The impact of wildlife in the epidemiology of RVF

(1)

The Impact of

wildlife

_wildlife

in the

_{in the}

epidemiology

of RVF

UR AGIRs « Animal et Gestion Intégrée des Risques»

CIRAD – ES

(2)

Ruminant Ruminant Mosquitoes Mosquitoes Infected eggs Vector transmission Vertical transmission Direct transmission Wild reservoir ? Humans Introduction

Theorical epidemiological cycle of RVF

(3)

What

is

a

reservoir

?

ManyMany differentdifferent and and oftenoften contradictorycontradictory definitionsdefinitions

(

(HaydonHaydonet.al, EID, 2002)et.al, EID, 2002)

PathogenicPathogenic (WN and (WN and birdsbirds in US) / non in US) / non pathogenicpathogenic (WN and

(WN and birdsbirds in EU)in EU)

1 host (1 host (badgerbadger and M. and M. BovisBovis in UK) / multiin UK) / multi--host host system (dog+

system (dog+jackaljackal and and rabierabie in in ZimZim))

IndicatorsIndicators to to identifyidentify reservoirsreservoirs

Evidence of associationsEvidence of associations

Quantitative data on Quantitative data on riskrisk factorsfactors: case control : case control studiesstudies

IdentifyingIdentifying naturalnatural infection : infection : antibodiesantibodies, virus, virus

ExperimentalExperimental inoculationinoculation

PersistencePersistence of the virus in the of the virus in the reservoirreservoir population = population = longitudinal

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Litterature

review

Rodents

Inoculation on Inoculation on ApodemusApodemus sylvaticussylvaticus, , MicrotusMicrotus

agrestis

agrestis, , MuscardinusMuscardinus avellanariusavellanarius ((DaubneyDaubney, 1931), 1931)

=> suspected of being reservoir => suspected of being reservoir

Heavy mortality inHeavy mortality in ArvicanthisArvicanthis abyssinicusabyssinicus andand

Rattus

Rattus rattusrattus in an in an infectedinfected farmfarm (Kenya, 1932)(Kenya, 1932)

Wild field rat,Wild field rat, ArvicanthisArvicanthis AbyssinicusAbyssinicus, , able to be able to be

infected by RVFV

infected by RVFV, , developed developed viraemiaviraemia without without succumbing to the infection

(5)

Rodents

:

serological

evidence

29.3 (n= 300) 29.3 (n= 300) No No ELISA ELISA Egypt Egypt Rattus

Rattusrattusrattus

2001 2001 50 50 13;5 13;5 4;3 4;3 2;4 2;4 ID ID NT NT Senegal Senegal Rattus

Mastomys

Mastomyshubertihuberti A.Niloticus A.Niloticus M. M. erythroleucuserythroleucus 2000 2000 15 (n=312) 15 (n=312) NT NT ELISA ELISA South

South AfricaAfrica

Aethomys

Aethomysnamaquensisnamaquensis

1997 1997 0.75 (n= 57) 0.75 (n= 57) No No IFI IFI Senegal Senegal Mauritania Mauritania Mastomys Mastomys erythroleucus erythroleucus 1987 1987 3.6 3.6 TDRP TDRP IFI IFI RCA RCA Mastomys Mastomys 1983 1983 19 19 5 5 PRN PRN HI HI Egypt Egypt Gerbillus Gerbillusspsp Meriones

Merionescrassuscrassus

1982 1982 21.5 21.5 8.2 8.2 3.1 3.1 No No HI HI Egypt Egypt A.Niloticus A.Niloticus A.Cahirinus A.Cahirinus Rattus

1978 1978 % % Confirmation test Confirmation test Method Method Location Location Species Species Ref

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Rodents

:

_:

virological

_virological

evidence

_evidence

9.6 (n=300)

RT

RT--PCRPCR

Rattus

Rattus RattusRattus

Egypt Egypt 2001** 2001** 12.5 12.5 (n=8) (n=8) CF CF Rattus

Rattus RattusRattus

Egypt Egypt 1979 1979 ** % positive % positive Test Test Species Species Location Location Year Year •Imam et al, 1979

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Other

species

AntibodiesAntibodies in in wildwild ruminants in Zimbabwe (IHA ruminants in Zimbabwe (IHA confirmedconfirmed by ELISA)by ELISA)

AfricanAfrican buffaloesbuffaloes ((SyncerusSynceruscaffercaffer) 6.2% (n=541)) 6.2% (n=541)

WaterbuckWaterbuck ((KobusKobusellipsiprymnusellipsiprymnus)) 4.5% (n=179) 4.5% (n=179)

White rhino (White rhino (CeratotheriumCeratotheriumsimumsimum)) 8.3% (n=84)8.3% (n=84)

Black rhino (Black rhino (DicerosDicerosbicornisbicornis)) 16% (n=110)16% (n=110)

