riftvalleyfeversymptoms.ppt

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Rift Valley Fever- 2006

Rift Valley FeverRift Valley FeverSymptomsSymptoms

Texas A&M University University of PretoriaTexas A&M University University of Pretoria

College of Veterinary Medicine Department ofCollege of Veterinary Medicine Department ofVeterinary Tropical DiseasesVeterinary Tropical Diseases

Jeffrey Musser, DVM, PhD ProfessorJeffrey Musser, DVM, PhD ProfessorJ.A.W. CoetzerJ.A.W. Coetzer

Suzanne Burnham, DVMSuzanne Burnham, DVM


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Special thanks for materialsSpecial thanks for materials

borrowed with permissionborrowed with permission

from presentations by:from presentations by:

Dr Linda Logan, Rift Valley Fever CSU Foreign Animal DiseaseDr Linda Logan, Rift Valley Fever CSU Foreign Animal Disease

Training Course, College of Veterinary Medicine and BiomedicalTraining Course, College of Veterinary Medicine and Biomedical

Sciences, August 1-5, 2005.Sciences, August 1-5, 2005.

Professor JAW Coetzer,Professor JAW Coetzer, Department of Veterinary Tropical

Diseases, Faculty of Veterinary Science, University of Pretoria,

Rift Valley Fever presented at the FEAD course in Knoxville,

Tenn. 2005.


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Rift Valley FeverRift Valley Fever

In this presentation the authors especially drew from the first handIn this presentation the authors especially drew from the first handexperience of their colleagues in South Africa. Personal interviewsexperience of their colleagues in South Africa. Personal interviewsas well as standard research sources provide the insights we bringas well as standard research sources provide the insights we bringyou for the recognition of this exotic disease.you for the recognition of this exotic disease.

JAW CoetzerJAW Coetzer

Jeffrey MusserJeffrey Musser

Suzanne BurnhamSuzanne Burnham
http://science.nasa.gov/headlines/y2002/images/rvf/riftvalley_big.jpg


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Rift Valley Fever (RVF)Rift Valley Fever (RVF)is an arthropod-borne,is an arthropod-borne,acute, fever-causingacute, fever-causing

viral disease of sheep,viral disease of sheep,goats, cattle andgoats, cattle andpeople.people.


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Rift Valley fever in Africa causes abortions inRift Valley fever in Africa causes abortions insheep, cattle and goats high mortalities in lambssheep, cattle and goats high mortalities in lambs

and kids and generalized disease in man.and kids and generalized disease in man.


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RVF was first observed whenRVF was first observed whenEuropean stocks of domesticEuropean stocks of domesticanimals were introduced to Africa.animals were introduced to Africa.

These species are more severelyThese species are more severelyaffected than native African stock.affected than native African stock.


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Host RangeHost Range

Mainly a disease of sheepMainly a disease of sheep


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Host RangeHost Range In SheepIn Sheep

Mortality in lambsMortality in lambsunder 2 weeks ofunder 2 weeks ofage approachesage approaches

100%100%

Mortality in older sheepMortality in older sheepreaches 30%reaches 30%

with abortionswith abortionsapproaching 100%approaching 100%


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Host rangeHost range

Cattle are less susceptible than sheep,Cattle are less susceptible than sheep,

some are subclinical; mortality averagessome are subclinical; mortality averages

5% with some abortions5% with some abortions


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GoatsGoats

BuffaloBuffalo


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Domestic dogs and cats susceptible butDomestic dogs and cats susceptible but

usually only have asymptomatic viremiausually only have asymptomatic viremia

Swine - resistantSwine - resistant

Birds - refractory, no virus isolationBirds - refractory, no virus isolation


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Horses have viremia but are resistantHorses have viremia but are resistant


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Host rangeHost range - wildlife- wildlife

SpringbokSpringbok

African BuffaloAfrican BuffaloCamels (in Egypt)Camels (in Egypt)

Water buffalo in EgyptWater buffalo in Egypt


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Water buffalo - up to 50% abortion rateWater buffalo - up to 50% abortion rate



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Camels (in Egypt) - inapparent disease except abortionsCamels (in Egypt) - inapparent disease except abortions



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Rift Valley fever host range and disease severity

