r4d.dfid.gov.uk pdf outputs livestock 60877-dfid final25!9!2011

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Zoonoses(Project1)

Wildlife/domesticlivestockinteractions

AfinalreporttotheDepartmentforInternationalDevelopment,UK

Submittedby:

TheInternationalLivestockResearchInstitute,Nairobi

&

RoyalVeterinaryCollege,London

Reporteditors:DeliaGraceandBryonyJones

Reportauthors1

BryonyJones DeclanMcKeever DeliaGrace DirkPfeiffer FlorenceMutua JemimahNjuki JohnMcDermott JonathanRushton MohamedSaid PollyEricksen RichardKock SilviaAlonso(Researchassistants:JarrahYoungandPernillevanGrieken)

Date:

September25th

2011

1Inalphabeticalorderoffirstname


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Contents

1. Executivesummary............................................................................................................................3

2. Methodology....................................................................................................................................11

3. Importanceofzoonosesandthelivestockwildlifeinterface..........................................................15

4. Mappingzoonosesatthelivestockwildlifeinterface.....................................................................26

5. Diseasetransmissionroutesandtherelativeimportanceofthewildlifelivestockroute..............33

6. Pathogensofwildlifecapableofrecombiningwithanalogousorganismsindomesticlivestock...41

7. Riskfactorsfordiseasetransmissionfromwildordomesticanimalstopeopleandbetween

wildlifeanddomesticlivestock.............................................................................................................51

8. Driversinfluencingtheinteractionbetweenwildlifeandlivestockandtheimplicationsfor

zoonosestransmission..........................................................................................................................58

9. Historicalchangesintransmission,factorswhichfosternoveltransmissionroutesandhosts,and

wildanimalcandidatesforfuturediseasetransmission......................................................................68

10. Keyfactorsinfluencingtheriskofthetransferofinfectionsbetweenlivestockandwildlifein

developingcountries:productionandsocioeconomicfactors...........................................................88

11. Managementofzoonosesatthelivestockwildlifeinterface........................................................95

References..........................................................................................................................................111

Annex1.AssumptionsaroundDALYcalculations...............................................................................126


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1. Executivesummary

Theobjectiveofthisstudywastosynthesisethebestavailablescientificknowledgeaboutzoonotic

diseasetransmissionthroughlivestockandwildlifeinteraction(directorindirect),withemphasison

risk factors, drivers and trajectories of transmission, as well as promising interventions for

controllingimportantzoonoses,basedonmanagingtheinteractionbetweendomesticlivestockand

wildlife.

Amultidisciplinaryteam fromthe InternationalLivestockResearchInstitute,Kenya,andtheRoyal

VeterinaryCollege,UnitedKingdom,withexpertiseinzoonoses,epidemiology,socioeconomics,and

wildlife,undertookthereview.Adatabaseofimportantzoonoseswascompiledandusedtodevelop

a list of priority zoonoses with a livestockwildlife interface for developing countries. Spatial

relationships between important zoonoses and land use and human population density were

explored.Asystematicreviewwascarriedout focussingon:diseasetransmissionroutes,riskfactors

fordisease transmission,driversofwildlifelivestock interactions,pathogensofwildlifecapableofrecombining with organisms in livestock, wildlife species that are potential sources of zoonotic

pathogens, production and socioeconomic factors influencing the risk of transmission, and risk

management and control interventions. The main findings are summarized in this executive

summary.

Zoonosescanbebroadlydefinedasdiseasesthatarenaturallytransmissiblebetweenanimalsand

people.Zoonosesareofconcernfortwomainreasons;thehealthandeconomicburdenscausedby

zoonoseslongknowntocausediseaseinanimalsandpeoplethatpersist invulnerablegroups,and

the potential for emerging zoonoses to give rise to novel disease outbreaks. The burden of

persisting

zoonoses

is

mainly

borne

by

poor

people

in

developing

countries,

whilst

emerging

zoonosesareofmoreconcerntotherichindevelopedcountrieswithlargereconomiesandfewer

otherinfectiousdiseaseproblems.

Aszoonosesarebydefinition transmissiblebetweenanimalsandhumans, it isnotsurprising that

most are also transmissible between wildlife and domestic animals. Transmission depends upon

contact (direct or indirect) between livestock, domestic animals and people and transmission

opportunities are subject to various, sometimes opposing drivers. The unprecedentedly large

human population and the associated increases in demand for land, food (and use of natural

resourcesistherootcauseofincreasedtransmissionopportunities.However,developedcountries

havehighanimalandhumanpopulationsbutzoonosesareoflowhealthsignificancesuggestingthe

high level of zoonoses in developing countries is not due to absolute population size but other

factors. These could include the speed of increase in human and animal populations driving a

livestock revolution2 with rapid yet poorlyregulated changes in livestockkeeping systems, and

massiveintensificationinparallelwithcontinuedhighlevelsoflivestockownershipandclosecontact

betweenhumansandlivestock.However,theorigin,distributionandimpactofemergingzoonoses

islessskewedtowardspoorcountriesthanisthecaseforpersistingzoonoses.

2TheLivestockRevolutionistherapid,demanddrivenincreaseinlivestockproductionandtradeindevelopingcountries.


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Threeimportantproximaldriversofincreasedzoonosestransmissionandextensionofthelivestock

wildlife interfacearerapidly increasing livestocktrade,agriculturalexpansionwith incursion into

newareas,andculturalconsumptionpractices(especiallyconsumptionofbushmeatinAfricaand

Asianforbuyingfromwetmarketsselling livedomesticanimalsandwildlife inAsia). Indeveloped

countries,recreationandconservationcan leadto locally increasedriskbuttheassociateddisease

burdenisnotimportantincomparisontoothercausesofsicknessanddeath.

Agriculture intensification is not always a risk amplifier but the rapid and poorly regulated

intensificationassociatedwiththelivestockrevolutionindevelopingcountries,is.Whileincreasing

thenumbersof livestockkeptwillof itself increaserisk,theeffectsof intensificationare lessclear.

Highlivestocknumbers,highstockingdensities,poorhusbandry,andinappropriateuseofantibiotics

associated with intensification in developing countries all favour disease transmission and

emergence. However, reductions in the proportion of the population keeping livestock,

improvements inbiosecuritythatareeasierto implementandregulateon largefarms,andbetter

surveillance and disease control are characteristics of agriculture intensification in developedcountries and are risk mitigating. On the other hand, the increasing genetic homogeneity of

livestockassociatedwith intensification(monoculture) inbothdevelopedanddevelopingcountries

isprobablyanimportantfactorinspreadandamplificationofdisease.

For both persisting and emerging zoonoses, it appears that a broad range of pathogens can be

acquiredfromamanydifferenthostsunderawiderangeofcontexts,whichmayormaynotinvolve

awildlifelivestockinterface.Itisespeciallydifficulttomakepredictionsaboutthefewandunusual

emergingpathogensthatgoontohavemassiveimpact.MadcowdiseaseinBritainsadvancedwell

regulateddairy sector, SARS3with links towildlife inAsiasbusywetmarkets,avian influenza in

intensiveand littleunderstoodproductionsystems inChina,andRiftValleyFeveremerging in low

density,traditionallivestocksystemsinAfricahavefewcommonfeatures,althoughallfourdiseases

havealivestockwildlifeinterface.Thedifficultyofgeneralisingfromsmallnumbersofcasesmeans

that predicting high impact zoonoses is challenging. Nonetheless, some hotspots in terms of

geographicareasandonestowatch intermsofpathogensandhostscanbetentativelyidentified

andtheseshouldbesubjecttohighersurveillancealongwithevaluationofthecostsandbenefitsof

thisrisktargeting.

In developed countries, management of persisting and emerging zoonoses has been relatively

successful (although often expensive). Successful control is less likely where wildlife have a

substantialroleintransmission.Eliminationofwildlifepopulationsisgenerallynotafeasiblecontrol

strategy; reducing wildlife numbers can be useful but smallscale and shortterm programs are

generally ineffective andmaybeharmful;physical separationof livestock andwildlife isdifficult,

expensiveandcanhaveunwantedsideeffects.Inpoorcountries,managementhasbeenmuchless

successful.However, thehistorically recent,massive,unplanned reduction inwildlifepopulations

especially inAfricanandSouthAmericahasaffectedzoonosesprevalence,positivelyornegatively

dependingonthecontextandtemporalscale(ecosystemincursionoftenincreasesriskintheshort

term,whiledecreasing in the long term).The major deficit in current management of zoonoses

3SevereacuterespiratorysyndromeisarespiratorydiseaseinhumanswhichiscausedbytheSARScoronavirus


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withalivestockwildlifeinterfaceisthatprogrammesarenotbasedonadequateepidemiological

orsocioeconomicunderstanding.

Inthenextsectionwesetoutthekeymessagesidentifiedbyexperts inthisstudyalongwiththeir

strength of supporting evidence, and identify the associated evidence gaps and the possible

contributionofresearch.Thequestionsarethosesetoutinthereviewtermsofreference.

What is theextentof theproblemofzoonoses, the contextand the relative importanceof the

wildlife/domesticlivestocktransmissionroute?

Zoonoses are absolutely and relatively more important in lowincome countries compared tohighincomecountries(evidencestrong Chapter3).Inlowincomecountries,infectiousdiseases

areresponsiblefornearly40%oftheburdenofhumansicknessanddeath,and onefifthofthisis

attributable to zoonoses or diseases recently emerged from animals, with recently emerged

disease (mainlyAIDS4)abouttwiceas importantaszoonoses (evidencemedium Chapter3). In

highincomecountries, infectiousdiseasesaremuch less important (4%oftotalburden).Whilediseasesemergingrecentlyfromanimalsandfoodbornezoonosesareanimportantpartofthis

smallburden,otherzoonoseshaveminor impacts(Evidencestrong Chapter3).Manyofthese

zoonoses,inbothrichandpoorcountries,havealivestockwildlifeinterface.

