[Surveillance and forecast of schistosomiasis transmission in Chaohu Lake area in Anhui Province, 2008-2010].

OBJECTIVE: To understand the dynamic changes of the potential prevalent factors of schistosomiasis in Chaohu Lake area so as to provide forecast information on the outbreak of schistosomiasis in the area. METHODS: From 2008 to 2010, fixed and mobile surveillance sites in potential endemic areas of Juchao District in Chaohu City, which was located in the southeast side of Chaohu Lake, were selected, and the schistosomiasis infection situation of local people, mobile population and livestock were investigated by immunological assays and/or stool examinations. The distribution of Oncomelania snails was surveyed in risk areas and suspicious areas, the spreading patterns of Oncomelania snails were observed in rivers that directly connected with the Yangtze River, and the Oncomelania snails were raised in the cages on the beaches of Chaohu Lake and a control area, and their survival and reproduction capacity was observed. RESULTS: In 2008, a total of 301 local people were screened by IHA, and there were no positives. From 2008 to 2010, a total of 321, 362 and 306 mobile population were examined by IHA, respectively, and the positive rate of antibody were 3.74%, 4.97% and 2.94%, respectively. The antibody positives were tested by stool examinations, and the positive rates were 66.67%, 50% and 55.56%, respectively. A total of 91 local livestock and 92 livestock from endemic areas were examined respectively by the miracidium hatching method, and there were no positives. A total of 97.8 hm2 risk areas and 193.62 hm2 suspicious areas in the potential endemic area were surveyed respectively, but no Oncomelania snails were found. The investigation results on snail spreading patterns indicated that snails could spread into Chaohu Lake by adsorbing on floating debris. The field study revealed that Oncomelania snails could survive and reproduce in the Lake. CONCLUSIONS: The imported infectious sources of schistosomiasis have been found in Chaohu Lake area, and the higher possibility of imported Oncomelania snails spreading into the Lake and surviving and reproducing in the lake is predicted. Therefore, effective measures should be taken to decrease the risks of schistosomiasis transmission in the potential endemic area.