In a pair of recent reports, NASA earth scientists have studied weather changes and subsequent outbreaks of two viral hemorrhagic fevers prevalent in Africa: Rift Valley Fever (RVF) and Ebola. The diseases are dissimilar -Ebola only afflicts people in tropical forest areas, while RVF is deadly to livestock and occasionally to people in semi-arid regions. But both are more likely to spread when the right climatic conditions exist-conditions which can be observed by satellite months in advance.

"Satellite data can be an important tool for public health disease surveillance," said Dr. Assaf Anyamba, a research scientist at NASA's Goddard Earth Sciences Technology Center. "Once we learn more, we could be able to predict climatically-linked outbreaks before they occur." While the study on RVF was conclusive, the Ebola study was limited by the small number of Ebola outbreaks which occurred over the past 20 years.

The two studies, which will appear in an upcoming special issue of Photogrammatic Engineering on Remote Sensing and Human Health, will provide further evidence that climate variability can affect disease patterns. They come fast on the heels of recent NASA research that connects outbreaks of the South American disease Bartonellosis with the appearance of the weather phenomenon El Nio.

Accurate prediction of epidemics is still years away. But in the short term, satellite monitoring could still benefit public health in developing countries where resources to combat disease are limited.

"It is not feasible to send health workers everywhere," Anyamba said. "But if we know where outbreaks are likely, those areas can be targeted. We can focus our efforts where they are needed."

Locating those areas requires the use of polar orbiting satellites, such as the Terra sate
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Contact: Cynthia M. O'Carroll
cocarrol@pop100.gsfc.nasa.gov
301-614-5563
NASA/Goddard Space Flight Center
5-Feb-2002