AntibodiesAntibodies in in AfricanAfrican buffaloesbuffaloes in Kenya (1998) (Davis, 1975)in Kenya (1998) (Davis, 1975)

ViraemiaViraemia afterafter experimentalexperimental inoculation:inoculation:

AfricanAfrican buffaloesbuffaloes ((SyncerusSynceruscaffercaffer) (Kenya, ) (Kenya, DaubneyDaubney 1932) (Davies, 1981)1932) (Davies, 1981)

Abortions in South Abortions in South AfricaAfrica (Joubert, 1951)(Joubert, 1951)

Springboks (Springboks (AntidorcasAntidorcasmarsupialismarsupialis))

DamaliscusDamaliscus ((DamaliscusDamaliscusalbifronsalbifrons))

Presence of antibodies in hippopotami and elephant, and abortionPresence of antibodies in hippopotami and elephant, and abortions in s in

springbok and

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Other

species

BatsBats

Two viral strains isolated from MicropteropusTwo viral strains isolated from Micropteropus pusilluspusillus and and

Hipposideros

Hipposideros abaeabae, with positive serological test on humans and , with positive serological test on humans and

ruminants

ruminants (, (, BoiroBoiroet al.et al.(1987)) , (1987)) , GuineaGuinea

Isolation fIsolation fromrom organ pools of Micropteropusorgan pools of Micropteropus pusillus, pusillus, MiniopterusMiniopterus

schreibersi

schreibersi, and , and HipposiderosHipposideros caffercaffer ((KonstantnovKonstantnovet al.et al.(2006)), (2006)), GuineaGuinea

MonkeysMonkeys

SerosurveySerosurvey on 333 on 333 baboonsbaboons Kenya Kenya (Davies et al, 1971)(Davies et al, 1971)

ExperimentalExperimental inoculation => inoculation => viraemiaviraemia and and antibodiesantibodies))(NiIklasson(NiIklassonet al, et al, 1983)

1983)

AfricanAfrican carnivores carnivores speciesspecies

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Sporadic cases and/or viral isolations and/or infection

serological evidence Enzootic circulation and/ or outbreaks 0 500 1 000 Kilomètres Geographical Geographical distribution distribution and and persistence mechanisms persistence mechanisms ? ?? ? ? ?

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Research

perspectives

Contact betweenContact between livestocklivestock and wildlifeand wildlife

RIFTRIFT--OI MadagascarOI Madagascar

RPRP--PCP ZimbabwePCP Zimbabwe

ExperimentalExperimental infectionsinfections

ViraemiaViraemia levellevel

ViraemiaViraemia durationduration

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RIFT

-

OI

project

Estimation of the incidence Estimation of the incidence on

on livestocklivestock and and riskrisk factorsfactors

Identification of Identification of potentialpotential vectors

vectors and population and population dynamic

dynamic

Identification of Identification of potentialpotential reservoir

reservoir and population and population dynamic

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Expected

results

Assumptions on the Assumptions on the AnjozorobeAnjozorobe ecosystem ecosystem

functioning functioning

?? ??

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Methodology

Sherman traps

Pitfall traps

@Vahatra @Vahatra

(14)

Methodology

1.

Standard mesures (

sex

,

weight

…

)

2.

Tissues

samples

in EDTA,

3.

Organs

and sera

4.

(15)

Overview of ongoing RP-PCP studies in the

SEL of Zimbabwe

M. de Garine-Wichatitsky, A. Caron, et al.M. de

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To

understand

Host

-

Pathogen

Interactions

AtAt the the communitycommunity levellevel::

MultiMulti--hostshosts

MultiMulti--pathogenspathogens

AtAt the the wildlifewildlife//livestocklivestock

interface interface ? ? ? ? ? ?

(17)

- Zoonosis: Brucellosis BTB -Ticks and TBD: Theileria spp Boophilus spp/Babesia spp Amblyomma spp/E.ruminantium - FMD

- Other viral diseases:

RVF, LSD, PPR ...

Research activities 2008

• Prevalence of main diseases and parasites in wild ungulates

40 buffalo, 25 kudu, 40 impala

• Prevalence of main diseases and parasites in domestic ungulates 120 cattle x 3 seasons 3 sites x 60 cattle/goats/sheep

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Research activities in 2008

• Characterisation of the wildlife/livestock interface

Buffalo

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Consequences

in

terms

of control

Given

an

identified

target

-

reservoir

system

Target control?Target control?

Ruminant vaccinationRuminant vaccination

Transmission Transmission blockingblocking strategy?strategy?

FenceFence and FAand FA

ReservoirReservoir control?control?

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Conclusion

More questions More questions thanthan answersanswers !!

IdentifyingIdentifying the the potentialpotential reservoirreservoir

Field Field studiesstudies

ExperimentalExperimental studiesstudies

UnderstandUnderstand itsits rolerole in the in the

epidemiological

epidemiological cyclecycle

ModellingModelling

AdaptAdapt the control the control measuresmeasures to thisto this

cycle cycle

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