NASA study predicted outbreak of deadly virus

Published 17 February 2009

Predictive tool is a blend of NASA and National Oceanic and Atmospheric Administration measurements of sea surface temperatures, precipitation, and vegetation cover to predict when and where an outbreak would occur

Yogi Berra said that “Predictions are very difficult, especially about the future.” University of Maryland researcher begs to differ. An early warning system, more than a decade in development, successfully predicted the 2006-7 outbreak of the deadly Rift Valley fever in northeast Africa, according to a new study led by NASA scientists Rift Valley fever is unique in that its emergence is closely linked to interannual climate variability. Utilizing that link, researchers including Assaf Anyamba, a geographer and remote sensing scientist with the University of Maryland Baltimore County and NASA’s Goddard Space Flight Center in Greenbelt, Maryland, used a blend of NASA and National Oceanic and Atmospheric Administration measurements of sea surface temperatures, precipitation, and vegetation cover to predict when and where an outbreak would occur.

The final product, a Rift Valley fever “risk map,” gave public health officials in East Africa up to six weeks of warning for the 2006-7 outbreak, enough time to lessen human impact. The first-of-its-kind prediction is the culmination of decades of research. During an intense El Niño event in 1997, the largest known outbreak of Rift Valley fever spread across the Horn of Africa. About 90,000 people were infected with the virus, which is carried by mosquitoes and transmitted to humans by mosquito bites or through contact with infected livestock.

The 1997 outbreak provoked the formation of a working group — funded by the U.S. Department of Defense Global Emerging Infections Surveillance and Response System — to see whether predictions of an outbreak could be made operational. Such predictions would not only aid mitigation efforts in the endemic countries and protect the global public, but would help protect American civilian and military personnel located and traveling overseas, ensure the safety of imported goods and animals, and prevent infected humans or mosquitoes from entering the United States. “To do all that, we need to understand a disease in the endemic region,” Anyamba said.

The link between the mosquito life cycle and vegetation growth was first described in a 1987 Science paper by co-authors Kenneth Linthicum of the U.S. Department of Agriculture and Compton Tucker of NASA Goddard. Then, a subsequent 1999 Science paper described link between the disease and the El Niño-Southern Oscillation (ENSO). ENSO is a cyclical, global phenomenon of sea surface temperature changes that can contribute to extreme climate events around the world.

For some areas, the warm phase of ENSO brings drought, while in some areas