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Rift Valley Fever                 RVF  Enhancing Safe Inter-Regional Livestock Trade          Dubai, United Arab Emirates ...
Definition• Rift valley fever (RVF) is an acute  febrile    arthropod-borne     zoonotic  disease. It is characterized by ...
Rift Valley - Kenya, Africa• 1900’s: First recognized in sheep• 1930: Agent isolated• Intermittent outbreaks in Kenya  – 1...
Egypt: 1977-1978• Humans  – 18,000 cases  – 598 deaths    • Encephalitis and hemorrhagic      fever    • Case-fatality les...
Other Important Outbreaks• 1987: Senegal, Africa  – Differed from other outbreaks    • Not associated with rainfall• 1997-...
• Transmission
• Arthropod vector  – Mosquitoes    • Aedes    • Anopheles    • Culex    • Others• Biting flies possible vectors
Other Modes of Transmission• Direct contact or Aerosol  – Tissues or body fluids of infected animals     • Aborted fetuses...
Reservoir• Mosquitoes – Aedes species  – Transovarial transmission  – Eggs dormant in soil     for long periods  – Heavy r...
Amplifying Hosts• Infected livestock• High levels of viremia• Amplifying  – Sufficient to infect mosquito vectors  – Estab...
• Animals and Rift Valley Fever
Sheep and Goats• Incubation period: less than 3 days   – High rate of abortion (5-100%)      • Any stage of gestation   – ...
Lambs and Kids• Incubation period: 12-36 hrs• Newborn deaths  – High fever, listless, anorexia  – Death - 12 hours to 2 da...
Cattle• Adults  – Fever, weakness,    anorexia, ptyalism,   fetid diarrhea, icterus  – Death - Mortality 10%  – Abortion c...
• Prevention and Control
Prevention• Vaccination of ruminants by using attenuated  virus vaccine prepared from Smith burn  strain which prohibited ...
Control• Do not slaughter sick animals  – Bury or burn carcasses during an outbreak• Personal protective equipment  – Glov...
Control• Clean animal housing areas  – Wear personal protective equipment  – Remove all organic materials from    surfaces...
Attenuated tissue culture            vaccine• Vaccination    of     lambs   with  attenuated virus vaccine prepared  from ...
• Endemic in  tropical Africa  – Cyclic epidemics    every 5-20 years  – Abnormally heavy rainfalls  – Peaks in late summe...
Distribution of Rift   Valley Fever
Saudi Arabia and Yemen            2000-2001• 683 humans hospitalized• 95 deaths (13.9% mortality)• 82.7% male• Median age:...
• An epizootic of Rift Valley fever  was identified in southwest  Saudi Arabia following the  confirmation of        cases...
Arabian Gulf
Control during outbreakIn response to the Rift Valley Disease“RVD” out break, the Ministry of Agricultureapplied the follo...
3. Control of mosquitoA- filling of ponds and marshes.B- Rainwater drainage.C- Biocontrol  bacillus thuringiensis H14.D- ...
Control after the outbreakAfter the end of the epidemic the program  continued with the following measures:• Vaccination o...
• Regular examination and serological testing  of sentinel herds distributed in different  localities of the infected zone...
• Restriction of Animal’s movements:  Measures to control the transmission of  infected animals from infected regions to  ...
Post Epidemic Records Shows that   All the reported virus activity “ were Lessthan    1%,     which     considered    as  ...
* For this reason RVF disease control  program continued :   Mainly to increase the level of animal immunity and increase ...
Rift Valley fever
Rift Valley fever
Rift Valley fever
Rift Valley fever
Rift Valley fever
Rift Valley fever
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Rift Valley fever

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Presentation by Dr Mohamed Hassan of the Ministry of Agriculture, Kingdom of Saudi Arabia, at the Enhancing Safe Inter-regional Livestock Trade held at Dubai, UAE, 13-16 June 2011.

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Transcript of "Rift Valley fever"

