Rift Valley fever, human, bovine - Madagascar

Source: World Health Organisation (WHO), EPR, Outbreak News [edited]<http://www.who.int/csr/don/2008_04_18a/en/index.html>
<http://www.who.int/mediacentre/factsheets/fs207/en/>

Rift Valley Fever (RVF) is a viral zoonosis that primarily affects animals but also has the capacity to infect humans. Infection can cause severe disease in both animals and humans, leading to high rates of disease and death. The disease also results in significant economic losses due to death and abortion among RVF-infected livestock."
(Human disease is preceded by animal disease and the cases of human disease described in the preceding report are indicative of the existence of extensive disease in livestock. Rift Valley fever virus has circulated in livestock in Madagascar for several years -- see the ProMED-mail references listed below. - Mod.CP)
"RVF virus is a member of the genus _Phlebovirus_, one of the 5 genera in the family _Bunyaviridae_. The virus was 1st identified in1931 during an investigation into an epidemic among sheep on a farm in the Rift Valley of Kenya. Since then, outbreaks have been reported in sub-Saharan and North Africa. In 1997-98, a major outbreak occurred in Kenya, Somalia and Tanzania and in September 2000, RVF cases were confirmed in Saudi Arabia and Yemen, marking the 1st reported occurrence of the disease outside the African continent and raising concerns that it could extend to other parts of Asia and Europe.
"The vast majority of human infections result from direct or indirect contact with the blood or organs of infected animals. The virus can be transmitted to humans through the handling of animal tissue during slaughtering or butchering, assisting with animal births, conducting veterinary procedures, or from the disposal of carcasses or fetuses.
"Certain occupational groups such as herders, farmers, slaughterhouse workers and veterinarians are therefore at higher risk of infection. The virus infects humans through inoculation; for example, via a wound from an infected knife or through contact with broken skin, or through inhalation of aerosols produced during the slaughter of infected animals. The aerosol mode of transmission has also led to infection in laboratory workers.
"There is some evidence that humans may also become infected with RVF by ingesting the unpasteurized or uncooked milk of infected animals. Human infections have also resulted from the bites of infected mosquitoes, most commonly the _Aedes_ mosquito. Transmission of RVF virus by hematophagous (blood-feeding) flies is also possible.
"To date, no human-to-human transmission of RVF has been documented, and no transmission of RVF to health care workers has been reported when standard infection control precautions have been put in place.