Duerr H P, Leary C C, Eichner M
Department of Medical Biometry, University of Tübingen, Westbahnhofstr. 55, 72070 Tübingen, Germany.
Int J Parasitol. 2006 Nov;36(13):1367-72. doi: 10.1016/j.ijpara.2006.08.001. Epub 2006 Aug 31.
Onchocerciasis has been successfully controlled for many years in endemic countries but more than 120 million people are still at risk. Factors which stabilise the persistence of the parasite in the population must be studied to minimise the future risk of re-infection. Among these factors, the relationship between the annual transmission potential and the parasite establishment rate is a main determinant which has to date not been quantified. Using entomological information and palpation data collected by the Onchocerciasis Control Programme in West Africa prior to the initiation of control activities, we derive annual transmission potential-dependent estimates of the parasite establishment rate from statistical analyses and computer simulations. Even at very low transmission intensities, the filarial parasite Onchocerca volvulus can efficiently establish in the human population, originating from an infection process which is strongly limited with respect to the annual transmission potential. Implementing the estimates into a simplified transmission model predicts that the critical annual biting rate, below which transmission is not possible, is much lower than previously assumed. We conclude that under the current strategy of mass distribution of microfilaricides without additional measures of vector control, the risk of re-infection is higher than previously assumed.
多年来，盘尾丝虫病在流行国家已得到成功控制，但仍有超过1.2亿人面临风险。必须研究使寄生虫在人群中持续存在的稳定因素，以尽量降低未来再次感染的风险。在这些因素中，年传播潜力与寄生虫定植率之间的关系是一个主要决定因素，迄今为止尚未进行量化。利用西非盘尾丝虫病控制计划在控制活动开始前收集的昆虫学信息和触诊数据，我们通过统计分析和计算机模拟得出了依赖于年传播潜力的寄生虫定植率估计值。即使在非常低的传播强度下，丝虫寄生虫盘尾丝虫也能在人群中有效定植，其感染过程在年传播潜力方面受到很大限制。将这些估计值应用于一个简化的传播模型预测，低于该值传播就不可能发生的临界年叮咬率比以前假设的要低得多。我们得出结论，在目前大规模分发微丝蚴杀虫剂而没有额外病媒控制措施的策略下，再次感染的风险比以前假设的要高。
