Empres Transboundary Animal Diseases Bulletin No. These rains create a favourable habitat for the mosquitoes that carry the Rift Valley fever virus, spreading it to humans and animals. Researchers at NASA's Goddard Space Flight Center, Greenbelt, Maryland, and the Department of Defense-Global Disease Infections System, Walter Reed Army Institute of Research, Washington, DC, studied nearly five decades of data to produce these findings. According to their report in the 16 July issue of Science , satellite data can help predict Rift Valley fever outbreaks up to six months in advance. There were large outbreaks every seven to ten years, but the virus apparently disappears between outbreaks.
Satellites provide synchronous measurements of ocean temperature and vegetation conditions.
The close relationship between ocean temperature, rainfall and land vegetation helps scientists determine which areas received the most rain and are greener than normal, making them likely habitats for the mosquitoes that carry the Rift Valley fever virus. This virus is passed into the eggs of Aedes mosquitoes. The mosquitoes lay their eggs in moist soil when floodwaters recede. The young insects hatch when the area is reflooded and feed on local livestock. A second kind of mosquito, the genus Culex , then causes the large outbreaks by contracting the virus from infected livestock and spreading it rapidly.