Tracking disease from outer space

Feb 24, 2011 By Katharine Gammon
This satellite image uses an index of plant cover in June 2004 in the U.S. Four Corners region of Utah, Colorado, New Mexico and Arizona. Lighter, brighter greens indicate a greater amount of green plant cover. Credit: Philip Dennison, University of Utah

Satellite images are great for creating maps, finding bad guys, and, it turns out, predicting when deadly illnesses may break out.

By watching colors change on photographs of the Earth's surface, scientists can figure out, months or even years ahead of time, when a disease might flare up and become a serious hazard.

Traditional methods for following the spread of disease are hard work, according to biologist Denise Dearing of the University of Utah in Salt Lake City. She studies hantavirus, an untreatable rodent-borne virus that has infected more than 560 people in the United States since it was discovered in 1993. It's fatal in about half the cases. To keep tabs on the disease, "we had been going out and surveying mouse populations," Dearing said. But catching the mice, testing their blood, and microchipping them for future reference was difficult and time-consuming.

In 2004, Dearing's team of biologists began working with geographers on a high-tech way to track mice. The researchers studied numerous of their 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 -- creating more food for the mice and causing the critter population to increase. And more mice meant more carriers of hantavirus coming into contact with humans.

Their study, published last week in the journal Global Ecology and Biogeography, combined 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.

The power to predict could be tremendously useful, said Tim Ford, a microbiologist at the University of New England in Biddeford, Maine, who studies water-borne illnesses.

"Satellite prediction is a very exciting approach, though it still needs more refinement," Ford said, adding that any information from the sky 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.

The 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

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.

Advance warning of an outbreak can be a matter of life and death. Ford's research shows that if health officials know that a cholera outbreak might be coming, they can encourage people to take simple precautions like filtering drinking water through a cloth, which can reduce mortality by 50 percent. In the case of hantavirus, people in areas where mouse populations spiked in 2005 and 2006 were warned to avoid sweeping out barns -- the virus typically infects humans when they breathe in tiny particles that spread into the air from mouse droppings.

Still, there are challenges to making sense of all the images from above. "Some of the limitations are problems like cloud coverage changes over time [and] spatial and temporal resolutions," as well as insufficient understanding of the relationship between habitats and the animals that carry disease, said Xiangming Xiao, a professor in the Center for Spatial Analysis at the University of Oklahoma in Norman. Xiao 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 ecology and forecasting," said Xiao.

Explore further: How Australia got the hump with one million feral camels

More information:

Provided by Inside Science News Service

5 /5 (1 vote)

Related Stories

Monitoring killer mice from space

Feb 15, 2011

The risk of deadly hantavirus outbreaks in people can be predicted months ahead of time by using satellite images to monitor surges in vegetation that boost mouse populations, a University of Utah study says. ...

Remote sensing used to track humanity

Jul 06, 2006

A U.S. geography professor is using satellite imagery to determine how land use and land cover changes affect human health and food security.

Big, old mice spread hantavirus

Jan 07, 2009

University of Utah researchers dusted wild deer mice with fluorescent pink, blue, green, yellow and orange talcum powders to show which rodents most often fought or mated with others and thus were most likely ...

Hantavirus found in African wood mouse

Apr 18, 2006

Scientists have reported the discovery of the first African hantavirus, a type of rodent-borne virus that can cause life-threatening infections in humans.

UNH research uses satellite observation to track avian flu

Nov 20, 2006

An international, interdisciplinary team of researchers led by professor Xiangming Xiao of the University of New Hampshire is taking a novel scientific approach in an attempt to understand the ecology of the avian influenza, ...

Recommended for you

Researchers detail newly discovered deer migration

5 hours ago

A team of researchers including University of Wyoming scientists has documented the longest migration of mule deer ever recorded, the latest development in an initiative to understand and conserve ungulate ...

How Australia got the hump with one million feral camels

5 hours ago

A new study by a University of Exeter researcher has shed light on how an estimated one million-strong population of wild camels thriving in Australia's remote outback have become reviled as pests and culled ...

Former Iron Curtain still barrier for deer

11 hours ago

The Iron Curtain was traced by an electrified barbed-wire fence that isolated the communist world from the West. It was an impenetrable Cold War barrier—and for some inhabitants of the Czech Republic it ...

Humpback protections downgrade clears way for pipeline

21 hours ago

Environmentalist activists on Tuesday decried Canada's downgrading of humpback whale protections, suggesting the decision was fast-tracked to clear a major hurdle to constructing a pipeline to the Pacific ...

Maine baby lobster decline could end high catches

21 hours ago

Scientists say the number of baby lobsters settling off the rocky coast of Maine continues to steadily decline—possibly foreshadowing an end to the recent record catches that have boosted New England's lobster fishery.

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

not rated yet Feb 25, 2011
what is the point of technology that tracks a disease if no one is going to help kill the disease
not rated yet Feb 25, 2011
If you're interested in more research that the University of Utah is doing, Follow us on Twitter and Facebook!

Twitter: UofUResearch
Facebook: Find A Researcher

More news stories