title: The use of veterinary vaccines for prevention and control of Rift Valley fever: memorandum from a WHO/FAO meeting.
abstract: This Memorandum considers the use of veterinary vaccines for the prevention of Rift Valley fever (RVF) and for its control during outbreaks. Veterinary vaccines are the first line of defence against RVF. Existing live and inactivated vaccines have been used extensively in Africa but further development of both is warranted. The live virus vaccine may cause abortion and its potential for reversion to virulence has not been adequately investigated. It should be used only in enzootic and epizootic areas. The inactivated vaccines are effective and safe, but they are more expensive and at least 2 doses must be given. They are currently produced only in Egypt and South Africa. Diagnosis of RVF is made by isolation of virus or demonstration of an elevated serum antibody titre. Reference laboratories are available to assist in the diagnosis. In the event of an outbreak of RVF, the appropriate international authorities should be notified and immunization of livestock should be carried out according to the guidelines described herein. Movement of animals should be controlled during epizootics. Guidelines for action for neighbouring countries are also given. The immunization policies recommended for sub-Saharan Africa differ from those for areas beyond the enzootic range, where use of killed vaccine only is recommended. The enzootic and epizootic areas in East Africa are characterized according to their ecology. The description serves as a predictive guide for other parts of Africa and can aid in setting immunization policy. Recommended WHO specifications are given for the inactivated RVF vaccine, including description of substrates, seed virus, potency, and safety testing. Future research needs include experiments on potency, thermal stability, adjuvants, immunity, virus markers, and genetic stability. Longer-term vaccine development envisages reassortant vaccines, gene cloning to produce recombinant DNA products, and synthetic polypeptide vaccines.
mesh_terms: D000818:Animals; D002043:Bunyaviridae / Q000276:immunology*; D002417:Cattle; D002418:Cattle Diseases / Q000517:prevention & control*; D006041:Goats; D006801:Humans; D012295:Rift Valley Fever / Q000517:prevention & control*; D012296:Rift Valley fever virus / Q000276:immunology*; D012756:Sheep; D012757:Sheep Diseases / Q000517:prevention & control*; D014613:Vaccines, Attenuated; D014765:Viral Vaccines / Q000627:therapeutic use*
chemical_list: D014613:Vaccines, Attenuated; D014765:Viral Vaccines