Mortality~100%

Severe IllnessAbortion, LowMortality

Severe IllnessViremiaAbortion

InfectionViremia

Refractivetoinfection

Lambs

Calves

Kids

Puppies

Kittens

White mice

Hamster

Field mice

Door mice

Field voles

Sheep

Cattle

Goats

Water buffalo

Monkeys

Camels

Rats

Gray squirrels

Humans

Horses

Cats

Dogs

Monkeys

Guinea pigs

Rabbits

Pigs

Hedgehogs

Tortoises

Frogs

Chickens

Canaries

PigeonsParakeets


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Incubation periodIncubation period

1-6 days1-6 days

12-36 hours in12-36 hours inlambs; will belambs; will be

dead before theydead before they

can acquirecan acquire

passive immunitypassive immunity


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Clinical signsClinical signs

Sheep and GoatsSheep and Goats

Incubation period lessIncubation period less

than 3 daysthan 3 days

High rate of abortionHigh rate of abortion

at any stage ofat any stage of

gestationgestation

Some show noSome show no

symptomssymptoms


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Abortion rate in sheep from 40 100%Abortion rate in sheep from 40 100%

Ewe may also retain the placentaEwe may also retain the placenta

Endometritis is another complication afterEndometritis is another complication afteraborting the fetusaborting the fetus

USDA


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Sheep and GoatsSheep and GoatsEarly signsEarly signs

o Fever 40-41CFever 40-41C

o Loss of appetiteLoss of appetite

o JaundiceJaundice

o WeaknessWeakness


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o Encrustation around theEncrustation around the

muzzle from bloodymuzzle from bloodynasal dischargenasal discharge


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Some develop diarrheaSome develop diarrhea


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Acute death may occurAcute death may occur

in 20-30% of adultsin 20-30% of adults


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Heavy sheep losses

occur

during epidemic


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Clinical Signs in lambs and kidsClinical Signs in lambs and kids

Newborn Lambs, Kids: Most severe inNewborn Lambs, Kids: Most severe in

young lambs under 2wks oldyoung lambs under 2wks old

(mortality has high as 90%)(mortality has high as 90%) fever (40-42C),fever (40-42C),

anorexia,anorexia,

weakness,weakness,


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Clinical Signs in lambs and kidsClinical Signs in lambs and kids

Lambs seem reluctant to move;

they have signs of abdominal pain,

rapid respiration and listlessness.


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Clinical signs in cattleClinical signs in cattle

Anorexia

Weakness

Fetid diarrhea

Often only sign is a

drop in calving rates

Add images


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Calves: fever (40-41C), depression. MortalityCalves: fever (40-41C), depression. Mortality

rate: 10-70% Death occurs about 2-8 daysrate: 10-70% Death occurs about 2-8 days

after the first signs appear.after the first signs appear.

Adults: fever (40-41C), excessive salivation,Adults: fever (40-41C), excessive salivation,

anorexia, weakness, fetid diarrhea, fall in milkanorexia, weakness, fetid diarrhea, fall in milk

yield. Abortion may reach 85% in the herd.yield. Abortion may reach 85% in the herd.

Mortality rate is usually less than 10%Mortality rate is usually less than 10%


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Disease most severe signs are seen inDisease most severe signs are seen in

young animalsyoung animals

Symptoms may be prolonged and willSymptoms may be prolonged and will

include jaundice in some calvesinclude jaundice in some calves

Aborted calves are moderately autolyzed.Aborted calves are moderately autolyzed.


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Dogs: Abortions may occur in adult dogs;Dogs: Abortions may occur in adult dogs;

severe disease and death usually only insevere disease and death usually only in

puppiespuppies

Cats: Death in kittensCats: Death in kittens


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TransmissionTransmission

RVF is primarily transmittedRVF is primarily transmitted

from animal to animal by afrom animal to animal by a

mosquitomosquito

Aedes, Culex, Anopheles,Aedes, Culex, Anopheles,

Erehmapodites, MonsosmiaErehmapodites, Monsosmia


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Necropsy findingsNecropsy findings

Massive hepatitis: hemorrhages, necroticMassive hepatitis: hemorrhages, necroticfoci, marked enlargement, orange-brown,foci, marked enlargement, orange-brown,friable, edematous liver tissuefriable, edematous liver tissue

(If you open a newborn lamb, the liver jumps into your(If you open a newborn lamb, the liver jumps into yourface Coetzer)face Coetzer)