Thetotalimpactofzoonoseswithalivestockwildlifeinterface,goesfarbeyondhumansicknessanddeathandincludesmultipleotherburdens,suchas:monetarycostofillness;costtolivestock

sector;opportunitycosttoeconomies;negativesocialandpsychological impacts;and,negative

impactsonwildlifeandecosystems(Evidencestrong Chapter3).

TheGlobalBurdenofDiseaseassessment ledbytheWorldHealthOrganisation(WHO)suggestsfoodbornezoonoses,humanAfricantrypanosomosisand leishmaniasisarethemost important

zoonosesgloballyallhavealivestock/wildlifeinterface(evidencemedium Chapter3).

Publishedexpertopinionconsidersbrucellosis,humanAfrican trypanosomosisandtuberculosisto be the most important zoonoses all have a livestock/wildlife interface (Evidence weak

Chapter3).

Inthestudyconductedforthisreport,weidentified292importantzoonosesfromtheliterature:82%ofthesehadawildlifereservoir,74%hadadomesticanimalreservoirand60%hadbotha

wildlifeandadomesticanimalreservoir(Evidencemedium Chapter3).

Keyevidencegaps:

There isa lackofsystematicsurveillancedataforzoonoses ingeneral,andforzoonoseswithalivestockwildlife interface inparticular.Studiesareneededtodeterminepresence,prevalence,impactsandriskfactors.

Thereislackofevidenceonthemultipleburdensofzoonoticdiseaseandmeasuringtheburdensand mapping the occurrence of zoonotic disease is a first step for prioritization and rational

management inresourcescarcecontexts.Many importantzoonosesaremissingfromtheWHO

GlobalDiseaseBurdenwhich isnowthe leadmetric forguidinghumanhealth interventions; in

addition complementary metrics are needed to capture economic, social and environmental

burdensofdisease.

4Acquiredimmunedeficiencysyndromeoracquiredimmunodeficiencysyndrome(AIDS)isadiseaseofthehuman

immunesystemcausedbythehumanimmunodeficiencyvirus(HIV)


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Thereisalackofevidenceontheapplicationofinnovationstosurveillance,modellingandgeospatialmappingwithpotentialtoimproveassessmentandhencemanagement.

Possibleresearchcontributions

Crosssectionalstudiestomappresenceandprevalenceofimportantzoonoses. Burdenofdisease(DALYs)estimatesforneglectedandhithertounmeasuredzoonoses. Metricsthatcapturetheotherimpactsofzoonoses(multipleburdensofdisease). Frameworksforprioritisationforinvestmentinzoonoses(researchanddevelopment). Novelrapidandlowcostdiagnosticssuitableforfielduse. Surveillancesystemsthatuseinnovativeapproachese.g.riskbased,participatory,mobilephone,

HealthMap,molecular,etc.

Surveillancesystemsthatimprovelinksbetweenhuman,livestockandwildlifediseasedata. Betterlinkingofsurveillancetoaction. Rigorousimpactassessmentsofdifferentsurveillancemodelsincludingaccordingtoestablished

frameworkse.g.CDC.

Prioritisation of research on wildlife origin zoonosis and key species presence/prevalence todeterminerisk.

Whichwildlife specieshavebeen implicated in the transferofdiseasefrom livestock tohumans

andwhatarethekeyfactorsthatinfluencetheriskoftransmission?

Manydifferentwildlifespeciesare implicatedashostsforthe importantzoonoses identifiedbyourstudy(n=292).Ofthehosts(663)listedinourdatabase,51%weredomesticatedanimalsand

36%werewildanimals,withtheremainderbeingunspecifiedorlikelytoincludebothdomestic

and

wild

species

(e.g.

hosts

listed

as

birds

or

herbivores)

(Evidence

weak

Chapter

3).

There are few studies on risk factors for transmission from wild and/or domestic animals topeople and between wildlife and domestic livestock in the literature, and studies are biased

towardscertainspeciesandorders(evidencestrong Chapter7).

Consumptionofbushmeatrepresentsoneofthemoresalientways inwhichhumanscome inclosecontactwithwildlifeandtheirpathogens.Itisanimportantsourceofzoonotictransmission

fromwildlife(Evidencemedium Chapter5).

Environmental contamination with pathogens by livestock and/or wildlife is another majortransmissionroute(evidencemedium Chapter5).

Agroecosystemchange,especiallyforestfragmentationandedgeeffects,canincreasepathogenflowsbetweenpeople, livestockandwildanimals,and increasediseaserisk (Evidencestrong

Chapters5,7and8).

Agroecosystem change can also decrease disease risk, and a shift from wildlife to domesticanimalhostscanselectfordecreasedpathogenicity(Evidencemedium Chapter7).

Socioeconomic determinants of health can be more powerful determinants of risk thanbiologicalfactors(Evidencemoderate Chapter7).

Whetherthereareotherwildlifespeciesthatcouldbecomekeycandidatesfortransferofdisease

inthefutureandwhy?

Viruses

are

more

likely

to

be

emerging

than

other

types

of

pathogen.

A

wide

host

range

is

associatedwithpathogenemergence(Evidencemedium Chapter9).


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Dataonmultispeciespathogentransmissionandadaptationofvirusesislimitedtoafewfamilies,mostlyRNAviruses:notablycoronaviruses, lentiviruses, flaviviruses,paramyxovirusesandavian

influenzaviruses(Evidencestrong Chapter6).

Theputativeoriginalhosts forthesevirusesare:bats (3viruses),primates (2viruses)andcats,cattle, horses, birds and rabbits (1 virus each). However, there are many other potential

candidate pathogens and hosts, that have not been properly evaluated. (Evidence medium

Chapter6).

Whilemanyorganismshavethepotentialto infectmanyspecies,thekeytochanges indiseasetransfer is contact rates and host opportunities (often anthropogenically driven) (Evidence

medium Chapter6).

Batshaverecentlybeenthesourceofanumberofemergingzoonoticdiseases,someofwhichhaveinvolveddomesticanimalsintransmissionandamplification.Encroachmentofhumansand

livestock into bat habitat and disturbance of bat populations due to hunting and habitat

destruction,aswellasbatbehaviouranddemography is increasing the likelihoodofpathogen

spilloverandfuturediseaseemergence.(Evidencemedium Chapter9).

Keyevidencegaps

Many zoonoseshavemultiple transmission routesandmultiplehost reservoirs thatarepoorlyunderstood;assessingthe importanceofdifferenttransmissionroutesandtherolesofhosts in

specificcontextsisaprerequisiteforeffectiveandefficientcontrol.

Lack of understanding of the human behavioural determinants of livestock and wildlifeinteraction and exposure through, for example, hunting, harvesting, consumption, recreation,

andagriculturalintensification.

Lackofevidenceonputativetransmissionhotspots,including;livestockmarkets;urbanandperiurbanwildlifeand farming; fragmentsandedges;wildlifeconservationareasandbufferzones;

wildlifevaluechains;aswellasdynamichotspotscausedbynaturaldisastersandconflict.


Reviewsofexistingevidenceonattribution,transmissionroutesandepidemiology. Conventional and molecular epidemiology to map pathogen flows, especially in suspected

hotspots(staticanddynamic).

Wildlifesurveystodetectpathogensandhostranges,focusingonthespeciesandpathogensthatshow greatest potential for zoonotic transmission and emergence (peridomestic species,

rodents,bats,viruses). Transmissionexperimentstounderstandinfectivityandhostranges. Case control and risk factor studies to investigate links between human illness and livestock,

wildlife,food,waterandotherfactorsincludingsocioeconomic,toinformdiseasemanagement.

Human behavioural and socioeconomic studies to understand the institutional environmentwithin which people make decisions and the underlying anthropogenic drivers of disease

transmission.

Modelling(multidimensional,interdisciplinary)tobetterunderstanddiseasedynamics. Applicationofvaluechainanalysistowildlife,foodandproductsystems. Surveyofperidomesticattributesthatare importanttobringingwildlife incontactwithpeople

andlivestockandassessmentofrisks.


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Whatarethemaindrivers(globalandgenericwithinregions)changingthedegreeofinteraction

betweenwildlifeanddomestic livestock andwhat are the key characteristics (e.g. geographic,

political, economic, demographic, gender etc) which they affect in influencing the risk of

transmission?

Thegrowth inhumanpopulationandconsumption isdrivingwidespreadenvironmentalchange(urbanisation,agriculturalexpansionand intensification,andwildlifehabitatchange),whichhas

led to zoonoticdisease emergence and reemergence.However therehavebeen few studies,

(and fewer in developing countries), that quantify or identify causal links for this probable

association.(Evidencemedium Chapters5,6,8,10).

Changing landuseandagriculturalexpansiondisruptswildlifehabitatsandbringshumansandtheir livestock into closerproximity towildlife resulting in changes inhostpathogendynamics

andincreasedriskofspillover.(Evidencestrong Chapters5,6,8,10).

Livestock production intensification increases the population and density of livestock andincreases the likelihoodof livestockbecoming an amplifyinghost,or sourceofenvironmentalcontamination.(Evidencemedium Chapters8,10).

Livestock and wildlife movements, marketing and trade increase the risk of local andinternationalmovementofpathogensandspillovertohumans.(Evidencestrong Chapters5,8,

10).

Wildlifemanagement forconservationor recreationalhuntingcan increase thepopulationsizeanddensity resulting inhigherdiseaseprevalence inwildlifeand increased riskofspillover to

livestock.(Evidencemedium Chapters5,8).

Disease emergence is influenced by human behaviour including decisions driven by lack ofinformationandrulebreakingbehaviour.(Evidencemedium Chapter10).

Climate change ispredicted toaffect thegeographicaldistributionandpopulationdensitiesofwildlifespecies,whichwill interactwithmanyother factorstohavevariableeffectsondisease

dynamics.(Evidenceweak Chapters8,9).

