Kariuki Henry C, Madsen Henry, Ouma John H, Butterworth Anthony E, Dunne David W, Booth Mark, Kimani Gachuhi, Mwatha Joseph K, Muchiri Eric, Vennervald Birgitte J
Parasit Vectors. 2013 Apr 18;6:107. doi: 10.1186/1756-3305-6-107.
Schistosoma mansoni infection is a persistent public health problem in many Kenyan communities. Although praziquantel is available, re-infection after chemotherapy treatment is inevitable, especially among children. Chemotherapy followed by intermittent mollusciciding of habitats of Biomphalaria pfeifferi, the intermediate host snail, may have longer term benefits, especially if timed to coincide with natural fluctuations in snail populations.
In this cohort study, the Kambu River (Intervention area) was molluscicided intermittently for 4 years, after mass chemotherapy with praziquantel in the adjacent community of Darajani in January 1997. The nearby Thange River was selected as a control (Non-intervention area), and its adjacent community of Ulilinzi was treated with praziquantel in December 1996. Snail numbers were recorded monthly at 9-10 sites along each river, while rainfall data were collected monthly, and annual parasitological surveys were undertaken in each village. The mollusciciding protocol was adapted to local conditions, and simplified to improve prospects for widespread application.
After the initial reduction in prevalence attributable to chemotherapy, there was a gradual increase in the prevalence and intensity of infection in the non-intervention area, and significantly lower levels of re-infection amongst inhabitants of the intervention area. Incidence ratio between areas adjusted for age and gender at the first follow-up survey, 5 weeks after treatment in the non-intervention area and 4 months after treatment in the intervention area was not significant (few people turned positive), while during the following 4 annual surveys these ratios were 0.58 (0.39-0.85), 0.33 (0.18-0.60), 0.14 (0.09-0.21) and 0.45 (0.26-0.75), respectively. Snail numbers were consistently low in the intervention area as a result of the mollusciciding. Following termination of the mollusciciding at the end of 2000, snail populations and infections in snails increased again in the intervention area.
The results of this study demonstrate that in the Kenyan setting a combination of chemotherapy followed by intermittent mollusciciding can have longer term benefits than chemotherapy alone.
曼氏血吸虫感染在肯尼亚许多社区仍是一个持续存在的公共卫生问题。尽管有吡喹酮可用，但化疗后再次感染难以避免，尤其是在儿童中。化疗后间歇性杀灭中间宿主蜗牛——费氏双脐螺的栖息地，可能会带来更长期的益处，特别是如果时机与蜗牛种群的自然波动相吻合。
在这项队列研究中，1997年1月在相邻的达拉贾尼社区用吡喹酮进行大规模化疗后，坎布河（干预区）间歇性地进行了4年的杀螺处理。附近的坦格河被选为对照（非干预区），其相邻的乌利林齐社区于1996年12月接受了吡喹酮治疗。每月在每条河沿岸的9 - 10个地点记录蜗牛数量，同时每月收集降雨数据，并在每个村庄进行年度寄生虫学调查。杀螺方案根据当地情况进行了调整，并进行了简化以提高广泛应用的前景。
在化疗导致患病率初步下降后，非干预区的感染率和感染强度逐渐上升，而干预区居民的再次感染水平显著较低。在非干预区治疗后5周和干预区治疗后4个月的首次随访调查中，经年龄和性别调整后的地区发病率比值无显著差异（很少有人转为阳性），而在随后的4次年度调查中，这些比值分别为0.58（0.39 - 0.85）、0.33（0.18 - 0.60）、0.1（0.09 - 0.21）和0.45（0.）。由于杀螺处理，干预区的蜗牛数量一直较低。2000年底杀螺处理终止后，干预区的蜗牛种群和蜗牛感染情况再次增加。
本研究结果表明，在肯尼亚的环境中，化疗后间歇性杀螺相结合比单纯化疗具有更长期的益处。
