Chippaux J P, Bouchité B, Boussinesq M, Ranque S, Baldet T, Demanou M
Antenne ORSTOM auprès du Centre Pasteur du Cameroun, Yaoundé, Cameroon.
Trans R Soc Trop Med Hyg. 1998 Jul-Aug;92(4):454-8. doi: 10.1016/s0035-9203(98)91091-4.
We have studied the impact of large-scale treatment with ivermectin on the transmission of loiasis in a forest village in south Cameroon where loiasis was highly endemic, with a prevalence of 30%. After one year of parasitological and entomological surveillance without treatment, all consenting residents aged > 5 years received ivermectin 200 micrograms/kg every 3 months. For ethical reasons, treatment was interrupted after 2 years, but parasitological and entomological surveillance continued for 18 months after the end of treatment. The prevalence of loiasis was reduced to < 10% and the mean microfilaraemia decreased by 90% in 2 years. The prevalence and average intensity of infection remained stable during the 18 months after treatment ended. Two vector species were identified, Chrysops dimidiata (representing about 90% of the fly population) and C. silacea. The infection rate (all stages) in Chrysops decreased by 75% and the infective rate (percentage of Chrysops harbouring third-stage larvae of Loa loa in the head) decreased by 85% in C. dimidiata and became zero in C. silacea. After the end of treatment, the infection and infective rates increased gradually. Large-scale treatment seemed an efficient method for the control of L. loa transmission provided high drug coverage was achieved. Nevertheless, because of the high risk of adverse effects when using the current microfilaricidal drugs, such a strategy remains unacceptable.
我们研究了在喀麦隆南部一个森林村庄大规模使用伊维菌素治疗对罗阿丝虫病传播的影响。该村庄罗阿丝虫病高度流行，患病率为30%。在未经治疗进行了一年的寄生虫学和昆虫学监测后，所有年龄大于5岁且同意参与的居民每3个月接受200微克/千克的伊维菌素治疗。出于伦理原因，2年后治疗中断，但在治疗结束后寄生虫学和昆虫学监测又持续了18个月。2年内，罗阿丝虫病的患病率降至<10%，平均微丝蚴血症下降了90%。治疗结束后的18个月内，感染的患病率和平均强度保持稳定。鉴定出两种传播媒介，即半翅斑虻（占蝇类种群的约90%）和静斑虻。半翅斑虻的感染率（各阶段）下降了75%，感染性率（头部带有罗阿丝虫第三期幼虫的半翅斑虻百分比）在半翅斑虻中下降了85%，在静斑虻中降为零。治疗结束后，感染率和感染性率逐渐上升。如果能实现高药物覆盖率，大规模治疗似乎是控制罗阿丝虫传播的有效方法。然而，由于使用当前的杀微丝蚴药物时出现不良反应的风险很高，这种策略仍然不可接受。