OthercommonlycitedfactorsthatinfluenceemergenceorreemergencewithvaryingdegreesofevidencearedetailedinChapter9;theseinclude:deteriorationofpublichealthservices,human

migrants (often associated with war and conflict or disaster), urbanization, natural disasters,

globalization,watermanagementprojects,useof fertilizers,deforestation, lossofbiodiversity

andextremeclimaticeffects.(EvidenceweaktomediumChapter9).

It is the context in which potential pathogens exist and evolve that matters most to diseaseemergenceandnotmolecularmechanisms,whichhavealwaysexistedandareprimed to takeadvantageofopportunitiesastheyarepresented(Chapter6).

Keyevidencegaps

Morestudiesofcontextualaspectsofthewildlifelivestockinterfaceareneeded,andondriverswithinspecies(susceptibilities)forpathogenevolutionandamplification.

Work isneededonunderstandingmore specificallyhow thechangingbiomassofhumansanddomesticanimalsandbiodiversitydeclinewillaffectpathogenemergenceandevolution.

Thereislimitedunderstandingofrapidlychanginginstitutionalenvironmentswherepeoplefromruralandurbanareasandnationaland internationalgroupsaremixing,and rule systemsand

their associated enforcement (household, community, private, legal) are constantly being


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modified with pockets of activities that are poorly monitored, allowing for rule breaking

behaviour.


Frequencyandlikelihoodofpathogenflowacrossspeciesunderdifferentcontexts. Keyecologicalchangeswhichdrivepathogenemergenceandtransmission. Specificresearchintomechanismsofamplificationandpersistence. Longitudinalstudiestounderstandchangesindynamicsovertime. Researchintonaturaldiseaseandinfectionprocessesinbiodiverseanimalcommunitiesandhow

thesesystemsselectforandmaintainlowpathogenicitymicrobialcommunities.

Foresight ormodelling to understand possible trajectories of disease dynamics in the face ofanthropogenicdriverssuchasclimatechangeanddemography.

Developingwaysofquantifyingtheanthropogenicdriversofchangesindiseasedynamics. Groundtruthingassumptionsaroundimpactsofdriversonemergence. Developmentofmethodsforassessingruleandenforcementstructuresacrossfoodandproduct

systems

What are thepossible interventions (and associatedgovernance structure) that could limit the

interactionofkeywildlifespecieswithdomesticlivestockandthepotentialeconomicandsocial

impacts(atbothstateandhouseholdlevel)ofthoseinterventions?

a)Whatistheevidenceregardinginterventionmethodsthatreducecontactbetweenwildlifeand

livestock?

Riskfactorsarecontextspecific,andtheeffectivenessofan interventionstrategywillvarywithcontext. Interventions based on risk are more effective and efficient than conventional

management.(Evidencemoderate Chapter7).

Eliminationofwildlifepopulationsasameanstoreducecontactisnotdesirableandinanycaseprobablynotfeasible(Evidencemoderate Chapter11).Reducingwildlifepopulationcanreduce

risktolivestock,butsmallscaleandshorttermcontrolisineffectiveandcanevenspreaddisease

(Evidencestrong Chapter11).

Separationoflivestockfromwildlifebyfencinggenerallyreducesrisksofdiseasetransferbutthelossofheterogeneityinthelandscapeincreasesriskofstochasticdiseaseeventsthroughlossof

endemism and immunity. Few barriers are impermeable. Environmental, social and economic

costsoffencingarehighandunacceptableincountrieswithstrongwildlifeeconomiesandwith

migratingwildlife.(Evidencestrong Chapter11).

Innovationsmayradicallyimprovecontroleveninpoorcountries.(Evidenceweak).b)Associatedgovernancestructures

Both topdown and communitybased programs have had little longterm success in tacklingepidemiologically complex disease at the humanlivestockwildlife interface in developing

countries(Evidencemedium).

IntegratedandOneHealthapproachesleadtobettercontrol(Evidenceweak/medium). Propoordevelopmentisoneofthemosteffectivewaysofreducingzoonoses(Evidencestrong).Keyevidencegaps


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Currentassessmentandmanagementis,forthemostpart,notbasedongoodsurveillanceorriskdata.Riskbasedmanagementoffersagreatopportunityforimprovingmanagementofzoonoses.

Thisinvolvesbasingmanagementoncontextspecificepidemiologyandriskfactors.

Peoples reaction to thepresenceof disease is inadequatelyunderstoodmaking itdifficult totailorinterventionsthatcreatesynergiesforhouseholdandcommunityactions.

Thecosts,benefitsandbroaderimpactsofzoonosesmanagementareimperfectlyunderstoodaswellastheincentivesneededforsustainablecontrol.

Adapting innovations: promising technological, organizational and social innovations exist butneedtobebetteradaptedtodevelopingcountrycontexts.


Systematicreviewstoidentifyinterventionsforwhichcredibleevidenceexists. Identifyingriskfactorstoguidezoonosesmanagementinspecificcontexts. Developing integrated interventionpackages to target risk factors, incorporating technological,

socialandeconomicinnovations.

Randomisedcontrolledtrialsofinterventionpackagesassessingefficacy,appropriateness,equity,sustainabilityandimpactsofinterventions.

Developmentofadatabaseonlocalandcommunityresponsestodiseasepresence. Comparing successful and failed interventions in order to develop guidelines for policy and

practice.

Economic and social experiments to better understand incentives arounddisease control andsustainability.

OneHealthmethodsforlinkingdifferenttypesofinterventions.

Socio

ecological

approaches

to

determining

optimal

control

methods

based

on

reducing

risk

and

increasingresilience.

Research intonovelcontrol technologiesandapproaches suchasvaccines,population control,diseaseresistance,biosecurity,husbandryandecosystembasedinterventions.

Modellingofdifferentcontroloptions(epidemiology,ecology,economics).

Note:Thestrengthofevidencesupportingthevariousstatementsisassignedbyexpertsresponsible

forthereviewusingcriteriasetoutinthemethodology.


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2. Methodology

Overview

Amultidisciplinaryteam fromthe InternationalLivestockResearchInstitute,Kenya,andtheRoyal

Veterinary

College,

United

Kingdom,

with

expertise

in

zoonoses,

epidemiology,

socio

economics,

and

wildlife,undertookthereview.Adatabaseofimportantzoonoseswascompiledandusedtodevelop

a listofpriorityzoonoseswitha livestockwildlife interface fordevelopingcountries.Collaboration

withHealthMap andAUIBARpermittedinitialexplorationofspatialrelationsbetweenzoonosesof

importance, landuse andhumanpopulationdensity.A systematic reviewwas carriedout in line

withthescopesetoutintheTermsofReference.

Identificationofzoonoseswithawildlifelivestockinterface

We considered that zoonoses appearing in standard textbooks couldbe classified as important.

Thisisanimportantpointofdeparturefromotherstudiesthatincludeallzoonoticpathogens,even

those that are extremely rare. One of our hypotheseswas that important zoonoses might have

differentcharacteristics intermsoftypeandhost.Threestandardtextbookswereusedto identify

these zoonoses of importance (PAHO, 2003, Goldsmid, 2005, MVM, 2008). Information was

extracted from the textandentered intoanExceldatabase. Initially343diseaseswere identified,

which reduced to 292 diseases after removing duplicates and standardising names. The disease

name, the specific causative agent, type of agent (bacteria, virus, protozoa, helminth, fungus,

arthropod,other), region (developing,developed), reservoirs (wildlife,domestic), andhostswere

recordedforeachdisease.

Fromthedatabaseof292 importantzoonoses,theresearchteamselected61zoonosesthatboth

hadalivestockwildlifeinterfaceandwereimportantindevelopingcountries.Additionalinformation

wasaddedtothedatabaseonthemode(s)oftransmissionforeachdiseaseandtheinvolvementof

largemammals.

Mappingofzoonoses

Weinvestigatedtheuseofwebbasedmappingandgeoreferencedmapsformappingdiseasesand

relating the spatial distribution of disease to human demography, environment (land cover) and

wildlife distribution. One webbased disease mapping system that we explored was HealthMap

(www.healthmap.org),whichisanautomatedsystemthatgathersinformationfordiseaseoutbreak

monitoringandrealtimesurveillanceofemergingpublichealththreatsfromnontraditionalsourcessuchasonlinenewsoutletsandexpertdiscussionforums,aswellasgovernmentwebsites(Major,

2008). HealthMap was developed as a freely accessible and automated system that monitors

information on emerging diseases in real time. It currently gathers reports from 14 sources,

includingGoogleNews,whichsummarisesinformationfrommorethan20,000differentwebsites.It

uses search criteria that includediseasenames, symptomsand keywords.The system collectsan

averageof300reportsperday,mostofwhich(85%)comefromnewsmediasources(Major,2008).

Outofthelistofdiseases,diseasesyndromesortypesofdiseaseforwhichHealthMaphaddatawe

requested dataforAfrica on15zoonoticdiseasesordiseasesyndromesortypesthatweremainly

zoonotic fortheperiodofJanuary2006toApril2011.Thediseasesandsyndromeswereanthrax,avian influenza, botulism, bovine tuberculosis, brucellosis, Clostridium difficile infection,


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Cryptosporidium,diarrhoea,dysentery,foodborne illness,gastroenteritis, leptospirosis,salmonella,

trichinosis,andwaterborne illness.HealthMap provideddataondiseaseoutbreakbydiseasetype,

globalpositioningsystem(GPS)coordinatesandsourceofinformation.

Wegeneratedmapsofindividualzoonoticdiseasesandspeciesrichnessforall15zoonoticdiseases.

Thespeciesrichnessmapwasderivedbyaddingdiseasesoutbreaksinanareaofonebyonedegree

grid.Thesemapswereoverlaidwithhumanpopulationmaps andwederived statistics from the

numberofpeoplethatwerewithintheareaofdiseasesoutbreaks.Nextweoverlaidwithprotected

areas to find how many outbreaks occurred inside and outside protected areas. The human

populationdatawassourcedfromILRIanddataontheprotectedareasfromWDPA(WDPA,2010).

