血吸虫病控制新策略的研究

A new strategy to control transmission of Schistosoma japonicum

目的:我国血吸虫病的传播与自然生态环境和社会经济等因素关系密切,采取以前的防治策略难以控制湖沼型血吸虫病的传播。研究旨在探索以控制传染源为主的湖沼型血吸虫病流行区综合防治新策略的效果。方法:选取了江西省鄱阳湖地区、每年常规实施化疗防治措施的2个干预村和2个对照村进行现场研究。新的干预措施于2005年全面实施,主要措施包括封洲禁牧、"以机代牛"、改水改厕、渔船民粪便管理等措施,并强化健康教育措施,以降低人和耕牛作为钉螺传染源的作用。并于2005—2008年间连续观测了人群感染率、钉螺感染率以及哨鼠感染率的变化情况。结果:干预措施实施后,经3个传播季节后干预组的血吸虫人群感染率降到1.0%以下,其中爱国村从11.3%降到0.7%,新和村从4.0%降到0.9%(两两比较均P<0.001),且在第4个传播季节后分别持续下降至0.2%和0%。而对照组人群感染率出现上下波动,但仍维持在原来的基线水平。干预组一个草洲上的感染性钉螺密度在4个传播季节后分别从2.2%和0.3%下降到0%(两两比较均P<0.01),而暴露于水体中的哨鼠感染率从79.3%降至0%(P<0.001)。结论:以传染源控制为主综合性防治策略能有效地降低日本血吸虫病在耕牛、人群和钉螺间的传播,这一策略现已被采纳为中国新的血吸虫病防治策略。

Objective： To evaluate an integrated strategy for the national program on schistosomiasis control with emphasis on eliminating transmission of Schistosoma japonicum in marsh and lake region, since it is of difficulty to control the transmission of S. japonicum by using previous strategies in the region with the changes of environmental and social context in China. Methods： a comprehensive control strategy was evaluated in two intervention villages and two control villages along Poyang Lake in southeast of Jiangxi Province, where annual synchronous chemotherapy is routinely used. New interventions, implemented from 2005 through 2007, included removing cattle from snail-infested grasslands, providing farmers with mechanized farm equipment, improving sanitation by supplying tap water and building lavatories and latrines, providing boats with fecal,matter containers, and implementing an intensive health-education program. During the intervention period, changes were observed in S. japonicum infection in humans, measured the rate of infection in snails, and tested the infectivity of lake water in mice. Results After three transmission seasons, the rate of infection in humans decreased to less than 1.0 % in the intervention villages, from 11.3 % to 0.7 % in one village and from 4.0 % to 0.9 % in the other （P 〈0.001 for both comparisons）. And the rate of infection in humans sustainably decreased to 0.2 % and 0 % after the fourth transmission seasons. The rate of infection in humans in control villages fluctuated but remained at baseline levels. In intervention villages, after four transmission seasons, the percentage of sampling sites with infected snails decreased from 2.2 % and 0.3 % to no infection in two marshlands, respectively （ P 〈 0.001 for both comparisons）. The rate of infection in mice after exposure to lake water decreased from 79 % to no infection （ P 〈 0. 001 ）. Conclusions： A comprehensive control strategy based on interventions to reduce the rate of transmission of S. japonicum infection from cattle and humans to snails was highly effective. These interventions have been adopted as the national strategy to control schistosomiasis in China.