Effect of Poplar Forest on Snail Control in Dongting Lake Area

Schistosomiasis is a parasitic infection caused by blood flukes (trematodes) of the genus Schistosoma. The intermediate host is an aquatic or amphibious snail (Oncamelania hupensis) . The World Health Organization describes schistosomiasis as ´the second most important (tropical disease) in terms of public health importance´ after malaria. It is endemic in 76 developing countries, putting over 600 million people at risk of infection. Over 200 million people are estimated to be infected worldwide, with 20,000 deaths annually. Officials detected 10.58 million square meters of new snail habitats in 2005, up 0.44 percent over 2004 when China had 3.85 billion square meters of snail habitats, according to figures from the Ministry of Health. To be effective, schistosomiasis control strategies should be adapted to the local epidemiological situation and caution must be taken when destroying freshwater snails using chemicals - particularly in terms of impact on the environment. One of the effective practices in China is conducting forestry ecological engineering that focuses on snail control and schistosomiasis prevention through improving environment and refraining snail propagation. Test plot located at Dongting Lake, Hunan province, where usually was most endemic areas. Poplars were planted according to the certain designs, site preparation was done to wipe out weeds and pile up ridges, spacing was 6 m times 8 m, and undisturbed site was as the check. After 12 years, the results indicated that snail density was decreased 85.2%--100% in poplar stands; while for the check, the figure was increased 108.2%--120%, and particularly no infected snail were found in poplar stands. With tree growing up, the number of snails fell. As well, poplars growing added incomes for local farmers. By the experiment, it was concluded that improving environment to reduce the amount of snail was available through forestation in wet beach areas.