AfricanHorseSicknessAfricanHorseSickness TexasA&MUniversityTexasA&MUniversity CollegeofVeterinaryMedicineCollegeofVeterinaryMedicine JeffreyJeffrey Musser,Musser, DVM,DVM, PhD,PhD, DABVPDABVP SuzanneSuzanne Burnham,Burnham, DVMDVM 20062006 SpecialthanksformaterialsSpecialthanksformaterials borrowedwithpermissionborrowedwithpermission frompresentationsby:frompresentationsby: DrCorrieBrown,DrCorrieBrown, ““AfricanHorseSicknessAfricanHorseSickness ”” CSUForeignAnimalDiseaseTrainingCourse,CSUForeignAnimalDiseaseTrainingCourse, CollegeofVeterinaryMedicineandBiomedicalCollegeofVeterinaryMedicineandBiomedical Sciences,August1Sciences,August1 --5,2005.5,2005. ProfessorAlanGuthrie,DepartmentofProfessorAlanGuthrie, VeterinaryTropicalDiseases,Facultyof VeterinaryScience,UniversityofPretoria, “AfricanHorseSickness” presentedatthe FEADcourseinKnoxville,Tenn.2005. ImagesImages PathologicallesionimagesmarkedPathologicallesionimagesmarked ““USDAUSDA ”” weretakenbystaffphotographersweretakenbystaffphotographers atthePlumIslandAnimalDiseaseCenteratthePlumIslandAnimalDiseaseCenter labandwerepresentedbyDrCorrielabandwerepresentedbyDrCorrie BrownBrown ImagesofsymptomsmarkedImagesofsymptomsmarked ““GuthrieGuthrie ”” werepresentedinTennesseebyDrAlanwerepresentedinTennesseebyDrAlan GuthrieGuthrie AfricanHorseSicknessAfricanHorseSickness EtiologyEtiology HostrangeHostrange IncubationIncubation ClinicalsignsClinicalsigns TransmissionTransmission DiagnosisDiagnosis DifferentialDiagnosisDifferentialDiagnosis AfricanHorseSickness AfricanHorseSicknessAfricanHorseSickness Africanhorsesickness(AHS)isAfricanhorsesickness(AHS)is aninfectiousbutaninfectiousbut noncontagious,insectnoncontagious,insect --borneborne viraldiseaseaffectingallviraldiseaseaffectingall speciesofequids.speciesofequids. ItistransmittedinthefieldbyItistransmittedinthefieldby atleasttwospeciesofatleasttwospeciesof CulicoidesCulicoides .. AfricanHorseSickness AfricanHorseSicknessisanOIEreportablediseaseAfricanHorseSicknessisanOIEreportabledisease.. AfricanHorseSickness If you hear hoof beats, look for horses…. www.hedweb.com/animalag/horsesw.htm AfricanHorseSickness But don’t forget to look for zebras too http:// http://www.singerhuette.at/Afrika/Serengeti%202%202003.htm AfricanHorseSickness AfricanHorseSicknessintheWorldin2004.OIE http://www.oie.int/eng/info/en_presdistribgeo.htm Diseasereportedpresent Diseasereportedabsent Dataunavailableorincomplete AfricanHorseSickness EtiologyEtiology AfricanHorseSicknessiscausedbyanAfricanHorseSicknessiscausedbyan OrbivirusOrbivirus ofthefamilyofthefamily ReoviridaeReoviridae ViscerotropicViscerotropic virusvirus Family:Family: ReoviridaeReoviridae ,Genus:,Genus: OrbivirusOrbivirus NinedifferentserotypesofthevirusNinedifferentserotypesofthevirus havebeendescribedhavebeendescribed AfricanHorseSickness SerotypesSerotypes $OOVHURW\SHVRI$+6$OOVHURW\SHVRI$+6 YLUXVRFFXULQHDVWHUQYLUXVRFFXULQHDVWHUQ DQGVRXWKHUQ$IULFDWKLVDQGVRXWKHUQ$IULFDWKLV GLVWULEXWLRQUHIOHFWVWKHGLVWULEXWLRQUHIOHFWVWKH JHRJUDSKLFSDWWHUQRIJHRJUDSKLFSDWWHUQRI ]HEUDZKLFKF\FOHWKH]HEUDZKLFKF\FOHWKH YLUXVDV\PSWRPDWLFDOO\YLUXVDV\PSWRPDWLFDOO\ DQGSUREDEO\VHUYHDVDDQGSUREDEO\VHUYHDVD UHVHUYRLUIRUWKHYLUXVUHVHUYRLUIRUWKHYLUXV