives in clothing seams rather than on the body– lays eggs in clothing seams

– visits the host to feed

• Can only live ~2 d without a blood meal

• Very sensitive to temperature and moisture– e.g., readily killed by heat at 50°C for 20 min

Burgess I. 2008. Human body lice. In: Bonnefoy X et al. (Eds). Public health significance of urban pests. Copenhagen: WHO.

Control

• Inspection and detection

• Physical removal– louse comb

– "nit picking"

– heat treating garments and bedding

• Pesticides

Burgess I. 2008. Human body lice. In: Bonnefoy X et al. (Eds). Public health significance of urban pests. Copenhagen: WHO.

Arthropods and dampness

isopods

silverfish

weevils

housecentipedes

Rodents

• Over 2,200 species world-wide– most diverse order of placental mammals (33 families)

– account for about half of placental diversity

• Several dozen rodent species are peridomestic pests– most notably rats and mice, but also marmots, beavers,

porcupines, rabbits, etc.

– mostly considered "kleptoparasites", destroy or steal food and equipment

– rats and mice are highly allergenic and transmit a wide range of diseases

Corrigan M. 2004. Rats & mice, pp 11-119. In: Mallis's handbook of pest control, 9th ed. Moreland D (ed), Richfield, OH: GIE; Media

Phylogeny of

Rodents

BMC Evolutionary Biology 2009, 9:71

Norway rat• Rattus norvegicus

– also called the brown rat, sewer rat or wharf rat

– most important urban pest in most parts of the world

• Origin– not from Norway but rather Central Asia

– now very widespread• more widely distributed than the black rat which it largely displaced

• Biology– more adapted than the black rat to flat, treeless habitats

– distinguishing feature is that the tail is shorter than the body

– high fecundity • up to 12 litters/yr with up to 22 pups/litter

• female can mate within 18 hr of giving birth

• pups reach sexual maturity in 2-3 months

Battersby S. 2008. Commensal rodents. In: Bonnefoy X et al. (Eds). Public health significance of urban pests. Copenhagen: WHO.

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Roof rat

• Rattus rattus

– also known as the ship rat, black rat, house rat

• Ecology and distribution– originally a sylvan species from Southeast Asia

– underwent a diaspora along trade routes across India and around the Mediterranean, entering Europe by the 12th century

– range is much more restricted than that of the Norway rat

• Biology– responsible for epidemics of Black Death during the middle ages

– excellent climber and jumper, will live in trees

– distinguishing feature is that tail is longer than body

– less aggressive than the Norway rat and not as carnivorous

Battersby S. 2008. Commensal rodents. In: Bonnefoy X et al. (Eds). Public health significance of urban pests. Copenhagen: WHO.

Rat-borne diseases

• Murine typhus

• Plague

• Salmonellosis

• Leptospirosis

• Trichinellosis

• Toxoplasmosis

House mouse• Mus musculus

– (Mus, is from Sanskrit verb "to steal")

• Originated in Central Asia but now exist everywhere

• Biology– One female can produce up to 10 litters in her lifetime

• gestation is 18-21 days

• can produce litters at 30-50 day intervals with each litter containing 2-13 mice (average 5-6), yielding up to 60 offspring/yr

– Mice can survive very long periods without water• unlike rats, they can generate metabolic water

• Health considerations– produce copious amounts of allergen in their urine

– mark microdrops urine along scent trails, like an inkjet printer

Battersby S. 2008. Commensal rodents. In: Bonnefoy X et al. (Eds). Public health significance of urban pests. Copenhagen: WHO. http://www.ci.berkeley.ca.us/Health_Human_Services/Environmental_Health/Control___Preventions_of_Rodents.aspx

Rodent gnawing damage

http://www.aaanimalcontrol.com/ratgallery.htm

Corrigan M. 2004. Rats & mice, pp 11-119. In: Mallis's handbook of pest control, 9th ed. Moreland D (ed), Richfield, OH: GIE; Media

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Control by IPM

• Identify and monitor

• Exclusion– remove or restrict harborage areas

– eliminate entry points

• Sanitation

• Bait and trap– rats can be very picky eaters and they don't like unfamiliar food

– mice are more adventurous about eating unfamiliar things

• Rodenticides

• Rodent traps

http://www.aaanimalcontrol.com/ratgallery.htm

• Rodent poison bait