Rather than searching for weird weather or enemy missiles, some satellites are helping researchers to track—and predict—the spread of deadly diseases.

With the pandemic spread of H1N1 swine flu and the continued advance of the H5N1 avian flu, scientists are anxious to better predict the spread of infectious diseases and are looking for new tools wherever they might be—even if that's hundreds of miles in the sky.

"Ideally we could predict conditions that would result in some of these major outbreaks of cholera, malaria, even avian flu," says Tim Ford of the University of New England in Biddeford, Maine. Ford and a group of experts have co-authored a perspective paper (pdf), due out next month in Emerging Infectious Diseases, that proposes making use of environmental data—tracked via satellite—to predict disease outbreaks.

"As climate changes, and even with many of our weather patterns, [it] directly affects the distribution of disease," Ford says. Hantavirus, the pulmonary disease spread by rodents, for example, has been linked to changes in precipitation. With more rainfall, vegetation increases, which then fuels rodent populations. And pinpointing an area as relevant conditions emerge—before an outbreak starts—buys precious time to spread public health messages.

Satellite imaging can also help warn of cholera outbreaks, which are predicted to worsen with climate change. The satellites provide information about water surface temperatures, which are key to the spread of this waterborne disease. One study found that giving people simple preventative instructions, such as filtering water through a sari cloth, reduced cholera-related deaths by an estimated 50 percent in some areas.

Remote data have already been used to map the avian flu in Asia. Xiangming Xiao, associate director of the University of Oklahoma's Center for Spatial Analysis in Norman, has been tracking likely outbreaks of this highly pathogenic flu by looking for key habitat and weather changes. The domestic duck—determined to be the main carrier of the disease—is a common inhabitant of Southeast Asia's rice paddies, and the movement of migratory birds—a secondary carrier—could be predicted based on temperatures. So using both land-use and temperature information from satellites, Xiao and his team could track the spread of the flu by estimating where the birds would be.

If visual data from satellites is combined with information from radar and LiDAR, (light detecting and ranging, which provides laser-measured data about 3-D contours), Xiao explains, researchers can really hone prediction of some diseases down to a tree line. "You can look at… the transition of pasture grassland to forests," he says, habitats which determine the range of deer. "And this has very important implications for tick-borne diseases, like Lyme disease."

Much of the satellite work, however, still relies on clear skies. And all of it has been dependent on quality information from willing providers, such as NASA and its Earth Observing System, the availability of which researchers hope will continue in the future.

Even with the clearest NASA images, though, current methods are far from perfect. They employ complex models and incomplete information, risking false alarms and missed outbreaks.

The satellite data are still just a portion of the equation. They allow researchers to start "standing back and looking at the picture from a distance," Ford says. He and others are heavily reliant on ground-based measurements and observations. Xiao notes that, "the in situ observations are still very, very important. So the key is to combine those together—that's a real challenge."

3 Comments

1. 1. erichj 11:06 PM 8/24/09

   The SMAP , soil moisture mission, will see soil surface temps and soil moisture to 3 feet deep, Surface & Root zone soil moisture & Carbon Net Ecosystem Exchange
   http://smap.jpl.nasa.gov/mission/
   
   on the re-boot of the OCO (orbital carbon observer) to read the Carbon sources & Sinks from the tree tops down at 2 1/2 Acre resolution.
   
   A large enough array of other sensor technologies may allow zeroing in on particular GHG emissions, N2O & CH4 & CO2 by absorption lidar
   Mid-infrared laser absorption spectrometers /diode laser based detection of CO, N2O and NO.
   
   This seems to present a developing tool, along with other proxy measurements, for soil carbon.
   My hope is the common bond of Soil Carbon will lead to program synergy for Soil Carbon Sequestration. The unity of purpose between NASA, USDA, EPA, Academics,Ag Interests, etc. etc.should drive these programs from the inside out & the outside in.
   
   Agriculture allowed our cultural accent and Agriculture will now prevent our descent.
   Wise Land management, Organic farming and afforestation can build back our soil carbon,
   
   Remote sensor success would level the carbon credit playing field. No aggregaters, testers, heck, a farmer will just check his practices on Google earth with certain rewards for good behavior.
   
   Carbon to the Soil, the only ubiquitous and economic place to put it.
   Cheers,
   Erich
   
   

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2. 2. joef 01:05 PM 8/25/09

   It's a whole article about modeling and predicting diseases without mentioning the geospatial modeling aspect. No one is looking at a satellite image and identifying where diseases are, rather diseases, their environmental niches, and the pathways they travel by are identified and multiple data sources (remote sensing included) are used to predict possible outbreaks. The article seems to have been written using 'satellites' as the primary medium of focus because they are far more interesting to the lay-person then what is actually the primary driver of this work: spatial statistics. yuck.

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3. 3. H1N1 Specialist in reply to joef 06:53 PM 8/27/09

   Are you a loser? And you are wrong.

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