Filipe João A N, Boussinesq Michel, Renz Alfons, Collins Richard C, Vivas-Martinez Sarai, Grillet María-Eugenia, Little Mark P, Basáñez María-Gloria
Department of Infectious Disease Epidemiology, Imperial College London, Norfolk Place, London W2 1PG, United Kingdom.
Proc Natl Acad Sci U S A. 2005 Oct 18;102(42):15265-70. doi: 10.1073/pnas.0502659102. Epub 2005 Oct 10.
Here we analyze patterns of human infection with Onchocerca volvulus (the cause of river blindness) in different continents and ecologies. In contrast with some geohelminths and schistosome parasites whose worm burdens typically exhibit a humped pattern with host age, patterns of O. volvulus infection vary markedly with locality. To test the hypothesis that such differences are partly due to heterogeneity in exposure to vector bites, we develop an age- and sex-structured model for intensity of infection, with parasite regulation within humans and vectors. The model is fitted to microfilarial data from savannah villages of northern Cameroon, coffee fincas of central Guatemala, and forest-dwelling communities of southern Venezuela that were recorded before introducing ivermectin treatment. Estimates of transmission and infection loads are compared with entomological and epidemiological field data. Host age- and sex-heterogeneous exposure largely explains locale-specific infection patterns in onchocerciasis (whereas acquired protective immunity has been invoked for other helminth infections). The basic reproductive number, R0, ranges from 5 to 8, which is slightly above estimates for other helminth parasites but well below previously presented values.
在此，我们分析了不同大陆和生态环境中人体感染盘尾丝虫（致河盲症的病原体）的模式。与一些土源性蠕虫和血吸虫寄生虫不同，其虫负荷通常随宿主年龄呈现驼峰状模式，盘尾丝虫感染模式因地区而异。为检验这种差异部分归因于接触媒介叮咬的异质性这一假设，我们构建了一个年龄和性别结构的感染强度模型，该模型考虑了人体和媒介体内的寄生虫调节。该模型拟合了喀麦隆北部草原村庄、危地马拉中部咖啡种植园以及委内瑞拉南部森林居住社区在引入伊维菌素治疗前记录的微丝蚴数据。将传播和感染负荷的估计值与昆虫学和流行病学现场数据进行比较。宿主年龄和性别异质性暴露在很大程度上解释了盘尾丝虫病的地区特异性感染模式（而对于其他蠕虫感染则援引了获得性保护性免疫）。基本繁殖数R0范围为5至8，略高于其他蠕虫寄生虫的估计值，但远低于先前给出的值。
