[Surveillance of schistosomiasis in a national surveillance site, Nanzhong Village, Nanjing City, 2010-2011].

OBJECTIVE: To understand the dynamic of schistosomiasis epidemic situation in a national surveillance site, Nanzhong Village, Qixia District, Nanjing City, 2010-2011, so as to provide the evidence for evaluating the control effect and formulating prevention countermeasures. METHODS: According to the National Schistosomiasis Monitoring Program, the Oncomelania snail status and the situation of endemic schistosomiasis were surveyed and the data were analyzed statistically. RESULTS: The emergence rate of frames with living Oncomelania snails decreased by 11.67% and the average density of living snails decreased by 95.49% in 2011 compared to those in 2010. No infected snail was found during the past 2 years. The infection rate of schistosome in the permernant residents decreased from 9.93% (95/957) in 2010 to 1.35% (7/519) in 2011, and no acute schistosomiasis case was found. All the stool tests of schistosome infection in domestic animals were negative. CONCLUSIONS: The schistosomiasis epidemic situation shows a decline trend year by year which demonstrates the routine comprehensive control measures are effective. However, the snail habitat area has not decreased significantly. Therefore, we should strengthen the snail control and continue the surveillance of snail status and infectious sources of schistosomiasis.

[Snail control effect of film covering method in fish ponds and ditches].

OBJECTIVE: To evaluate the snail control effect of a film covering method in fish ponds and ditches. METHODS: Two fish ponds and 2 ditches with Oncomelania snails were selected as pilots, and 1 fish pond as Group A1 and I ditch as Group B1 received niclosamide spraying + film covering, and another fish pond as Group A2 and another ditch as Group B2 received niclosamide spraying only. The snail control effects were observed at 15, 30, 90 d and 360 d after the test, and the fish and other aquatic were also observed. RESULTS: In Group A1, the adjusted mortality rates of snails were 92.31%, 99.36% and 100% at 15, 30 d and 90 d after the test, respectively; in Group B1, the adjusted mortality rates of snails were 91.45%, 95.84% and 100% at 15, 30 d and 90 d after the test, respectively; and there was no death of fish. The densities of snails were 0 and 0.07 snails/0.1 m2 one year after the test, respectively. In Group A2, the adjusted mortality rates of snails were 75.36%, 72.59% and 65.76% at 15 d, 30 d and 90 d after the test, respectively; in Group B2, the adjusted mortality rates of snails were 70.36%, 72.87% and 75.82% at 15, 30 d and 90 d after the test, respectively; and there was death of fish. The densities of snails were 0.11 snails/0.1 m2 and 0.13 snails/0.1 m2 one year after the test, respectively. CONCLUSION: In ponds and ditches with snails, the niclosamide spraying + film covering method is very effective and safe.