ABSTRACT
Objective To explore the potential key risk factors of schistosomiasis transmission in potential endemic areas so as to provide the evidence for setting up the prediction and surveillance systems of schistosomiasis outbreak epidemic. Methods From 2008 to 2012,fixed and mobile surveillance sites in potential endemic areas of 2 counties in Hubei Province were selected. The immunological assays and stool examinations were carried out to investigate the schistosome infection situation of local people, mobile population and livestock. The distribution of Oncomelania hupensis snails was investigated in risk areas and suspicious ar-eas,and spreading patterns of snails were observed in the rivers that directly connected with the Yangtze River. Results A total of 6 052 local people aged 6-65 years were screened by IHA immunological tests,and the positive rate of antibody was 1.19%(72/6 052). Totally 72 antibody positives were examined by Kato-Katz technique and there were no positives. A total of 5 004 mo-bile persons were tested by IHA immunological tests and the positive rate was 1.36%(68/5 004). Totally 68 antibody positives were examined by Kato-Katz technique and there were no positives. Totally 287.07 hm2 potential endemic areas were investigated for Oncomelania snail detection,and no snails were found. The investigation on snail spreading patterns and the surveillance on suspicious circumstances were carried out,with no snails found. Conclusions In the schistosomiasis potential endemic areas, some positives of IHA immunological tests are found. Therefore,monitoring is still needed to be strengthened.
ABSTRACT
Objective To compare the molluscicidal effects between“Luo-wei”(TDS),a plant molluscicide in 4 percent, and metaldehyde and niclosamide(MNSC)in the field. Methods A natural ecological environment with Oncomelania hupensis was selected as the test area,the test concentrations of TDS and MNSC were 2.5 g/m3 and 2 ml/m3 respectively by the immersion method;the test doses of TDS and MNSC were 3 g/m2 and 2 ml/m2 respectively by the spray method;the doses of WPN in a control group were 2 g/m3 and 2 g/m2 respectively by the two methods above-mentioned. The molluscicidal effects between TDS and MNSC were compared by using the synchronous design method and parallel comparative method. Results In the TDS group,the death rate of snails was 90.70%by immersion for 24 hours,reached to 81.40%after spraying for 7 days,and there were no significant differences among the observation time points in molluscicidal effects(P>0.05). One day after the spraying,the death rate of snails was less in the TDS group compared with that in the MSCN group(P0.05). In the MSCN group,the death rate of snails was 99.17%by immersion for 24 hours,reached to 66.07% by spraying for 1 day. In the WPS group,the death rate of snails was 97.15% by immersion for 24 hours,reached to 71.43%after spraying for 1 day,and there were no significant differences(both P>0.05). Conclusion TDS has a good molluscicidal activity and stable efficacy,and the molluscicidal effect of TDS is similar to that of MSCN in the filed, but the molluscicidal sensitivity of TDS is lower than that of MSCN.
ABSTRACT
Objective To understand the dynamic changes of snail situation and wild faeces pollution in marshlands in the pilot areas after leveling embankment for flood running and moving people from outside embankment to town for providing the scientific basis of schistosomiasis control in the same type areas. Methods Shishou City,Jiangxia District,Tuanfeng County and Huangzhou District were selected as the pilot areas. Snails were surveyed by the systematic and environmental sampling. Wild faeces were also investigated. The data were processed by Excel. Results Snail areas in Huangzhou Yeluzhou increased by 12.71%,in the others it did not change. For the snail density,there was a decline trend in Jiangxia Sanjiaozhou from 1999 to 2001,but it increased in 2002 obviously;in Huangzhou Yeluzhou it decreased in 2000,but increased again from 2001 to 2002;in Tuanfeng Luohuozhou it was fluctuation;it did not change in Shishou Fuxingzhou. Except Shishou City,the other three sites had infected snails distribution. The densities of wild faeces in the pilot areas were 1.14～15.60/hm~2. The positive rates of wild faeces were 1.35%～37.21%. Conclusion The marshlands in pilot areas were seriously polluted by wild faeces. There seemed to be an increase trend in the snail density. Snail areas did not change significantly in the last few years. However,the high transmission areas will expand. So the snail survey and snail control should be strengthened.
ABSTRACT
Zishi township of Jiangling city is located in the canal area inside embankment,a heavy endemic area of schistosomiasis japonica in Hubei province. The population and cattle preva-lence was 29.5% and 66.7% respectively in 1992. There are 66 canals and it covered a total area of 300000m2. 97.0% of the canals and 99.3% of the total area had snail inhabitants, and 7.6% of the snails distributed in canal was infected which covered 18.3% of the total area. The snails were mainly distributed in the main canal and their branches. The rate of snail distribution was 45.2% and 39.8% respectively. Cattle was pastured all year round in this area. Examination of scattered cattle feces and water revealed that the major factor of water contamination was scattered cattle feces. It explained why the infection rate of snail was high and the distribution of infected snail was extensive and how the major high rise area inside embankment was formed.