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Scientists Cite China's Success in Controlling 'Snail Fever'

Chinese researchers have developed a strategy that reduces the transmission of the parasitic illness schistosomiasis, which affects an estimated 207 million people in rural parts of Asia and Africa. Experts say drugs alone do not work very well to control the disease.

Chinese researchers are reporting in The New England Journal of Medicine that they have developed a strategy to reduce infections of the hard to control parasitic disease.

Experts say schistosomiasis can be a life-long illness that causes severe malnutrition and anemia. The infection occurs when human skin comes in contact with water contaminated with certain types of snails that carry schistosoma parasites.

The parasites live for a time in the snails, then release into the water, where they can penetrate human skin, invading the blood vessels and organs. When infected humans urinate or defecate into the water, eggs of the parasites go back into the environment, creating a vicious cycle.

Standard treatment for the parasitic disease is a drug called praziquantel.

But international health professor Charles King of Case Western Reserve University in Cleveland, Ohio says the drug is not enough to eliminate the disease from communities because schistosomiasis is a cyclical disease.

"You treat the infection today, but if it comes back next year, that person will go on and get into that vicious cycle of illness," he said. "So what they are reporting in this article is an attempt to go to a community and find out, 'Exactly what does it take to really stop transmission?' And I think that is a really exciting move forward in this particular field."

In their study, the researchers report the results of several measures taken to reduce the schistosomiasis infection rate from 2005 through 2007 in two Chinese villages in Jiangxi Province.

The measures include improving sanitation by providing fresh tap water to residents, building lavatories, providing boats with tanks to store human waste and an education campaign.

In one village, the infection rate dropped from 11.5 percent to 0.7 percent and the infection rate fell from four percent to less than one percent in the second village.

Dr. King says slowing the cycle of infection, as the Chinese researchers showed, can have long-term benefits for impoverished villages where residents are stricken with schistosomiasis.

"We would expect to see a boost in health, what they call a 'virtuous cycle,' that all those improvements would feed into the community and help to improve their development," he said. "And that would actually facilitate changes that we need."

Dr. King wrote an editorial applauding the study led by the China Ministry of Health's Dr. Long-De Wang, that was published in this week's edition of The New England Journal of Medicine.