EvaluationoftheHealthMapdatabaseindicatesthatanumberofdiseasesdidnothavefullcoverage

for the period used in this study, which may be because HealthMap relies on reported disease

outbreak information from theprintmedia (Major, 2008).BetweenOctober2006 to July 2007 a

wide variety of pathogens were detected with information on 141 unique infectious disease

categories that was based on data sourced from Google News feed alone (Major, 2008). The

pathogensmostreportedwereavianinfluenza(877reports),Escherichiacoli(733),andSalmonella

spp. (479). Over the study period reports of outbreaks of infectious disease occurred in 174

countries,with the greatest number from theUnited States (4351 reports), theUnited Kingdom

(1018), Canada (880), and China (737). However, there was an underreporting of disease for

developing countries. The information shows a clear bias to countries with more media outlets,

moredevelopedpublichealthresourcesandgreateravailabilityofelectroniccommunication(Major,

2008). Major (2008) reports that the research group at HealthMap is now developing ways to

improvecoverageforAfricaandSouthAmerica,whichhavethehighestriskandburdenofemerging

infectiousdiseases.Theprojectintendstomonitorotherinternetsources,suchasblogs,discussion

sites,andlistservstoincreaseitscapacitytocapturemorediseasesandalsoextendsitscoverage.

Asecond sourceofdatawas theAfricanUnion InterafricanBureauofAnimalResource (AUIBAR)

Animal Resource Information System (ARIS), which has recently been upgraded to capture and

transfer animal disease data in real time (AUIBAR, 2010). This information is sourced from the

monthly reportsof thenationalveterinaryservicesofAUmemberstates.Thenumberofnational

monthlyreportshasincreasedfrom10 in2000to47in2009andthequalityofspatialinformation

hasalsoimprovedwiththeuseofGPS(AUIBAR,2010).Weextractedadatasetofanthraxoutbreaks

recorded in2009 toexaminehow thegeocodeddata couldbemodelled inaglobal information

system(GIS)platform.Itwasnotspecifiedwhichspeciesof livestockorwildlifewereaffected.We

conducted an explanatory analysis to explore the association between the spatialdistribution of

anthrax and human population density, land cover, and species richness of wildlife (mammals,

ungulates,primatesandcarnivores).ThelandcovermapwasderivedfromtheGLC2000(Fritzetal.,

2004), thehumanpopulationdensity from the ILRIGISdatabaseand thewildlife species richness

fromtheAfricanMammalianDatabank(Boitanietal.,1999).Themammalianspeciesrichnesswas

derivedasaproxyforwildlifehostspeciesrichness(Jonesetal.,2008).Thespeciesrichnessmaps

weregeneratedfromgeographicalrangedistributionmapsforterrestrialmammalianspeciesfound

inAfrica(Boitanietal.,1999).Speciesrichnesswascalculatedasthenumberofspecies inanarea.

Wealsogeneratedspeciesrichnessmapsforungulates,carnivoresandprimatesandrelatedthem

toanthraxoutbreaks.


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Systematicreview

Thesystematicreviewwasthemainpartofthestudyandfollowedastandardapproach,comprising

thefollowingactivities:

Thematic areas within the scope of the TOR were identified, and team members wereassignedtodifferentthemes

Asetofsearchcriteriawasdevelopedforeachtheme relevantliteraturedatabaseswereidentified Asearchforpaperswasconductedforeachtheme Thepaper titleswere screenedby research assistants for relevance to the themeand the

abstractswereobtainedforsuitablepapers

Theabstractswereblindreviewedforrelevancetothethem byatleasttwoteammembersandabstractsselectedbytwoormorepeoplewereretained

Fullpaperswereretrievedfortheselectedabstractsandreadbyatleastoneteammember:thequalityofeachpaperwasevaluatedandthe keyfindingsfromeachpaperwasrecorded

usingastandardtemplate

For each theme, the findings from the selected paperswere collated andpresented as achapterinthisreport

Seventhemeswereidentifiedbytheteamandteammemberswereassignedtoeachthemebased

ontheirexpertise:

Disease transmission routes and relative importanceof the livestockwildlife route (leaderSilviaAlonsosupportedbyDeliaGraceandothers).

Pathogensofwildlifecapableofrecombiningwithanalogousorganismsindomesticlivestock(leaderRichardKocksupportedbyDeclanMcKeeverandothers).

Risk factors for disease transmission from wild/domestic animals to people and betweenwildlifeanddomesticlivestock(leaderDeliaGracesupportedbySilviaAlonsoandothers).

Drivers influencing interactionbetweenwildlife/livestockand the implications forzoonosestransmission(leadersDirkPfeiffer,BryonyJonessupportedbyRichardKock,MohammedSaid

andothers).

Historicalchangesintransmission,factorswhichfosternoveltransmissionroutesandhosts,and wild animal candidates for future disease transmission (leaders Dirk Pfeiffer, Bryony

JonessupportedbyRichardKockandothers).

Productionandsocioeconomicfactors influencingtheriskoftransmissionbetweenwildlifeand domestic livestock and from wildlife/livestock to people (leader Jonathan Rushton

supportedbyRichardKock,JemimahNjuki,MohamedSaidandothers).

Riskmanagement and control interventions and their successor failurewith emphasisoninterventions based on managing interaction between hosts (wildlife/livestock/humans)

(leaderDeliaGracesupportedbySilviaAlonsoandothers).

To identify papers relevant to each theme, the team generated a list of search criteria for each

theme.Twoformsofsearchesweredone,generalanddiseasespecific,forpaperspublishedinthe

past5yearsusingPUBMEDandCABDIRECTdatabases(AfricanJournalOnlinewasusedinitiallybut

waslaterabandonedbecauseityieldedveryfewhits).Fordiseasespecificsearches,teammembers

identifiedimportantzoonosesrelatedtoeachthemeandthediseasenamewasaddedtothesearch


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14

termsusedforthegeneralsearchesEveryeffortwasmadetoobtainthepapersthatwereselected

forfullpaperreview,althoughthiswasnotpossibleineverycase.

The paper reviewers assessed the strengthof evidence for each paper basedon the following

criteria: credibility of researchers; adequacy of study design (original studies); thoroughness of

review(reviewpapers);possiblebias;populationscovered;overall importance.Systematicreviews

usually involve setting strict criteria on quality of evidence to screen for highly credible original

studies; however, in this reviewwhen strict criteriawere applied insufficientor no studieswere

obtained. Using less strict criteria, review articles and discussion papers were included, and

additionalpapersobtainedfromreference listsofselectedpapersorknowntotheteammembers

butnotobtainedthroughthesystematicsearchwerealsoobtained. Thislargeandfuzzy literature

onthereviewtopic,meantwritersreliedextensivelyontheirownknowledgeandexpertise.

Table2.1.SummaryofpapersreviewedduringthesystematicreviewTheme No. papers

selected asrelevantbased ontitle

No. papers

selectedbased onabstractreview

No. papers

that wererelevantbasedon fulltextreview

Number of

additionalpapersused

Total number

of paperscontributingto themechapter

Disease transmission routes andrelative importance of thewildlifelivestockroute

98 28(ofwhich8

originalstudies)

11 5 16

Pathogens of wildlife capable ofrecombining with analogousorganismsinlivestock

171 30 30 36 66(ofwhich45

originalstudies)

Risk factors for diseasetransmission from wild/domesticanimals to people and betweenwildlifeandlivestock

153 13 4 8 12

Drivers influencing interactionbetween wildlife and livestockandtheimplicationsforzoonosestransmission

124 30 15 27 42(ofwhich19original

studies)

Historical changes intransmission,factorswhichfosternovel transmission routes andhosts,andwildanimalcandidates

for

future

disease

transmission

182 86 43 37 80(28original

studies)

Production and socioeconomicfactors influencing risk oftransmission between wildlifeand livestock and fromwildlife/livestocktopeople

? 33

Risk management and controlinterventionsandtheirsuccessorfailure with emphasis oninterventionsbasedonmanaginginteractionsbetweenhosts.

94 24 22 7 29

Total number of papers (some

papers were relevant to morethanonechapter)

239


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15

3. Importanceofzoonosesandthelivestockwildlifeinterface

Thefirstpartofthispaperdiscussessomeoftheconceptsaroundunderstandingzoonosesandwhat

ismeantby a livestockwildlife interface;wegoon to summariseevidenceon the importanceof

zoonoses(withreferencetothe livestockwildlife interface) intermsofhumanhealth impactsand

othersocietalconcerns;thethirdpartpresentsasystematicapproachtoidentifyingandprioritising

zoonoseswitha livestockwildlife interfaceofrelevance todevelopingcountriesanddiscussesthe

characteristicsofthesediseases.

Summaryofmainmessages

There isnoclearconsensusordefinitionofwhatconstituteszoonosesatthe livestockwildlifeinterface. Inthissystematicreview,werefertozoonoses,ordiseasescommontoanimalsand

humans, the epidemiology of which involves domesticated and nondomesticated animals

(includingfish).

In lowincome countries, infectiousdiseases are responsible fornearly 40%of theburdenofhumansicknessanddeath.Onefifthofthis(or8%ofthetotaldiseaseburden)isattributableto

zoonoses or diseases recently emerged from animals (7% and 13% respectively). Evidence:

medium.

In highincome countries, infectious diseases are much less important (4% of total burden);diseasesemergingrecentlyfromanimalsandfoodbornezoonosesareanimportantpartofthis

smallburden,butotherzoonoseshaveminorimpacts.Evidence:strong.

Zoonoses are absolutely and relativelymore important in lowincome countries compared tohighincomecountries.Evidence:strong.

Aswellashumanhealthimpacts,zoonoseswithalivestockwildlifeinterfaceareresponsibleformultipleburdens including:costof illness;costto livestocksector;costtoeconomies;negative

social andpsychological impacts; andnegative impactsonwildlife andecosystems.Evidence:

strong.

