Malaria Alerts From Space

With the help of Earth-watching satellites, scientists can identify high-risk "hot spots" for deadly diseases like malaria before outbreaks strike.

Last year more than a million people died of malaria, mostly in Sub-saharan Africa. Outbreaks of Dengue Fever, hantavirus, West Nile Fever, Rift Valley Fever, and even Plague still occasionally strike villages, towns, and whole regions. To the dozens or hundreds who suffer painful deaths, and to their loved ones, these diseases must seem to spring upon them from nowhere.

Yet these diseases are not without rhyme or reason. When an outbreak of malaria occurs, often it is because environmental conditions such as rainfall, temperatures, and vegetation set the stage for a population surge in disease-carrying pests. Mosquitoes or mice or ticks thrive, and the diseases they carry spread rapidly.

So why not watch these environmental factors and warn when conditions are ripe for an outbreak? Scientists have been tantalized by this possibility ever since the idea was first expressed by the Russian epidemiologist E. N. Pavlovsky in the 1960s. Now technology and scientific know-how are catching up with the idea, and a region-wide early warning system for disease outbreaks appears to be within reach.

Image courtesy West Nile Virus Prevention. Mosquitoes and other pests are often to blame for the sudden outbreak of an infectious disease.

Ronald Welch of NASA's Global Hydrology and Climate Center in Huntsville, Alabama, is one of the scientists working to develop such an early warning system. "I have been to malarious areas in both Guatemala and India," he says. "Usually I am struck by the poverty in these areas, at a level rarely seen in the United States. The people are warm and friendly, and they are appreciative, knowing that we are there to help. It feels very good to know that you are contributing to the relief of sickness and preventing death, especially the children."

The approach employed by Welch and others combines data from high-tech environmental satellites with old-fashioned, "khaki shorts and dusty boots" fieldwork. Scientists actually seek out and visit places with disease outbreaks. Then they scrutinize satellite images to learn how disease-friendly conditions look from space. The satellites can then watch for those conditions over an entire region, country, or even continent as they silently slide across the sky once a day, every day.