Plaisier A P, van Oortmarssen G J, Remme J, Alley E S, Habbema J D
Department of Public Health and Social Medicine, Medical Faculty, Erasmus University Rotterdam, Netherlands.
Bull World Health Organ. 1991;69(2):169-78.
Using a computer simulation study, we have investigated the risk and dynamics of onchocerciasis recrudescence after stopping vector control, in order to provide guidelines for operational decision-making in the Onchocerciasis Control Programme in West Africa (OCP). For this purpose, we used the microsimulation model ONCHOSIM to predict for periods of 9-15 years of vector control the ensuing risk and dynamics of recrudescence in an onchocerciasis focus. The model was quantified and validated using OCP evaluation and field research data. A range of plausible values was determined for important confounding parameters, i.e., vector biting rate, variation in exposure between individuals, parasite life span, and the relation between skin microfilarial load and vector infection. Different model quantifications were used in order to take account of the possible confounding effect of these parameters on the prediction of recrudescence. In the absence of immigration of infected humans or invasion by infected flies, the model predicts that 14 years of full-scale vector control are required to reduce the risk of recrudescence to less than 1%. The risk depends, in particular, on the vector biting rate, and this has implications for the planning of post-larviciding surveillance. Recrudescence will be a relatively slow process, and its rate will depend on the duration of vector control. Even if vector control were stopped too early, i.e., after 12-13 years in a highly endemic area, it would take more than 20 years before the intensity of infection in the community would reach levels of public health importance.
通过一项计算机模拟研究，我们调查了停止病媒控制后盘尾丝虫病复发的风险和动态变化，以便为西非盘尾丝虫病控制计划（OCP）中的业务决策提供指导方针。为此，我们使用微观模拟模型ONCHOSIM来预测9至15年病媒控制期后盘尾丝虫病疫源地复发的风险和动态变化。该模型使用OCP评估和实地研究数据进行了量化和验证。确定了一系列重要混杂参数的合理值，即病媒叮咬率、个体间暴露差异、寄生虫寿命以及皮肤微丝蚴负荷与病媒感染之间的关系。使用了不同的模型量化方法，以考虑这些参数对复发预测可能产生的混杂效应。在没有感染人类迁入或感染苍蝇入侵的情况下，该模型预测需要14年的全面病媒控制才能将复发风险降低至1%以下。风险尤其取决于病媒叮咬率，这对幼虫杀灭后监测的规划具有影响。复发将是一个相对缓慢的过程，其速度将取决于病媒控制的持续时间。即使病媒控制过早停止，即在高度流行地区12至13年后停止，社区感染强度要达到具有公共卫生重要性的水平也需要20多年的时间。