Chocolate-brown digested blood inChocolate-brown digested blood inabomasum, hemorrhages in intestinalabomasum, hemorrhages in intestinalmucosa, free blood in lumenmucosa, free blood in lumen


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Necropsy : new-born lambs

Gall bladder hemorrhage; Abomasum diffuse hemorrhage,serosa has petechial hemorrhage


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Necropsy : adult sheep

May look like plant poisoning


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Necropsy : adult cattle

Close up of gall bladders


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Necropsy : cattle

Spleen with many hemorrhages

h l i


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Necropsy : other lesions

Enlarged

lymph nodes


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Differential DiagnosisDifferential Diagnosis

Abortifacient agentsAbortifacient agents

Agents causing hepatitisAgents causing hepatitis

Agents that cause hemorrhagesAgents that cause hemorrhages


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Differential DiagnosisDifferential Diagnosis

Nairobi sheep diseaseNairobi sheep disease

HeartwaterHeartwater

Ovine enzootic abortionOvine enzootic abortionToxic plantsToxic plants

Bacterial septicemias (Pasteurella,Bacterial septicemias (Pasteurella,

Salmonella, Anthrax)Salmonella, Anthrax)Rinderpest and Peste des petits ruminantsRinderpest and Peste des petits ruminants


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Suspect Rift Valley Fever if:Suspect Rift Valley Fever if:

High mortalities in lambs, kids and calves followingHigh mortalities in lambs, kids and calves followingincrease in mosquito populationsincrease in mosquito populations

Disease is milder in adults than in newbornsDisease is milder in adults than in newborns

Abortions in sheep, goats and cattleAbortions in sheep, goats and cattle

Extensive necrotic liver changesExtensive necrotic liver changes

Influenza symptoms in people working with sick animalsInfluenza symptoms in people working with sick animalsor handling infected carcassesor handling infected carcasses


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Rift Valley FeverRift Valley Fever --

BibliographyBibliography1.1. Linda L Logan, DVM PhD, USDA APHIS AttachLinda L Logan, DVM PhD, USDA APHIS Attach,,North Africa, East Africa, Middle East, Rift ValleyNorth Africa, East Africa, Middle East, Rift ValleyFever CSU Foreign Animal Disease TrainingFever CSU Foreign Animal Disease TrainingCourse, Aug 1-5, 2005.Course, Aug 1-5, 2005.

2.2. ProfessorProfessor J A W Coetzer, Department of VeterinaryTropical Diseases, Faculty of Veterinary Science,University of Pretoria, Rift Valley Fever

3. USAHA, Foreign Animal Diseases, 1992 Edition,

p.311-3174.4. W.A. Geering, A.J. Foreman and M.J. Nunn,W.A. Geering, A.J. Foreman and M.J. Nunn, ExoticExotic

Diseases of AnimalsDiseases of Animals, 1995 Australian Govt, 1995 Australian GovtPublishing Service, Canberra; p.218- 224.Publishing Service, Canberra; p.218- 224.


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An excellent video about Rift Valley Fever is available from:

http://www.up.ac.za/academic/veterinary/depts_vtd_teach/index.htm
http://www.up.ac.za/academic/veterinary/depts_vtd_teach/index.htmhttp://www.up.ac.za/academic/veterinary/depts_vtd_teach/index.htm


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Image WatermarkImage Watermark

KAW images by Dr. Ken A. WaldrupKAW images by Dr. Ken A. Waldrup

Coetzer images used with permission byCoetzer images used with permission by

Dr. Koos CoetzerDr. Koos Coetzer

LLogan images by Dr. Linda LoganLLogan images by Dr. Linda Logan

Suz images by Dr Suzanne BurnhamSuz images by Dr Suzanne Burnham

MFitilodze images by Dr.MFitilodze images by Dr. M. W. (Bill)M. W. (Bill)Mfitilodze Bunda College of Agriculture,Mfitilodze Bunda College of Agriculture,

University of MalawiUniversity of Malawi


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AcknowledgementsAcknowledgements

Special thanks toSpecial thanks to

Professor JAW CoetzerProfessor JAW Coetzer

Linda Logan, DVM PhD,Linda Logan, DVM PhD,

USDAUSDA

Ken Waldrup, DVM, PhDKen Waldrup, DVM, PhD

Robin Sewell, DVMRobin Sewell, DVM

Kelsey Pohler- Research AssistantKelsey Pohler- Research Assistant

riftvalleyfeversymptoms.ppt

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