TheGlobalBurdenofDiseaseassessment ledbytheWorldHealthOrganisationsuggestsfoodborne zoonoses, human African trypanosomosis and leishmaniasis to be the most important

zoonosesglobally;allhavealivestockwildlifeinterface. Evidence:medium.

Publishedexpertopinionconsidersbrucellosis,humanAfricantrypanosomosisandtuberculosistobethemostimportantzoonoses;allhavealivestockwildlifeinterface.Evidence:weak.

Weidentified292importantzoonosesfromtheliterature:82%ofthesehadawildlifereservoir,74% had a domestic animal reservoir and 60% had both a wildlife and a domestic animalreservoir.Evidence:medium.

3.1Whatarezoonosesandwhatisalivestockwildlifeinterface?

Zoonoses are usually defined as diseases and infections that are naturally transmitted between

vertebrateanimalsandpeople(WHO,1959).Alandmarkpapershowedthatthemajorityofhuman

diseases (61%)aresharedwithanimals (Tayloretal.,2001).However, thissummarystatisticgoes

onlypartwaytounderstandingdiseasesatthe interfaceofhumans,animalsandtheenvironment.

Thedifficultyofattributionmakesitdifficulttounambiguouslydescribediseasesaszoonosesatthe

livestockwildlifeinterface:manydiseaseshavemultiplecauses,someofwhicharezoonoses;many

pathogenshavemultipletransmissionpathways(someofwhicharezoonoses)andinmostcasesthe


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16

relative importance of zoonotic pathways is not known; some diseases that are classified as

zoonosesareprobablybetterthoughtofascommunicablediseasescommontoanimalsandpeople;

and the categoriesof livestockandwildlifeareartificialandnotalwayshelpful.Moreover,hosts,

pathogens and transmission paths are not fixed but are constantly evolving. Lastly, the disease

centricmodelofpathogenandhostwhichhas longdominatedmedicalthinking, isgivingwaytoa

perspective that includes health issues at infrapathogen scale (transmission of drug resistance

betweenbacteriabyplasmids)andsuprahostscale(ecosystemservicesforhealthprovision).Some

of these issues are discussed in greater depth in Box 3.1. The commonly encounteredmodel of

wildlifeasreservoirsofdiseaseonlycapturessomeofthecomplexityofinteractionsatthelivestock

wildlifeinterface.Table3.2givesatypologyofzoonosesatthewildlifelivestockinterface.

Forthepurposesofthissystematicreview,zoonosesatthe livestockwildlife interface,aredefined

as: diseases that are common to animals and humans, the epidemiology of which involves

domesticatedandnondomesticatedanimals.

Box3.1Conceptualissuesaroundidentifyingzoonosesatthelivestockwildlifeinterface

Attribution:Diseasesmaybecausedbymultiplepathogens,someofwhicharezoonotic

Tuberculosisisoneofthemostseriousdiseasesofpeople.ThemajorityofcasesareduetoMycobacteriumtuberculosis, transmitted almost entirely by humantohuman transmission. (M. tuberculosis is a reversezoonosesandtherearedocumentedcasesofanimalsbeinginfectedbypeople,butthisisunlikelytoplayanimportantroleintransmission.)However,aproportionofhumantuberculosiscasesarecausedbyM.bovisthe cause of cattle tuberculosis. In developed countries where cattle tuberculosis is well controlled thisproportion isvery low (around0.11%ofcases),butbeforemilkpasteurizationM.boviswasan importantcauseofhumantuberculosis,especiallyintestinaltuberculosisinchildren.Therearefewstudiesofzoonotic

tuberculosis in developing countries and poor communities; those that exist have shown proportions ofhumantuberculosisduetoM.bovisofupto45%insomepopulations(Rodwelletal.,2008),althoughfrom520%ismoretypical(Cosivietal.,1998).

Table3.1.Humandiseasescausedbymultiplepathogens

Examplesofzoonoticspecies

Examplesofnonzoonoticspecies

Proportionofdiseaseduetozoonoticpathogens

Tuberculosis Mycobacteriumbovis M.tuberculosis 10%(20%)

Leishmaniasis Lmajor;mostotherspecies

L.tropica;Ldonvani Unclear,perhaps75%

Lymphaticfiliariasis Bmalayi,Btimori Wuchereriabancrofti 10%

Shistosomiasis S.japonicum S.mansoni,S.

haematobium

10%

Malaria P.knowlesiandothers P.falciparum andothers

Very small

Attribution:Pathogensmayhavemultipletransmissioncyclessomeofwhicharezoonoticandothersnot

Manyarboviruseshaveasylvaticcycle,whilstsomealsohaveanurbancycleandanintermediatecycle.

Sylvaticcycle(sometimesknownasthejunglecycle):theviruscyclesbetweenanarthropodandanonhuman mammalian host. Humans are usually deadend hosts that are infected by thearthropod.

Intermediate cycle: occurring in agroecosystems with both human and nonhuman mammalianhosts.

Urbancycle:theviruscyclesbetweenhumansandanarthropodspecies.In the case of dengue, a high burden disease, almost all transmission is urban (human to human or


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17

anthroponotic)andmanypeoplewouldnotconsiderittobeazoonoses.However,theexistenceofasylvaticcyclemeansthatitisbydefinitionazoonoses,andmayhaveimplicationsforpersistenceandresurgenceofdisease,asdiseaseswithasylvaticcyclearemoredifficulttocontrol.

Many diseases are transmissible through different sets of hosts. For example, dairy cattle are a majorreservoir for Escherichia coli O257:H7, but once a person is infected (typically through milk, meat or

vegetables contaminatedwith cattle faeces) thenpersontoperson transmission is also possible. There isgenerallylittleinformationontheimportanceofdifferenttransmissionroutes,whichmakescontroldifficult.

Attribution:Commonsourcecommunicablediseases

Zoonosesareoften conceptualised in termsofdiseaseswith reservoirsof infections inanimals.Formanyzoonoses,thereservoiristheenvironmentandhumans,wildlifeandlivestockmayallbeaffected.Thesearesometimes referred to as communicable diseases common to humans and animals and are not alwaysconsideredaszoonoses.Tetanussporesarepresentubiquitouslyintheenvironmentaswellastheintestinesofanimalsandhumans.Whilehuman infectionfromananimalbite ispossible,orfromapplicationofcowdungtotheumbilicus,muchofthehighburdenofhumantetanusisfromtheenvironmentandnotdirectlyfromanimals.

Attribution:Arbitrary

distinction

between

livestock

and

wildlife

There are many different classifications of the animals with which humans share ecosystems. Livestock,domesticanimals,peridomesticanimals, foodanimals,workanimals,companionanimals, feral,pest,andwildlifeoverlapand varyby context.Dependingon the contextdogsmaybe foodanimals,workanimals(guarddogs),companions,orferal. Nichelivestocksuchasguineapigs,rabbits,pigeonsandgiantsnailsareimportant insomeareasandoftenharbourspecificdiseasesandzoonoses.Wildlifeare increasinglybeingdomesticated (deer,elk)ormanaged. In some contexts feral livestock (pigs, camels,goats)occupy similarnichestowildlife.

Transmissionpathwaysarenotstaticbutshiftaccordingtoevolutionarypressure

Ashift fromwildlifetowildlife, towildlifetodomesticanimal, todomesticanimaltohuman (zoonotic), tohumantohuman(anthroponotictransmission)wouldbeanexpectedevolutionaryresponseofpathogensto

increased transmission opportunities. Numerous investigators believe that visceral leishmaniasis wasoriginally an infection that circulated among wild animals (canids and perhaps rodents), and that later,domesticdogswere included in itscycle;eventually,thediseasebecamean infectiontransmittedbetweenhumanswithoutthe interventionofananimalreservoir,as isthecaseofkalaazar in India.This isalsothepatternforhumaninfluenzapandemics.Influenzavirusescirculateinwildbirds,somevirusesthenevolvetobeabletoaffectdomesticbirdsandpigs,thentovirusesthatoccasionallyaffectpeople,andthentovirusesthatarehighlycontagiousbetweenpeople.

Animalsconditioningagroecosystemsinwaysthatfosterorreducedisease

Animals may alter ecosystems in ways that increase and decrease the risk of disease in people. Someexamplesare: histoplasmosis,adiseaseofhumans,dogs,cats,cattle,sheep,horses,andmanywildmammals.Thefungus

causingthediseasegrows insoilenrichedwithavianorbatfaeces;birdsthemselvesarenotsusceptibletothedisease,buttheirfaecesplayacentralroleincreatingareservoirforthedisease. Clostridiumtetaniisanormalinhabitantoftheintestinesofhorsesanddomesticruminantsandruminantfaecescontributestocontaminationofsoilwithtetanusspores,especiallywhereanimalmanure isusedasfertiliser. C.difficile,a common causeof infectiousdiarrhoea inhospitalisedhumans, ispartof themicrofaunaofdomesticanimals.Useofcephalosporinsinanimalsisincreasingtheriskofresistantstrainsenteringthefoodchainandenvironment,potentiallyleadingtoanincreaseofcasesinthecommunityratherthanthecurrentnosocomialincidence. HPAIH5N1 isassociatedwithspecificagroecologicalconditionsthatarepresent inSouthEastAsia,Chinaand Egypt. The role of backyard poultry and domestic ducks in wetland systems contributing to thepersistenceofinfectionandwildbirdreservoirsissuggestedfromavailableliterature,butequivalentstudyofthecontributionof intensivepoultryproductionsystemshasbeenresistedbythe industryandwidespreadvaccinationhasreducedsurveillanceandepidemiologicalinvestigation.