AfricanHorseSickness SerotypesSerotypes 2QO\$IULFDQ+RUVH2QO\$IULFDQ+RUVH 6LFNQHVVYLUXVVHURW\SH6LFNQHVVYLUXVVHURW\SH LVIRXQGLQ:HVW$IULFDLVIRXQGLQ:HVW$IULFD ZKHUH]HEUDGRQRWZKHUH]HEUDGRQRW RFFXURFFXU AfricanHorseSickness SerotypesSerotypes 3HULRGLFDOO\$+6YLUXV3HULRGLFDOO\$+6YLUXV VSUHDGVEH\RQGVXEVSUHDGVEH\RQGVXE 6DKDUDQ$IULFDDQGWKH6DKDUDQ$IULFDDQGWKH GLVHDVHKDVFDXVHGGLVHDVHKDVFDXVHG PDMRUHSL]RRWLFVPDMRUHSL]RRWLFV H[WHQGLQJDVIDUDVH[WHQGLQJDVIDUDV 3DNLVWDQDQG,QGLDLQWKH3DNLVWDQDQG,QGLDLQWKH HDVWDQG0RURFFR6SDLQHDVWDQG0RURFFR6SDLQ DQG3RUWXJDOLQWKH:HVWDQG3RUWXJDOLQWKH:HVW AfricanHorseSickness VirusCharacteristicsVirusCharacteristics Theviruscanbeinactivatedby: repeatedfreezingandthawing bytreatmentwithaceticacid(atpHof 6.3or lower),remainingfor2weeksat 37°C,orbeingplacedfor5minutesat 70°C. AfricanHorseSickness HostRangeHostRange InorderofdecreasingseverityofInorderofdecreasingseverityof disease:disease: HorsesHorses MulesMules DonkeysDonkeys ZebrasZebras AfricanHorseSickness Approximately70Approximately70 --95percentofallhorses95percentofallhorses developingthediseasewilldiedevelopingthediseasewilldie AfricanHorseSickness yetthemortalitypercentageforyetthemortalitypercentagefor mulesisonlyabout50percentmulesisonlyabout50percent andfordonkeysonly10percent.andfordonkeysonly10percent. AfricanHorseSickness RoleofZebrasRoleofZebras AHSvirusoverAHSvirusover -- wintersinzebraswintersinzebras inKrugerinKruger NationalPark,NationalPark, fromwhereitfromwhereit spreadsspreads westwardsandwestwardsand southwardssouthwards ImagecourtesyofDrCorrieBrown everyyear. everyyear. AfricanHorseSickness ZebrasZebras AHSremainsAHSremains endemicinzebraendemicinzebra populationsacrosspopulationsacross SouthAfricaSouthAfrica TheyharborthevirusTheyharborthevirus andareoftentheandareoftenthe sourceofsuddensourceofsudden outbreaksinAfricaoutbreaksinAfrica AfricanHorseSickness HostRangeHostRange DogscanalsobecomeinfectedbyDogscanalsobecomeinfectedby eatinginfectedmeat.eatinginfectedmeat. 19871987 --90outbreakinSpain:90outbreakinSpain: DogsthatdidnotconsumeinfectedDogsthatdidnotconsumeinfected meatwerefoundtobemeatwerefoundtobe seropositiveseropositive ,, suggestinginfectionbyarthropodsuggestinginfectionbyarthropod bites.bites. AfricanHorseSickness HostRangeHostRange ThereisnoevidencethathumanscanbeThereisnoevidencethathumanscanbe infectedbyfieldstrainsofthedisease.infectedbyfieldstrainsofthedisease. However,intranasalexposuretoHowever,intranasalexposureto neurotrophicneurotrophic vaccinestrainshascausedvaccinestrainshascaused encephalitisandretinitisinhumans.encephalitisandretinitisinhumans. AfricanHorseSickness IncubationIncubation Inexperiments,AfricanHorseSicknessInexperiments,AfricanHorseSickness usuallyhasa5to7dayincubationusuallyhasa5to7dayincubation period.period. Innaturalinfections,circumstantialInnaturalinfections,circumstantial evidenceindicatesthattheincubationevidenceindicatesthattheincubation periodisfrom7to14days.periodisfrom7to14days. AfricanHorseSickness ClinicalSignsClinicalSigns InfectedhorsesremainviremicforInfectedhorsesremainviremicfor approximately18days,althoughthefeverapproximately18days,althoughthefever maybepresentforanother4to8days,ifmaybepresentforanother4to8days,if