Karanja Diana M S, Awino Emmy K, Wiegand Ryan E, Okoth Edward, Abudho Bernard O, Mwinzi Pauline N M, Montgomery Susan P, Secor W Evan
Neglected Tropical Diseases Branch, Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya.
Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, United States of America.
PLoS Negl Trop Dis. 2017 Oct 23;11(10):e0006033. doi: 10.1371/journal.pntd.0006033. eCollection 2017 Oct.
Mass drug administration (MDA) using praziquantel is the WHO-recommended approach for control of schistosomiasis. However, few studies have compared the impact of different schedules of MDA on the resultant infection levels. We wished to evaluate whether annual MDA was more effective than less frequent treatments for reducing community-level prevalence and intensity of Schistosoma mansoni infections.
We performed a cluster randomized trial (ISRCTN 14849830) of 3 different MDA frequencies over a 5 year period in 75 villages with moderate (10%-24%) initial prevalence of S. mansoni in school children in western Kenya. Praziquantel was distributed by school teachers to students either annually, the first 2 years, or every other year over a 4 year period. Prevalence and intensity of infection were measured by stool examination in 9-12 year old students using the Kato-Katz method at baseline, each treatment year, and for the final evaluation at year 5. S. mansoni prevalence and intensity were also measured in first year students at baseline and year 5.
Twenty-five schools were randomly assigned to each arm. S. mansoni prevalence and infection intensity in 9-12 year old students significantly decreased within each arm from baseline to year 5 but there were no differences between arms. There were no differences in infection levels in first year students either within or between arms.
Strategies employing 2 or 4 rounds of MDA had a similar impact in schools with moderate initial prevalence, suggesting that schistosomiasis control can be sustained by school-based MDA, even if provided only every other year.
使用吡喹酮进行群体药物治疗（MDA）是世界卫生组织推荐的控制血吸虫病的方法。然而，很少有研究比较不同MDA方案对最终感染水平的影响。我们希望评估年度MDA在降低社区层面曼氏血吸虫感染率和感染强度方面是否比不那么频繁的治疗更有效。
我们在肯尼亚西部75个村庄进行了一项整群随机试验（ISRCTN 14849830），在5年期间对3种不同的MDA频率进行了研究，这些村庄学龄儿童中曼氏血吸虫的初始感染率为中等水平（10%-24%）。吡喹酮由学校教师分发给学生，分发方式为：在前两年每年分发一次，或在4年期间每隔一年分发一次。在基线、每个治疗年份以及第5年进行最终评估时，使用加藤厚涂片法对9至12岁学生进行粪便检查，以测量感染率和感染强度。在基线和第5年时，还对一年级学生的曼氏血吸虫感染率和感染强度进行了测量。
每个组随机分配25所学校。从基线到第5年，每个组内9至12岁学生的曼氏血吸虫感染率和感染强度均显著下降，但各组之间没有差异。各组内和组间一年级学生的感染水平也没有差异。
在初始感染率中等的学校中，采用两轮或四轮MDA的策略具有相似的影响，这表明即使每隔一年进行一次基于学校的MDA，血吸虫病控制也可以持续。
