目平湖洲垸亚型疫区血吸虫病疫情纵向观察

Cohort study on endemic situation of schistosomiasis in an endemic village with embankment subtype in Muping Lake region, Hunan Province, China

目的观察洲垸亚型血吸虫病疫情纵向变化规律及影响因素。方法对观察点五一村居民病情、疫水接触史、家畜病情和螺情进行纵向观察。结果2002～ 2005年居民粪检阳性率分别为17．84％、11．44％、12．28％、12．05％。居民疫水暴露率、血吸虫感染率、感染度及再感染率，男性都高于女性，渔民及副业渔民明显高于其他职业人群。粪检阳性者化疗后一年内疫水暴露率93．44％，居民重复感染率为29．89％。2002～2005年耕牛粪检阳性率10．69％～17．50％。三峡建坝前（1993年）目平湖7～8月洪水期平均水位比建坝后的2002～2005年高1～2m，其他月份平均水位建坝后比建坝前高。五一外洲感染螺分布广泛，2003年春季钉螺感染率达0．90％，感染螺平均密度0．0263只／0．1m^2。2003～2005年钉螺调查，春季阳性钉螺密度及感染率明显高于秋季，活螺平均密度秋季明显高于春季。2006年春季调查未发现阳性钉螺。垸外草洲栽种欧美杨，当地耕牛存栏数量减少，由常年敞放改为轮值群放。结论该型疫区人、畜血吸虫感染率及再感染率高，垸外易感地带须因地制宜采取综合防治措施。

Objective To observe the dynamic changes of endemic situation of schistosomiasis in embankment subtype areas, and analyze its influential factors. Methods An endemic village （Wuyi） in enbankment subtype areas in Muping Lake of Dongting Lake region was selected and investigated. A cohort study was carried out for schistosomiasis prevalence and water contact history among human, and a longitudinal observation performed for schistosomiasis prevalence among domestic animals and snail distribution. Results From 2002 to 2005, the positive rates among the cohort population were 17.84%, 11.44%, 12. 28% and 12.05%, respectively, by Kato-Katz method. In terms of such indicators as the rate of water exposure, infection, re-infection, and intensity of schistosomiasis, the male were higher than the female, and fishermen by full or part time occupation were higher than other occupations, and 93. 44% of the infected residents had again contacted infectious water during the period of one year after chemotherapy, with 29.89% re-infection rate. From 2002 to 2005, the infection rates of schistosomiasis among cattle were fluctuated from 10.69% to 17.50% by hatching examination. The average water level from July to August （flood season）, 1993, when Three Gorges Reservoir had not established, was higher 1-2 m than that of 2002-2005, when the Reservoir was completed. However, the water levels in other months in those years were on the contrary. Snails on marshland outside Wuyi Village had extensive distribution. The infection rates of snails was 0. 90% and the average densities of infection snails was 0. 026 3/0. 1 m^2 in Spring of 2003. The infection rates of snails and the densities of infection snails in Spring of 2003-2005 were significantly higher than those in Autumn, vice versa for average densities of living snails. In 2006, infection snails were not detected. Italy poplars were planted around the marshland; natural grazing land was largely compressed and herds of local cattle pasturing was reduced. Uncontrollably pasturing habits of cattle herds were replaced by the controllably pasturing in turn. Conclusions Human and domestic animals have high infection and re-infection rates of schistosomiasis in this endemic area of embankment subtype. It is necessary to carry out the comprehensive measures according to the local conditions.