  1. 1. Rift Valley Fever RVF Enhancing Safe Inter-Regional Livestock Trade Dubai, United Arab Emirates June 13-16, 2011
  2. 2. Definition• Rift valley fever (RVF) is an acute febrile arthropod-borne zoonotic disease. It is characterized by high rates of abortion and neonatal mortality in sheep, goats and cattle. It causes hemorrhagic fever, encephalitis, blindness and sever liver damage in man.
  3. 3. Rift Valley - Kenya, Africa• 1900’s: First recognized in sheep• 1930: Agent isolated• Intermittent outbreaks in Kenya – 1950-51, major epizootic • 500,000 sheep abortions • 100,000 sheep deaths
  4. 4. Egypt: 1977-1978• Humans – 18,000 cases – 598 deaths • Encephalitis and hemorrhagic fever • Case-fatality less than 1%• Ruminants – Abortions and deaths • Sheep, cattle, goats • Water buffalo, and camels
  5. 5. Other Important Outbreaks• 1987: Senegal, Africa – Differed from other outbreaks • Not associated with rainfall• 1997-98: Kenya, Africa – Largest outbreak reported – 89,000 humans cases - 478 deaths• 2000-01: Saudi Arabia and Yemen – First outbreak outside of Africa• 2003: Egypt – 45 cases; 17 deaths; All cases were Egyptian farmers
  6. 6. • Transmission
  7. 7. • Arthropod vector – Mosquitoes • Aedes • Anopheles • Culex • Others• Biting flies possible vectors
  8. 8. Other Modes of Transmission• Direct contact or Aerosol – Tissues or body fluids of infected animals • Aborted fetuses . During slaughtering and necropsy – High levels of virus in blood • Aerosol • Amplify virus – Infect other mosquitoes – Establish disease in environment – May lead to large outbreaks• No person-to-person transmission – Humans are a possible source of virus for mosquitoes
  9. 9. Reservoir• Mosquitoes – Aedes species – Transovarial transmission – Eggs dormant in soil for long periods – Heavy rainfall, eggs hatch• Ruminant amplifying host• Secondary vectors can be infected – Culex and Anopheles mosquito species – Biting flies: midges, phlebotomids, stomoxids.
  10. 10. Amplifying Hosts• Infected livestock• High levels of viremia• Amplifying – Sufficient to infect mosquito vectors – Establishes disease in environment – Leads to large epizootic epidemics• Humans – Viremia enough to amplify
  11. 11. • Animals and Rift Valley Fever
  12. 12. Sheep and Goats• Incubation period: less than 3 days – High rate of abortion (5-100%) • Any stage of gestation – Asymptomatic – Foul diarrhea, icterus, mucopurulent nasal discharge – Acute death (20-30%).
  13. 13. Lambs and Kids• Incubation period: 12-36 hrs• Newborn deaths – High fever, listless, anorexia – Death - 12 hours to 2 days – Less than 1 week old • Mortality >90%• Lambs and kids over 2 weeks old – Mortality over 20%
  14. 14. Cattle• Adults – Fever, weakness, anorexia, ptyalism, fetid diarrhea, icterus – Death - Mortality 10% – Abortion can be up to 100%• Calves – Similar signs to lambs and kids – Mortality 10-70%
  15. 15. • Prevention and Control
  16. 16. Prevention• Vaccination of ruminants by using attenuated virus vaccine prepared from Smith burn strain which prohibited in pregnant animals as it causes birth defects and abortions.• Avoid and control vectors• Personal protective equipment – Aborted fetuses, necropsy• Avoid contact with infected tissues and blood• Restrict movement of animals• Precautions when traveling
  17. 17. Control• Do not slaughter sick animals – Bury or burn carcasses during an outbreak• Personal protective equipment – Gloves, coveralls, boots, eyewear, mask• Avoid contact with infected tissues and blood – Aborted fetuses, necropsy• Greatest risk to travelers
  18. 18. Control• Clean animal housing areas – Wear personal protective equipment – Remove all organic materials from surfaces (manure, feed, animal tissue) – Use soap or detergent with warm water – Let dry• Disinfect animal housing areas – 1 part bleach:10 parts water
  19. 19. Attenuated tissue culture vaccine• Vaccination of lambs with attenuated virus vaccine prepared from Smith burn strain at age less than 6 months.• it is not safe to use for vaccination of pregnant animals as it cause abortion.
  20. 20. • Endemic in tropical Africa – Cyclic epidemics every 5-20 years – Abnormally heavy rainfalls – Peaks in late summer• Outbreaks – Saudi Arabia, Yemen, and Egypt
  21. 21. Distribution of Rift Valley Fever
  22. 22. Saudi Arabia and Yemen 2000-2001• 683 humans hospitalized• 95 deaths (13.9% mortality)• 82.7% male• Median age: 50 years• Youngest patient: 14 yrs. old• 76% had close contact with animals
  23. 23. • An epizootic of Rift Valley fever was identified in southwest Saudi Arabia following the confirmation of cases in humans in the third week of September 2000. These were accompanied by human disease and abortions in the livestock in the affected villages.
  24. 24. Arabian Gulf
  25. 25. Control during outbreakIn response to the Rift Valley Disease“RVD” out break, the Ministry of Agricultureapplied the following measures:1. Restriction of animal movement in theaffected area which include Gazan, Asir &Tohamet Makah. Restriction also included asurveillance Zoon in NAJRAN and Baharegions.2. Massive vaccination of all livestock in theinfected area  Smith burn attenuatedvaccine.
  26. 26. 3. Control of mosquitoA- filling of ponds and marshes.B- Rainwater drainage.C- Biocontrol  bacillus thuringiensis H14.D- Chemical control  pesticides. Aerial and ground spraying by mosquito pesticides  codifiedE-Assess the efficiency of mosquito control  mosquito traps.
  27. 27. Control after the outbreakAfter the end of the epidemic the program continued with the following measures:• Vaccination of animals at 6 month old.• Active disease surveillance for suspected cases in live stock (flocks with abortion and or early newborn mortalities).• Clinical and serological testing of suspected smuggled animals at Al-Twal quarantine station on the border with Yemen Republic.
  28. 28. • Regular examination and serological testing of sentinel herds distributed in different localities of the infected zone.• During the rainy season (August-October) random serum samples from susceptible animal were examined by both capture ELISA kits for (IgM) and (IgG) RVF antibodies for detection of early infection "IgM" and monitoring the level of immunity due to vaccination (prevalence study),• Rt-PCR was also used for RV virus detection in periodically collected mosquitoes.
  29. 29. • Restriction of Animal’s movements: Measures to control the transmission of infected animals from infected regions to other regions includes:- Quarantine of animals for 30 days.- Animal Marking.- Testing animal’s serum for antibodies (IgG).- Vaccination of animals within 7 days.
  30. 30. Post Epidemic Records Shows that All the reported virus activity “ were Lessthan 1%, which considered as acharacteristic features of RVFV epidemiologyin previously infected areas during the interepizootic period and prove the maintenancecycle of the virus infection. Studies showed no other foci of thedisease in non-infected regions (sentinelstudies)
  31. 31. * For this reason RVF disease control program continued : Mainly to increase the level of animal immunity and increase awareness of animal breeders about the importance of vaccination.
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