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5th year 2nd semesterZoonoses
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Dr. Heba AhmedSunday, 20th , March, 2011
IntroductionRVF is a viral zoonoses that was first
identified in Kenya in 1931.
primarily affects animals but also has the capacity to infect humans.
EtiologyRNA virus belongings to family Bunyviridae,
genus phlebovirusenveloped, single stranded negative sense
RNA virus with 80-120 nm diameter. The genome consists of three segments:1- Large segment (L)2- Medium segment (M)3- Small segment (S)
Animal ReservoirCattle, sheep, camels and goatsOther animals : African buffalo, black rhino,
impala, African elephant, waterbuck and horses
The virus is spread among animals by the bite of infected mosquitoes
Age AbortionPMNewborn lambs infected in utero
Insect vectorMosquitoesAedes is the species incriminated in
biological transmissionGlossina, Culicoides, Culex and sand flies offspring
Transmission in humans1- The majority of human infections result from
direct or indirect contact with blood or organs of infected animals
2- Inhalation of aerosols3- Ingestion of unpasteurized or raw milk from
infected animals4- Bites of infected mosquitoes5- Bites of hematophagous (blood-feeding) flies6- Vertical transmission7- Contaminated wind 8- No evidence of human to human transmission
OccurrenceYearLocality
1931Great rift valley, Kenya
1950-1951, 1953, 1956, 1969South Africa
1975South Africa
1977-1978Egypt
1993Egypt
1997-1998Kenya, Somalia, Tanzania
2000-2001Saudi Arabia, Yemen
2003Egypt
2007Kenya and Somalia
2007-2008Sudan
2010South Africa
Occurrence
OccurrenceThere is a potential of epizootics and
epidemics to spread to areas that were previously unaffected
High prevalence of the disease is reported during periods of heavy rainfall
Clinical Picture In Humans
Clinical Picture In HumansOcular formMeningeo-
encephalitis formHaemorrhagic fever form
0.5-2% of patients<1% of patients<1% of patients
Lesions 1-3 weeks after mild symptoms
Lesions 1-4 weeks after mild symptoms
Lesions 2-4 days after mild symptoms
SymptomsSymptomsSymptoms
Death uncommonDeath late is lowDeath within 3-6 days of symptoms
Prevention and Control1- Vaccination:A- Smithburn vaccineB- Formalin inactivated vaccineC- Attenuated MP12 vaccineD- Clone 13E- Sub-unit recombinant vaccine
Prevention and Control2- Vector control
3- Public health education
What are the reasons of considering RVF an important zoonotic disease world [email protected]