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Table3.2Differentepidemiologicalpatternsforzoonoseswithalivestockwildlifeinterface

Patterns Definition Example

People

in

the

parasite

developmentcycles Humans

are

final,

intermediate

or

aberranthostsfordiseaseswithmultihostlifecycles Humans

are

final

host

and

aberranthostsforpigtapeworm

Wildlifereservoirforlivestockandhumaninfection

Infectioncirculatesinwildlifemakingeradicationfromlivestockdifficultandhenceposingrisktohumans

Brucellosisinbison;tuberculosisinbadgers

Diseasesinecosystems Diseasesexistinsylvatic(wildlifeonly),domestic(domesticanimals)orurban(humanonly)cycles,specifictoecosystems,thatmayconnect

dengue(sylvaticandurban);trichinella

Communicablediseases

commontohumansandanimals

Livestock,wildlifeandhumansare

susceptibletoadiseasethatiscommonintheenvironmentbutanimalsarenotinvolvedintransmissiontohumans

Manyfungaldiseases

Animalsastransportersfacilitatingpathogenspread

Animalsallowspreadofdiseasebytransportingpathogensinfleasorticks

Dogsandanimalstransportfleaswithbubonicplague

Animalsconditioningecosystemstobettersupportpathogens

Wildlifeorlivestockcontaminateenvironmentwithpathogensorcreateconditionsthatfosterpathogengrowth

Ruminantgutsandfaecesarereservoirsforanthraxandbotulism

Pigeonandbatfaecesarereservoirsforhistoplasmosis

Agricultureasariskfactorforzoonoses

Agricultureincreasesriskbyprovidinghostsorenvironmentalconditionsforpathogens

Foodbornezoonoses

EmergingpathogenssuchasC.difficileandavianinfluenza

Reversezoonoses Wildlifeordomesticanimalsareatriskfromhumandiseasesbutdonotplayaroleintransmissionorspread

Humantuberculosisindogs

Measlesinmonkeys

4.2Importanceofzoonosesatthelivestockwildlifeinterface

4.2.1Importancetohumanhealth

4.2.1.1ContributiontoGlobalHealthBurden

TheunitofDisabilityAdjustedLiveYear(DALY)hasrevolutionisedassessmentandprioritisationof

humanhealthburden (Mathersetal.,2002). Introducedby theGlobalBurdenofDiseasestudy in

theearly1990s,DALYsarethepresentvalueoffutureyears lostduetoprematuredeathorbeing

alive with poor health. The Global Burden of Disease (GBD) provides a comprehensive and

comparableassessmentofmortalityand lossofhealthdue toover150diseases, injuriesand risk

factors forallregionsof theworld.Of33diseases listed inthesectioncovering infectiousdisease


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19

and respiratory infections,onethirdarezoonosesorhaveazoonoticcomponent,andallofthese

haveawildlifeinterface.

TherearethreeproblemswithusingtheGBDtoassesstheimportanceofzoonoses.Firstly,several

zoonoseswithconsiderableburdensarenotincludedintheGBDassessment.Forexamplerabiesis

estimated to cost 1.7millionDALYsper year inAfrica andAsia alonebut isnot considered as a

nameddiseaseor illness(Maudlinetal.,2009).Other importantzoonoseswithawildlife interface

and largeburdens thatarenot includedare cysticechinococcosis, cysticercosis, leptospirosisand

brucellosis. Secondly, zoonoses (especially in poor countries) are systematically underreported

relativetootherdiseases(Schellingetal.,2007,Maudlinetal.,2009)and,astheGBDreportisbased

onnationalinformationonlevelsofmortalityandcause,thisbiasisreflectedintheGBD.Thethird

problemisoneofattribution.TheGBDis,asthenamesuggests,organisedarounddiseasesandnot

pathogensortransmissionpathways. Forexample,diarrhoealdiseases,amongstthehighestcauses

of morbidity and mortality in poor countries, comprise one category. Although the majority of

important diarrhoeal pathogens are zoonotic (Schlundt et al., 2004) and many of these have awildlifeinterface,itisnotcurrentlypossibletoidentifythezoonoticcomponentfromGBDfigures.A

promisinginitiativeisunderwaytoattributefoodbornediseasetopathogenlevel(Kuchenmlleret

al.,2009)whichwillassistinbetterunderstandingofthezoonoticburden.

Despitethesecaveats,DALYsrepresentauniversallyagreedwayofassessingtheburdenofdisease

tohumanhealthandalogicalapproachtoatleastroughlyestimatingthehealthburdenofzoonoses

at the livestockwildlife interface.We apply this to the assessmentof zoonoseswith a livestock

wildlifeinterfaceinTable3.3(detailsofthecalculationsareprovidedinAnnex1).

Table3.3

Burden

of

zoonoses

in

terms

of

death

and

disability

Highincome countries Lowincomecountries

TotalDALY %Total TotalDALY %Total

Allcausesofsicknessanddeath 122,092,000 100% 827,668,844 100%

Infectiousandrespiratorycauses 4,128,000 3.4% 319,905,538 38.7%

Zoonosesanddiseasesrecentlyemergedfrom

animals

768,770 0.6% 64,951,636 7.8%

Diseasesrecentlyemergedfromanimals 631,600 0.5% 44,727,571 5.4%

Zoonoses 140,770 0.12% 22,084,983 2.7%

Zoonoticfoodbornedisease 131,400 0.11% 17,762,144 2.1%

Themost important zoonoses in lowincome countries inorderofdecliningburden are: zoonotic

foodborne disease, human African trypanosomosis, zoonotic leishmaniasis, zoonotic lymphatic

filiariasis,Japaneseencephalitis,zoonoticschistosomiasisandzoonotictuberculosis.


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20

Inhighincomecountries,zoonosesanddiseasesrecentlyemergedfromanimalsconstitute18.6%of

theburdenof infectious and respiratorydiseasebutonly 0.6%of the totalburden:mostof this

burden is due to HIV/AIDS. Zoonoses make upjust 3.4% of the total burden of infectious and

respiratorydiseaseandnearlyallofthisisduetozoonoticfoodbornedisease.

Inlowincomecountries,thetotaldiseaseburdenismuchhigherthaninhighincomecountriesand

theshareof infectiousandrespiratorydiseasesmorethan tenfoldhigher.Zoonosesanddiseases

recentlyemerged fromanimalsconstitute20.3%of the infectiousandrespiratorydiseaseburden;

zoonoses are relatively more important than in highincome countries, making up 6.9% of the

infectiousandrespiratorydiseaseburdenwhereasinhighincomecountriestheyconstitute3.4%of

the infectious and respiratory disease burden. Moreover, while the proportion of infectious and

respiratory disease is 13 times higher in lowincome countries than highincome countries, the

proportion of zoonoses is 23 times higher. This supports the common perception that zoonotic

diseasesarerelativelymoreimportantinlowincomecountries.

3.2.1.2Expertopinion

Theonlysystematicglobalprioritisationofzoonoseswithapropoor,developmentperspectivewas

carriedoutbyILRIin2002(Perryetal.,2002).Inthisstudy,brucellosis,whichisnotincludedinthe

GBD,was considered tobeby far themost important zoonosis, followedby trypanosomosis and

tuberculosis(Figure3.1).

Diseaseswererankedinorderofthosewiththegreatestimportancetothelivelihoodsofthepoorin

eachlivestockproductionsystemintheirregion.Thediseaseswerethenrankedbytheidentification

and quantification of their impacts on the poor. Then, three major impacts of each disease or

syndrome were identified and scored. These were socioeconomic impacts (primarily production

lossesandcontrolcostsincurredbythepoor),zoonoticimpactsandnationalimpacts(acombination

ofmarketing impactson thepoorwithpublicsectorexpenditureondiseasecontrol).Aweighting

wasapplied to thescores foreachdisease relating to the importanceofdifferent impactson the

poor(forexample,socioeconomicimpactwasgivenaweightingof85%andnationalimpact,15%).

Zoonoticdiseaseswererankedseparatelyduetothedifficultyofmeasuringthemonetaryvalueof

humanhealthimpacts.

Sixdifferentsetsofrankingsofanimaldiseasesbyexpertsandfarmers,withoutaspecificfocuson

zoonoses,aresummarised inPerryandGrace(PerryandGrace,2009).Theauthorsnoteastriking

lack of consensus between the lists; however, brucellosis, tuberculosis and human African

trypanosomosisappearonseverallists.

Wefoundonlyonesystematiccomparativestudyofthedirectcostsofanimaldiseasesatnational

level (GreatBritain) (Bennettand Ijpelaar,2005).Partof thestudy lookedat thecostsandhealth

impactsoftenzoonoses;enterotoxigenicE.coli,salmonellosis,fascioliasis, leptospirosis(L.hardjo),

pasteurellosis, salmonellosis and tuberculosis in cattle; psittacosis (enzootic abortion), orf and

toxoplasmosisinsheep;StreptococcussuisTypeIImeningitisinswine;andsalmonellosisinpoultry.

Salmonellosisrelatedtopoultryhadbyfarthehighesthumanhealthcoststogetherwiththehighest

humanwelfare impactscore.ThiswasfollowedbysalmonellosisrelatedtocattleandE.coliO157


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oticdiseas

andbetter

inscientific

yresearch

individual

llows us t

ountrieswi

noticdiseas

logy). Our

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reflectan

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portant zo

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important (

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thanwildlif

literature.

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iseases(an

globally as

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study, like

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ereunkno

followedb

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nosis) and

we found

Cleaveland

inotherstu

nallzoonot

e,whichwo

someare

sess and c

livestockin

iningandsc

others, did

s of the

ingcountri

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fe,74%ha

e causedb

nour

datab

ed; 51% w

2%were ro

norpoten

primates.

