Rift Valley Fever RVF. Enhancing Safe Inter-Regional Livestock Trade Dubai, United Arab Emirates June 13-16, 2011

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3 Rift Valley Fever RVF Enhancing Safe Inter-Regional Livestock Trade Dubai, United Arab Emirates June 13-16, 2011

4 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.

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6 Rift Valley - Kenya, Africa 1900 s: First recognized in sheep 1930: Agent isolated Intermittent outbreaks in Kenya , major epizootic 500,000 sheep abortions 100,000 sheep deaths

7 Egypt: 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

8 Other Important Outbreaks 1987: Senegal, Africa Differed from other outbreaks Not associated with rainfall : Kenya, Africa Largest outbreak reported 89,000 humans cases deaths : Saudi Arabia and Yemen First outbreak outside of Africa 2003: Egypt 45 cases; 17 deaths; All cases were Egyptian farmers

9 Transmission

10 Arthropod vector Mosquitoes Aedes Anopheles Culex Others Biting flies possible vectors

11 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

12 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.

13 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

14 Animals and Rift Valley Fever

15 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%).

16 Lambs and Kids Incubation period: 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%

17 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%

18 Prevention and Control

19 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

20 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

21 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

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23 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.

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25 Endemic in tropical Africa Cyclic epidemics every 5-20 years Abnormally heavy rainfalls Peaks in late summer Outbreaks Saudi Arabia, Yemen, and Egypt

26 Distribution of Rift Valley Fever

27 Saudi Arabia and Yemen 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

28 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 These were accompanied by human disease and abortions in the livestock in the affected villages.

29 Arabian Gulf

30 Control during outbreak In response to the Rift Valley Disease RVD out break, the Ministry of Agriculture applied the following measures: 1. Restriction of animal movement in the affected area which include Gazan, Asir & Tohamet Makah. Restriction also included a surveillance Zoon in NAJRAN and Baha regions. 2. Massive vaccination of all livestock in the infected area Smith burn attenuated vaccine.

31 3. Control of mosquito A- filling of ponds and marshes. B- Rainwater drainage. C- Biocontrol bacillus thuringiensis H14. D- Chemical control pesticides. Aerial and ground spraying by mosquito pesticides codified E-Assess the efficiency of mosquito control mosquito traps.

32 Control after the outbreak After 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.

33 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.

34 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.

35 Post Epidemic Records Shows that All the reported virus activity were Less than 1%, which considered as a characteristic features of RVFV epidemiology in previously infected areas during the inter epizootic period and prove the maintenance cycle of the virus infection. Studies showed no other foci of the disease in non-infected regions (sentinel studies)

36 * 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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