- This image, made from NASA’s Terra satellite, shows the change in plant cover in the U.S. Southwest between June 2003-04. Yellow and red areas had lower green vegetation cover in 2004 relative to 2003. Blue areas had higher green vegetation cover in 2004 relative to 2003. Credit: Philip Dennison/University of Utah via Inside Science News Service
New research underscores how satellite imagery can be utilized to predict outbreaks of deadly diseases.
The key is to look for colors that change on photographs of the Earth’s surface, enabling scientists to deduce — months or even years ahead of time — when a disease might flare up and become a serious hazard.
The new research work has been published in the journal Global Ecology and Biogeography.
As example, biologist Denise Dearing of the University of Utah in Salt Lake City has lead a team to study hantavirus, an untreatable rodent-borne virus that has infected more than 560 people in the United States since it was discovered in 1993.
The researchers studied numerous satellite images of a test area in central Utah to understand variations in the amount of vegetation covering the Earth’s surface. After a rainy winter, more greenery popped up – a situation that creates more food for the mice, causing the critter population to increase. With more mice that meant more carriers of hantavirus coming into contact with humans.
By combining satellite imagery with data from thousands of mice captured over three years, the scientists found that a rise in vegetation led to a potentially illness-causing spike in the mouse population about 12 to 16 months later.
Malaria and cholera
“Satellite prediction is a very exciting approach, though it still needs more refinement,” said Tim Ford, a microbiologist at the University of New England in Biddeford, Maine, who studies water-borne illnesses. Any information from the sky, he added, must always be double-checked against conditions on the ground.
Ford has examined other diseases whose spread might be predicted from satellite images.
For malaria, public health officials could examine the amount and location of standing water where disease-carrying mosquitoes reproduce. For cholera, they could look at sea surface height and levels of the green pigment chlorophyll, because cholera bacteria spend much of their life attached to a floating animal that feeds on chlorophyll-filled plants.
Ford said there is even evidence that the spread of avian flu could be predicted from remote imaging, by mapping rice paddies and bird migration routes to identify potential hotspots for the disease.
Xiangming Xiao, a professor in the Center for Spatial Analysis at the University of Oklahoma in Norman has started testing the feasibility of tracking avian flu from satellites.
Remote tracking of disease will likely grow in the coming years, as images get sharper and data analysis gets more sophisticated.
“Satellite images will continue to play an increasing role in disease ecology and forecasting,” Xiao noted.
By LD/CSE