黄石水库灌溉系统血吸虫病新流行区形成及防制研究

STUDY ON FORMATIVE FACTORS ATTRIBUTABLE TO A NEWLY ENDEMIC AREA OF SCHISTOSOMIASIS AND CONTROL STRATEGIES WITHIN THE RANGE OF IRRIGATION SYSTEM FROM HUANGSHI RESERVOIR

目的 探讨水库灌溉系统血吸虫病新流行区的形成因素与防制对策。方法 通过现场调查结合访问、座谈、查阅历史资料 ,了解钉螺和传染源来源情况。选择有代表性且疫情较重的 2个自然村 ,采取化疗消除传染源为主结合重点灭螺的综合防制对策。结果 历史上可能有未发现的少量钉螺存在 ,通过 6 0年代修建黄石水库 ,钉螺进入灌溉渠道大量扩散 ,在输入外来传染源后 ,导致了血吸虫病新流行区的形成和扩大。试区采取上述防制对策后 ,居民血吸虫感染率由 1998年的 12 .16 %下降到 2 0 0 0年的 0 .14% ,下降了 98.8% ;耕牛感染率由 15 .91%下降到 1.35 % ,下降了 91.2 % ;活螺密度由 9.12 %只 /框 (每框 0 .1m2 ,下同 ) ,下降到 0 .11只 /框 ,下降了 98.8% ;感染螺密度由0 .0 2 48只 /框 ,下降到 0。 1999年和 2 0 0 0年均未查到感染螺。结论 修建水库 ,如有钉螺进入灌溉系统 ,可以沿水系造成大面积扩散 ,加之传染源输入而形成新的血吸虫病流行区。采取以消除传染源为主结合重点灭螺的综合防制对策 。

ObjectiveTo identify the formative factors attributable to a newly endemic area of schistosomiasis and develop control strategies within the range of reservoir irrigation system. ]Methods Field investigation in conjunction with interview with leading subjects, examination of historical records were conducted to explore the origination of vectors and infection sources. Two villages with considerable endemicity and typical local epidemical characteristics were chosen as the pilots. The extensive chemotherapy as the chief control strategy to eliminate the infection sources combined with focus mollusciciding were undertaken. [WT5”HZ]Results [WT5”BZ]It was believed that there were a small number of historical residual snails which had been missing to be found in localities. As Huangshi Reservoir had been constructed in 1960s, aforementioned sources of snail were introduced to and diffused along the irrigation system. With the advent of exotic infection sources of schistosomiasis, the newly endemic area was formed and developed. After the aforementioned measures were carried out, the infection rate of inhabitants was reduced from 12. 16% in 1998 to 0 14% in 2000, reduced by 98 8%; and from 15 91% in 1998 to 1 35% in 2000 and reduced by 91 2% for cattle Meanwhile, the density fo living snails had reduced from 9 12/0 1m 2 to 0 11/0 1 m 2, reduced by 98 8%; and reduced from 0 0248/0 1 m 2 to 0 for infected snails No infected snails were detected in 1999 and in 2000 [WT5”HZ]Conclusion [WT5”BZ]The construction of reservoir, in case of sources of snails, couldcause snails to diffuse on a large scale along its irrigation system. Newly endemic areas for schisto somiasis could be formed when the sources of infection were introduced. Transmission of schistosomiasis could be interrupted by means of strategy dominated by extensive chemotherapy plus focus mollusciciding.