1)andCle

used patho

carnivores

tal.,2001,

ies,whichi

icpathogen

uldresultin

cited inCha

mpare the

terface

reeningan

not show

umber of

s,75%ind

evelopedc

countries.

livestock r

helminths,

aseof

292

i

re domesti

dents.Wild

tially includ

velandeta

gens as th

and ungulat

Tayloreta

sprobablyt

s.However,

overrepre

22

pter11),

costs of

mberof

a major

oonoses

veloped

ountries,

e found

servoirs

25%by

portant

(cattle,

animals

edboth.

l.(2001),

unit of

es to be

l.,2001).

heresult

livestock

entation


23/128

23

Experts identified61diseasesatthe livestockwildlife interface indevelopingcountriesconsidered

importantbecauseofactualorpotentialnegativeimpactsonpeople,domesticanimals,wildlifeand

ecosystems.Whilemost were confirmed zoonoses, somewere considered important because of

possible or potential (though not proven) zoonotic transmission or because understanding the

disease had implications for zoonoses at the livestockwildlife interface. Among these diseases,

virusespredominated as the causative agent, followedbybacteria thenprotozoa andhelminths.

Nearlyhalfofthesediseaseshadmultipletransmissionroutes(39%).Amongstthosewithonlyone

transmission route,16werevectorborne,11were transmittedbydirectexposure,8were food

borneandonewastransmittedbyaerosol.

Table3.4Importantzoonosesatthelivestockwildlifeinterfaceindevelopingcountries

DiseaseName CausativeAgent Typeofagent

Acariasis(mange)Sarcoptesspp,Cheyletiellaspp,Dermanyssusspp,Ornithonyssusspp

Arthropod

Myiasis Hypodermabovis Arthropod

Anthrax Bacillusanthracis Bacteria

Botulism Clostridiumbotulinum Bacteria

Bovinetuberculosis Mycobacteriumbovis Bacteria

Brucellosis Brucellaabortus Bacteria

Campylobacterenteritis Campylobacterjejuni,C.coli Bacteria

Haemolyticuraemicsyndrome Escherichiacoli(0157:H7) Bacteria

JohnesDisease Mycobacteriumaviumsubspppseudotuberculosis Bacteria

Leptospirosis Leptospirainterrogans Bacteria

Lymedisease Borreliaburgdorferi Bacteria

Plague Yersiniapestis Bacteria

Relapsingfever Borreliarecurrentis Bacteria

Salmonellosis Salmonellaeenterica Bacteria

Tuberculosis Mycobacteriumtuberculosis Bacteria

Tularemia Francisellatularensissubspturalensis Bacteria

Actinomycosis Actinomycesisraelii Fungal

Cryptococcosis Cryptococcusneoformans Fungal

Clonorchiasis Clonorchissinensis(Chineseliverfluke) Helminth

CutaneouslarvamigransAncylostomabraziliense,A.caninum,Uncinariastenocephala

Helminth

Alveolarechinococcosis Echinococcusmultilocularis Helminth


24/128

24

Cysticechinococcosis Echinococcusgranulosus Helminth

Fascioliasis Fasciolagigantica Helminth

Schistosomiasisjaponica Schistosomajaponicum Helminth

Intestinalschistosomiasis Schistosomamansoni Helminth

Trichinellosis Trichinellaspiralis Helminth

Amebiasis Entamoebahistolytica Protozoa

BabesiosisBabesiacanis,B.microti,B.divergens,B.bovis,B.equi

Protozoa

Cryptosporidiosis Cryptosporidiumparvum Protozoa

Giardiasis Giardialamblia Protozoa

Leishmaniasis Leishmaniadonovani,otherspp Protozoa

Malariaofnonhumanprimates Atleast20speciesofPlasmodium Protozoa

Toxoplasmosis Toxoplasmagondii Protozoa

Trypanosomiasis(Africansleepingsickness)

Trypanosomabrucei,T.bruceirhodesiense, T.bruceigambiense

Protozoa

Anaplasmosis Anaplasmaphagocytophilum Rickettsia

Qfever(Queryfever) Coxiellaburnetii Rickettsia

Chikungunya Alphavirus Virus

Cowpox Cowpoxvirus Virus

CrimeanCongoHaemorrhagicFever Nairovirus Virus

Denguefever Denguefevervirus Virus

Ebolahaemorrhagicfever Ebolaviruses Virus

FootandmouthdiseaseFootandmouthdiseasevirus(aphthovirustypesA,O,C,SAT1,SAT2,SAT3andAsia)

Virus

Hantaviral

diseases

Hanta

virus

Virus

Hemorrhagicfeverwithrenalsyndrome

Hantaanvirus,Dobravavirus,Puumalavirus,Seoulvirus

Virus

Hendravirusinfection Hendravirus(paramyxovirus) Virus

HepatitisE HepatitisE virus Virus

InfluenzatypeA(swine/avian/Hong Kongflu)

Influenzavirus(myxovirus) Virus

JapaneseBencephalitis Japaneseencephalitisvirus(flavivirus) Virus

Lassafever Lassavirus(arenavirus) Virus


25/128

25

MarburgHF Filovirus Virus

Monkeypox Flavivirus Virus

Newcastledisease Newcastlediseasevirus(paramyxovirus) Virus

Nipahvirusinfection Nipahvirus Virus

Orf(contagiousecthyma) Poxvirus Virus

Rabies Rhabdovirus Virus

RiftValleyfever Phlebovirus Virus

Rotavirus Rotavirus Virus

Severeacuterespiratorysyndrome(SARS)

Coronavirus Virus

Tickborneencephalitis Flavivirus Virus

WestNilefever WestNilevirus(Flavivirus) Virus

Yellowfever Flavivirus Virus

Ourexpertbaseddiseaseselectionbroadlysupportstheliteraturecitedinconfirmingthe

importanceofvirusesandmultihostpathogensasmostproblematicagentsandbats,carnivores

anddomesticherbivoresasmostproblematichosts.


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26

4. Mappingzoonosesatthelivestockwildlifeinterface

Introduction

Epidemiologists have traditionally used maps when analyzing associations between locations,

environmentanddiseases(Clarkeetal.,1996).Ostfeldetal.,(2005)pointsoutthatmapshavebeen

used for two distinct purposes in epidemiology. The first involves retrospective analyses of

spatiotemporallydynamicepidemicstounderstandwhatfactorsgovernthespatialpatternandrate

of spread of diseases. The second major use of maps in epidemiology is to characterize spatial

variation in contemporaneous (static) ecological risk of infection and potential causes of that

variationandthatspatialdataondiseaseincidencecanbeusedtoextrapolatetheriskofexposure

from currentdistributions tonew geographical areas.The ability tomakemaps interactivelyhas

increased thepotential formanyusers touse the information.Coupledwith increasinganalytical

functionalityofGeographical InformationSystem (GIS) that ranges fromvisual toexploratoryand

modelling, the uses of GIS in epidemiology has increased significantly (Pfeiffer and HughJones,2002,Ostfeldetal.,2005).

The output generated by GIS in map format has the particular advantage of showing implicit

representation of spatial dependence relationships in an intuitive manner. The technology is

becoming an essential component of modern diseases surveillance systems (Pfeiffer and Hugh

Jones,2002,Jonesetal.,2008).Theopportunitiesforepidemiological investigationhave increased

withwebbasedmappingtools,useofGlobalPositioningSystem(GPS)inmappingdiseaseoutbreaks

andincreasedprecisionandfrequencyofcollectingtheinformation.

Results

UsingHealthMapdata,Figure4.1ashowsthespatialdistributionof15zoonoticdiseasesorgroups

ofdiseases inrelationtohumanpopulationdensity.Theoutbreaksoccurred inboth lowandhigh

humanpopulationdensityareas (Figure4.1b).Majorcitieshadoutbreaksofzoonoticdisease.The

highdensity reported cases includedCairo andAlGiza in Egyptwhere avian influenzaoutbreaks

werereported,andinWestAfricaavianinfluenzawasreportedinKano.Alsofoodborneillnesswas

reported in Safaga and El Manial in Egypt. These areas have population densities of more than

10,000peopleperkm2.Examplesofotherbigtownswithpopulationdensititiesoflessthan10,000

people per km2 that reported outbreaks of disease included Kampala (outbreaks of dysentery,

diarrhoeaandbotulism),andCocody,Abidjan(outbreakofavianinfluenza).

This type of spatial analysis provides us with potential information on risks of diseases to a

population.Asthesediseasedatabasesbecomemorepopulatedwithinformation,itwillstrengthen

thebasisformodellingandalsoprovideinsightsonwhattypeofthreatsthesediseasescanhaveon

humanpopulations.

Thenext stepof theanalysiswas toderiveahotspotmapon the15 zoonoticdiseases,which is

shown in Figure4.1c.. As indicated inthemapthehotspotswere located inEgyptalongtheNile,

centralandwesternKenya,centralUganda,Zimbabwe,andnorthwesternSouthAfrica.Theanalysisindicates that West Africa is also an area with a high number of zoonotic disease reports. The


27/128

countri

suchas

areasof

thesedi

Figure

2006to

Thedo

Figure

sincludeNi

Morocco,Al

highzoono

seases,whi

.1aSpatial

April2011

srepresent

.1bDisease

geria,Togo,

geria,Ethio

icdiseaser

hisnotadd

appingof

outbreaks,

outbreaksi

1

Huma

0

100

200

300

400

Numberofd

isease

outbre

ak

s

Benin,Cote

ia,Namibia

ports.Anot

ressedinthi

15zoonotic

ithadiffer

relationto

10

population

dIvoire,Ga

,Angola,Za

herlevelof

sproject.

diseaseout

ntcolourf

humanpo

100 10

density (p

mbia,Guine

biaandM

analysisist

breaksinre

reachofth

ulationden

00 10000

rson per sq

aandSeneg

dagascarw

findoutw

ationtohu

15disease

sity,Jan20

km)

0.0

0.1

0.2 Prop

ortion

perBar

al.Inother

eobservep

atarethe

manpopula

types.

