Muchiri E M, Ouma J H, King C H
Division of Vector Borne Diseases, Ministry of Health, Nairobi, Kenya.
Am J Trop Med Hyg. 1996 Nov;55(5 Suppl):127-34. doi: 10.4269/ajtmh.1996.55.127.
Ecologic modeling of Schistosoma transmission in endemic communities has suggested that antiparasite therapy targeted at the most heavily infected segment of the human population (i.e., school-age children) should have a significant impact on local parasite transmission. Our 1984-1991 experience with age-targeted therapy in the Msambweni area of Kenya has shown an overall decrease in area transmission within 1-2 years following initiation of annual treatment of school-age groups. Snail monitoring confirmed a continuing but variable reduction of vector infection rates. However, subgroup analysis showed significant differences in transmission suppression between more developed coastal villages with piped-water kiosks and villages with only limited access to safe water supplies. Villages without piped water were marked by higher initial prevalences of S. haematobium infection, greater prevalence among adults, longer and more frequent contact with high-risk water sources, and persistently high transmission despite compliance with parasitologic screening or drug therapy. We conclude that targeted therapy had a significant impact on S. haematobium transmission in some areas, but that more extensive or more prolonged coverage is necessary to reduce the rate of new infection in high-risk villages. Defining field-use algorithms, based on decision analysis of economic and ecologic parameters, should provide effective guidelines for selective versus mass treatment in expanded control areas.
血吸虫病流行社区传播的生态模型表明，针对人群中感染最严重部分（即学龄儿童）的抗寄生虫治疗应对当地寄生虫传播产生重大影响。我们1984年至1991年在肯尼亚姆桑布韦尼地区进行的针对特定年龄治疗的经验表明，在开始对学龄组进行年度治疗后的1至2年内，该地区的总体传播率有所下降。钉螺监测证实病媒感染率持续下降，但存在波动。然而，亚组分析显示，在拥有自来水亭的较发达沿海村庄和仅能有限获取安全水源的村庄之间，传播抑制存在显著差异。没有自来水的村庄的特点是，埃及血吸虫感染的初始患病率较高、成年人中的患病率更高、与高风险水源的接触时间更长且更频繁，并且尽管进行了寄生虫学筛查或药物治疗，传播率仍持续居高不下。我们得出结论，针对性治疗在某些地区对埃及血吸虫传播产生了重大影响，但需要更广泛或更长时间的覆盖范围，以降低高风险村庄的新感染率。基于经济和生态参数的决策分析来定义现场使用算法，应为扩大控制区域内的选择性治疗与群体治疗提供有效的指导方针。
