Watching Water from Space Could Aid Disease Prevention in China

Scientists are looking to outer space for help in their attempt to prevent new outbreaks of the tropical disease schistosomiasis in southern China.

Once the Three Gorges Dam is fully operational, researchers plan to use satellite data from space to determine whether changing water conditions in Poyang Lake, China’s largest freshwater lake, create favorable conditions for the snails associated with the chronic disease that can damage internal organs and impair growth and cognitive development in children.

Adult and juvenile snails living in stagnant tropical freshwater lakes and ponds serve as hosts during part of the life cycle of schistosomes, the family of parasite species that cause schistosomiasis infections in warm climates around the world.

The scientists hope to combine data on changing water levels with biological information about the snails’ behavior. This should help inform public health officials on ways to reduce schistosomiasis infection in the Poyang Lake region between the Three Gorges Dam and Shanghai.

“Really, the only prevention is to not touch the water,” said Motomu Ibaraki, an associate professor of earth sciences at Ohio State University and the leader of the research project. “What we hope we can do is point to the most dangerous areas for schistosomiasis transmission based on predictions we can calculate about the snail habitat.”

Ibaraki described the research at the American Geophysical Union annual meeting in San Francisco. The project represents an emerging field, combining the expertise of specialists in hydrology and infectious diseases to tackle public health problems, he said.

Schistosomiasis is the second-most prevalent tropical disease after malaria, affecting 200 million people worldwide, according to the National Institutes of Health. People are infected through contact with water contaminated with the parasite. The parasite burrows into human skin within seconds, eventually matures to adulthood and settles in various areas of the body.

Over time, the infection can lead to a variety of health complications, such as bladder cancer, kidney and liver damage, and blood infections. No vaccine is available to prevent the illness, and medications to treat it generally are not effective at breaking the disease cycle, especially in poor, developing areas of the world.

After infecting humans, the adult worms lay eggs, which are released into water sources through human waste, perpetuating the cycle of contamination. Tiny worms hatch from the eggs in the water, and use snails as an intermediate host until they’re large enough to float freely in the water.

The researchers traveled to the Poyang Lake region during the last two years to collect field data that they fed into a geographic information system documenting water levels, vegetation characteristics and air temperatures that, when combined, identify areas favorable for the host snails to thrive.