6toApril2

27

ountries

cketsof

riversof

tion,Jan

11


28/128

Figure

Thema

theare

Thedis

hotspot

Nigeria

anthrax

influenz

foodbo

Zimbab

anthrax

Thenex

gramp

andwil

al.,201

per cen

persons

perkm2

greatth

mostof

on the

occurre

toothe

.1cHotspot

wasderiv

ofthecircl

asesvaried

s. In Egypt

the outbre

. InSouthA

a.InZimba

rne illness

e. InKeny

andfoodb

tlevel

of

a

sitivesporu

lifespecies,

).Figure4.

t of the ou

perkm2). A

. Fifteenpe

an200pers

theoutbrea

relationship

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dense

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landcover.

ofzoonoti

dfromzoo

isproporti

across the

herewere

aks were g

rica itwas

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alysisfocu

latingbacte

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tbreaks we

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ksoccurred

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oticdiseas

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outbreakso

astroenterit

oodborne

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srecorded

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anth

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outbreaks

e reported

theoutbre

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innaturalv

nthrax out

ostlyin

wo

Africa.

soutbreaks

umberofdi

ndwe liste

f avian infl

is, foodbo

illness,dyse

tedweredi

ganda had

werediarr

raxusing

2anthracis,

spublichea

ofanthraxi

in low hu

kswereloc

ereportedi

cidenceina

getationth

breaks and

dlandsand

.Circlesrep

seasesinth

someofd

enza, food

ne illness,

ntery,diarr

arrhoea,dy

similar dis

oea,avian i

09AU

IBAR

whichprima

lthriskinm

relationto

an populat

atedinarea

nareaswhe

reasoflow

tislessinh

land cover

shrublands

esentone

cell.

seaseoutb

borne illnes

diarrhoea,

oea,Crypto

entery,ant

ease outbr

nfluenza,d

data.

Anth

rilyaffects

nypartsof

humanpop

ion density

ofbetwee

rethepopu

umanpopu

bitedbype

shows tha

Figure4.3a

egreegrid

eaks in so

s, anddyse

avian influ

sporidiuma

hrax,gastro

aks as rep

sentery,sal

raxis

cause

erbivorous

theworld(

ulationden

areas (less

50and20

lationdensi

lationdensi

ople.Spatia

outbreaks

and4.3b)

c

28

ells,and

eof the

ntery. In

nza and

ndavian

enteritis,

orted in

monella,

dby

the

livestock

emboet

ity.Fifty

than 50

persons

ieswere

tyisthat

lanalysis

in 2009

mpared


29/128

Figure

2009.

Figure

Studies

anthrax

Vanderj

than50

(Gates

Gatesa

.2a Spatial

.2bAnthra

inLakeMa

epidemicst

eugd,1993)

%ofmorali

tal.,

1995)

tal., (1995)

distributio

outbreaks

yara inTa

hatdrastica

.A studyo

ty inbison

.They

use

pointout t

Hu

0

50

100

150

N

umbero

fanthraxoutbreaks

of anthra

nrelationt

zania indica

llyreduced

a freeran

Bosbisonainfrared

c

atanthrax

0 100 200

an poulation

x outbreak

humanpo

te that shr

heimpalap

ingpopula

thabascae)

merason

bacteria fo

300 400 50

density (per

in relation

ulationde

bestablish

opulationin

ionofbiso

occurred in

oardhelico

mhighly re

600 700 8

on per sq k

to human

sity,2009.

ent in the

1961,1977

inCanada

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de

istantendo

0

)

0.0

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30/128

conditio

epidemi

areas (

periods

Figure

Figure

nsareright

cs.Densev

rinsandVa

followedby

.3aSpatial

.3bNumbe

maintaina

getationca

nderjeugd,

dryconditi

istribution

ofoutbrea

N

nthraxinth

nmaintaina

993,Gates

ns(Gateset

ofanthrax

sof

anthra

mberofant

environm

ndconcent

etal.,199

al.,1995).

utbreaksin

in2009

re

raxoutbreak

ntoutsidel

atetheses

)before th

2009inrel

ationto

lan

sin2009

ivinghostsf

oresforlo

yare trigg

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dcover

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gertimest

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between

anopen

gedwet


31/128

Figure

wascal

Figure

andcar

.4aSpatial

ulatedast

.4bOutbre

ivora.

2

4

6

8

100

120

Numberofanthraxoutb

reaks

5

100

150

Numberofanthraxoutb

reaks

istribution

enumbero

ksof

anthr

0 10 20 30

MAM

0 5

PRI

ofanthraxi

fspeciesin

axin

relatio

0 50 60 70

MALS

10 15

ATES

nrelationt

anarea.

nto

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00.0

0.1

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0.3

0.4

0.5

Proportion

perBar

0

10

20

30

40

50

60

70

Numberofanthraxo

utbreaks

00.0

0.1

0.2

0.3

0.4

0.5

0.6

Proportion

perBar

0

20

40

60

80

100

120

Numbero

fanthraxoutbreaks

mammals

richness

o

0 10

UNGU

5 10 15 2

CARNI

eciesrichn

mammals,

20 3

ATES

0 25 30 3

VORA

ss. Species

ungulates,

00.0

0.1

0.2

0.3

Proportion

perBar

50.0

0.1

0.2

0.3

0.4

0.5

Proportion

perBar

31

richness

rimates


32/128

32

Theoccurrenceofanthraxinrelationtomammalspeciesrichnessshowshighoccurrenceofanthrax

in high mammal rich areas (Figure 4.4a). Similar, patterns are exhibitedwith species richness of

ungulatesandcarnivora(Figure4.4b).However,theoutbreaksofanthraxoccurred inareasof low

species richness forprimates.Manyof theprimates are found in verydensewooded vegetation

whereanthraxoutbreaksmighthavebeendifficulttodetect.

Mostoftheanthraxoutbreakswereoutsideprotectedareas,butasindicatedinthemapthespecies

richnessofanimalsgoesbeyondtheparkandmanyoftheseanimalswillbeincontactwithlivestock

andpeople.Manyoftheseparksaresmall insizeandinmanycountriesweredryrangerefugefor

livestock.Aspeopleandlivestockincrease,therangeforwildlifeisbecomingsmallerandthecontact

between livestock andwildlife is increasingwhichwill increase transmissionofdiseasesbetween

wildlifeandlivestock.

Conclusions

Explanatoryspatialanalysiswiththedatasets(pointdata)showsthegreatpotentialincharacterizing

thespatialvariationofdiseasesinrelationtoanumberofenvironmental(landcover),social(human

population)andwildlife (species richness)variables.Thepotentialofspatialtemporalanalysishas

increaseddue to the resolutionofdata (georeferencingusing theGPS) in thatmanydiseasesare

mappedwheretheydidoccur.

Toolsdeveloped todealwith suchdatahave improved thedata integration, correlation analysis,

hypothesissettingandalsocommunicationofthe informationtothepublic.However,asmanyof

the organizations are just starting to develop geodatabases on diseases we still have under

reportingofdiseases. Jonesetal (2008)suggestthatthere isacriticalneed forhealthmonitoring

andidentificationofnew,potentiallyzoonoticpathogensinwildlifepopulations.Theyalsoadvocate

forreallocationofresourcesforsmartsurveillanceofemergingdiseasehotspotsinlowerlatitudes

suchastropicalAfrica,LatinAmericaandAsia.

The major hurdle in geospatial data on zoonotic diseases is data accessibility. Many of these

programsarejuststartingandmany institutionsfind itdifficulttosharedata. Itwillbehelpfulfor

these institutions todeveloppolicyandregulationsondataacquisitionanddatause.Globalscale

dataonenvironment(landcoverandvegetationindicesfromsatelliteimages),socioeconomicand

humandemographyarenowwidelyavailablecomparedto2030yearsago.Many institutionsare

making their data available through the internet and also through institutional agreements.

Improvementinthemodellingofdiseaseswillbepossiblewithaccessibilityandavailabilityofthese

datasets.

Lackofreliablegeoreferenceddataonzoonosesprevalenceorevenpresencehinderedmapping;

thiswaspartiallyovercomebycollaborationwithHealthMap.However,dueto limiteddata itwas

notpossible to carryoutdetailed investigationof the linksbetweengeoreferencedenvirosocio

economicgeoreferenceddataanddiseases,but in thenear future this is likely tobepossibleas

thesehealthdatabasesgatherandconsolidatetheinformationthatisscatteredinmanyplacesand

organizations.


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33

5. Diseasetransmissionroutesandtherelativeimportanceofthewildlife

livestockroute

Summaryofmainmessages

Human habitat expansion, for habitation or agriculture, has contributed to greater contactbetweenhumansandwildlifeand resulted in theemergenceofpreviouslyunknown zoonotic

diseasesfromwildlife.Evidence:high.

Livestock movements (seasonal or all year round) and wet markets provide importantmechanismsforzoonoticdiseasespread.Evidence:high.

Consumptionofbushmeatrepresentsoneofthemostobviouswaysinwhichhumanscomeintoclose contactwithwildlifeand theirpathogens. It isan important sourceof zoonoticdisease

transmissionfromwildlife.Evidence:medium.

Keepinglivestockmaypotentiallyincreasetheriskofzoonoticdiseasetransmissionfromwildlifetohumansbecause livestockmay create anew linkbetweenwildlife andhumans thatwere

otherwisenotconnected.Evidence:medium.

Introduction

Understanding thediverse transmission routesof infectiousdiseases fromwildlife tohumans isa

first step in the assessment of any potential risks associated with wildlife. A large number of

infectiouspathogensareknowntobeharbouredbywildanimals,andmanyhavetheabilitytojump

from wildlife to humans and livestock. Many different transmission routes exist for infectious

diseases ingeneral, includingdirecttransmission,airborne,vectorborneand indirecttransmission

via fomites (including food). In the case of zoonoses related to wildlife, there is still no clear

understandingofwhicharethemostimportanttransmissionmechanismsandwhetherprioritization

ispossibleasawaytoinformallocationofresources.Mostzoonoticpathogensfoundinwildlifeare

not exclusive to these animals but are also found in domestic animals. The degree of contact

betweenhumansanddomesticanimals is inmost cases greater thanwithwildlife.

r4d.dfid.gov.uk pdf outputs livestock 60877-dfid final25!9!2011

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