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Satellites help track West Nile virus
By Marsha Walton (CNN Sci-Tech)
(CNN) -- Satellites track weather, troop movements in wars and trucks on the highway. But track mosquitoes? Almost. NASA scientists are giving U.S. public health officials a different look at how the West Nile virus spreads with the help of images from polar orbiting satellites. "Variations in vegetation, temperature and moisture really dictate where mosquitoes and birds infected with West Nile virus are likely to thrive," said Robert Venezia, NASA program manager for Public Health Applications. "Scientists can then analyze variations in those factors for areas ripe for mosquito infestation." Counting birdsPublic health experts have tracked the spread of the disease in humans since it first appeared in the United States in summer 1999. They have also tried to get a geographic handle on it by following bird migration patterns and by counting birds that have died from the disease. The view from space adds an important dimension to that ground-based detective work. "When they combine our satellite data with their case data, they're able to develop what we're calling 'risk maps.' It helps them focus their response, for a better idea of where to spray, where not to spray, and where to issue an alert or an advisory," Venezia said. More than 30 species of mosquitoes carry the West Nile virus and they all need specific environmental conditions to survive, thrive and spread the disease. NASA's year-round maps of surface temperature, precipitation levels and vegetation density may help scientists pinpoint areas of risk before there is an outbreak. The virus has claimed 146 lives in the United States so far in 2002. While most humans who contract the disease recover, people with compromised immune systems and the elderly can develop fatal encephalitis. Images sharedThe satellite images being shared with public health experts come from NOAA's Advanced Very High Resolution Radiometer Instrument on board polar orbiting earth science satellites. That same technology is used to try to understand the seasonal migration of other diseases such as malaria and Lyme disease. It's also used to monitor air pollution, water quality and other environmental issues that affect public health. Venezia said NASA has a long history of sharing information with the medical community. NASA scientists are sharing imagery with the Centers for Disease Control and Prevention and with public health officials in 33 states affected by the West Nile virus. Much of this research is done by scientists who are part of INTREPID, the International Research Partnership for Infectious Diseases. The group is based at NASA's Goddard Space Flight Center in Maryland.
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