Unité Mixte de Recherche 145, Institut de Recherche pour le Développement and University of Montpellier 1, 911 Avenue Agropolis, BP 64501, 34394 Montpellier Cedex 5, France.
Acta Trop. 2011 Sep;120 Suppl 1:S91-9. doi: 10.1016/j.actatropica.2010.05.004. Epub 2010 May 24.
Reduction in Onchocerca volvulus skin microfilarial densities after treatment with ivermectin shows wide between-host variation. Data from two separate studies conducted in Cameroon on onchocerciasis patients treated for the first time with ivermectin were analyzed to identify host factors associated with microfilarial density at different time-points after treatment. In one site (Nkam valley), the dataset included 103 adult males for whom age, number of palpable onchocercal nodules and microfilarial densities on D0 (pre-treatment), D15, D80 and D180 were available. In the other site (Vina valley), analyses were conducted on 965 individuals of both sexes aged 5 years and over; in this dataset, available information included age, gender, exact dose of ivermectin received, onchocerciasis endemicity level in the village of residence and microfilarial densities on D0 and D180. Negative binomial regression models of microfilarial density at the different intervals post-treatment were fitted, using maximum likelihood, with the available independent variables. Gender and age were found to be associated with microfilarial density on D180. The initial microfilarial density influenced post-treatment densities at all the time-points. All other things being equal, microfilarial densities on D180 were higher in individuals harbouring a higher number of nodules or living in communities with high endemicity levels. This study demonstrates that O. volvulus microfilarial density measured after a first treatment with ivermectin, and thus probably the rate of skin repopulation by microfilariae (mf) varies according to several host factors. Should such factors also influence ivermectin efficacy after repeated treatment, then they should be taken into account to determine whether sub-optimal responses to treatment reported from various areas in Africa are actually due to parasite-related factors, particularly to the emergence of resistant populations.
在接受伊维菌素治疗后，盘尾丝虫皮肤微丝蚴密度降低，显示出宿主间广泛的变异性。对在喀麦隆首次接受伊维菌素治疗的盘尾丝虫病患者进行的两项独立研究的数据进行了分析，以确定与治疗后不同时间点微丝蚴密度相关的宿主因素。在一个地点（Nkam 河谷），数据集包括 103 名成年男性，他们的年龄、可触及的盘尾丝虫结节数量和治疗前（D0）、D15、D80 和 D180 的微丝蚴密度均可用。在另一个地点（Vina 河谷），对 965 名年龄在 5 岁及以上的男女进行了分析；在这个数据集中，可用的信息包括年龄、性别、实际接受的伊维菌素剂量、居住村庄的盘尾丝虫病流行程度以及 D0 和 D180 的微丝蚴密度。使用最大似然法拟合了不同间隔时间点微丝蚴密度的负二项回归模型，并使用了可用的独立变量。发现性别和年龄与 D180 的微丝蚴密度相关。初始微丝蚴密度影响所有时间点的治疗后密度。在其他条件相同的情况下，在携带更多结节的个体或生活在高流行地区的个体中，D180 的微丝蚴密度更高。这项研究表明，在首次接受伊维菌素治疗后测量的 O.volvulus 微丝蚴密度，因此可能是皮肤被微丝蚴重新填充的速度（mf），根据几个宿主因素而变化。如果这些因素也影响重复治疗后的伊维菌素疗效，那么应该考虑这些因素，以确定从非洲不同地区报告的治疗反应不理想是否实际上是由于寄生虫相关因素，特别是出现耐药种群。