theanimalshouldlivethatlong.Despitetheanimalshouldlivethatlong.Despite theirreducedmortality,theviremicstagetheirreducedmortality,theviremicstage indonkeysmaylastforupto28days.indonkeysmaylastforupto28days. ZebrasappeartobeverysimilartoZebrasappeartobeverysimilarto donkeysinthisregard.donkeysinthisregard. AfricanHorseSickness ClinicalSignsClinicalSigns FirstSign:FirstSign: Feverof102Feverof102 °°FF toto 106106 °°F,F, (38.9(38.9 °°CC -- 41.141.1 °°C)C) AfricanHorseSickness ClinicalSignsClinicalSigns MostCommonSignMostCommonSign CongestionofCongestionof theconjunctivaetheconjunctivae SeverityofSeverityof congestioniscongestionis goodindicationgoodindication ofseverityofofseverityof infectioninfection AfricanHorseSickness ClinicalSignsClinicalSigns LowerEyelidConjunctivitisLowerEyelidConjunctivitis AfricanHorseSickness ClinicalSignsClinicalSigns Afterinitialsigns,thediseasecan progressinoneoffourways: Peripheral(Cardiac)called“Dikkop” inS. Africa Central(Pulmonary)called“Dunkop” inS. Africa MixedForm(Acute) MixedForm(Fever) AfricanHorseSickness ClinicalSigns:ClinicalSigns: PulmonaryPulmonary Feverupto104Feverupto104 °°FF to106to106 °°FF IncreasinglymoreIncreasinglymore rapidrespirationrapidrespiration andabdominalandabdominal expirationexpiration Respiratoryratemay reach60 -70per minute http://www.vet.ed.ac.uk/animalpain/Pages/images/Optimised CoughingandCoughingand %20Images/optphotos/EQsweating.jpg SweatingSweating AfricanHorseSickness ClinicalSigns:PulmonaryClinicalSigns:Pulmonary HorsemayappearHorsemayappear colicky(gettingupcolicky(gettingup anddown,andanddown,and rolling)rolling) AspulmonaryAspulmonary distressincreases:distressincreases: Animalstandswith forelegsapart Headextended Nostrilsdilated AfricanHorseSickness ClinicalSigns:PulmonaryClinicalSigns:Pulmonary OncefoamOncefoam appearsappears innostrils,innostrils, deathdeath followsrapidly.followsrapidly. Animalmaydrinkandeat,eveninterminalstages.Animalmaydrinkandeat,eveninterminalstages. AfricanHorseSickness ClinicalSigns:PulmonaryClinicalSigns:Pulmonary PhotocourtesyofPlumIsland AfricanHorseSickness Inmyfewencounterswiththedisease,IwasInmyfewencounterswiththedisease,Iwas struckbytheextremestruckbytheextreme respiratorydistressincludingfrothpouringfromtrespiratorydistressincludingfrothpouringfromthehe nostrils,nostrils, extensivehydrothoraxandextensivehydrothoraxand hydropericaridiumhydropericaridium ,, supraorbitalsupraorbital edemaandaedemaanda gelatinousinfiltrationofsubcutaneoustissueandgelatinousinfiltrationofsubcutaneoustissueand intermuscularintermuscular fascialfascial planesalongtheplanesalongthe ligamentumligamentum nuchaenuchae andand musclesofthemusclesofthe shoulder.shoulder. Dr Botlhe Modisane 2006 AfricanHorseSickness In2004,SouthAfricareported196outbreaksIn2004,SouthAfricareported196outbreaks resultingin335casesresultingin335cases and166deaths.Thecasefatalityratewasevenand166deaths.Thecasefatalityratewaseven higherin2003,withhigherin2003,with 89outbreaksresultingin510casesand44189outbreaksresultingin510casesand441 deaths.Priortothisdeaths.Priortothis outbreak,theWesternCapeprovincehadbeenoutbreak,theWesternCapeprovincehadbeen declaredanAHSdeclaredanAHS