RÉSUMÉ
Objective To understand the dynamic rules of schistosomiasis endemic situation before and after reaching the criteria of schistosomiasis transmission controlled or transmission interrupted,so as to provide the evidence for improving schis-tosomiasis control. Methods Wuling District,Xihu District and Linli County were selected and investigated retrospectively to collect the schistosomiasis epidemiological information 10 years before they reached the criteria of transmission controlled and the subsequent years until 2008. A database of retrospective investigation was established for analyzing the trends and rules of changes of the Oncomelania hupensis snail status and infection status of cattle and human. Results In Wuling District,the en-demic situation was declining,and no schistosome infection persons,animals and snails were found after 1974. There was no re-bound until 2008. In Xihu District,the endemic situation reached the criteria of transmission controlled in 1997,and the endem-ic situation was stable. The human infection rate was positively correlated with the area of infection snails(r=0.584,P<0.05). In Linli County,there were no snails,no infected persons and cattle twice,but 2 endemic rebounds,and there were positive corre-lations between the densities of living snails and the infection rates of human and animal during the endemic rebound period. Conclusion The snail status is an important indicator of schistosomiasis endemic rebound. Therefore,the snail control is one of the most important schistosomiasis control measures.