IRD UMI 233, INSERM U1175, Montpellier University, France.
Centre for Research on Filariasis and Other Tropical Diseases, Yaoundé, Cameroon.
Clin Infect Dis. 2018 Feb 10;66(5):751-757. doi: 10.1093/cid/cix877.
For a given prevalence of Loa loa microfilaremia, the proportion of people with high densities varies significantly between communities. We hypothesized that this variation is related to the existence of familial clusters of hypermicrofilaremic individuals that would be the consequence of a genetic predisposition to present high L. loa microfilarial densities.
A familial study was performed in 10 villages in the Okola Health District of Cameroon. Intrafamilial correlation coefficients and heritability estimates were assessed for both the presence of L. loa microfilaremia and individual microfilarial densities by controlling for age, sex, Mansonella perstans coinfection, and household effects.
Pedigrees were constructed for 1126 individuals. A significant familial susceptibility to be microfilaremic for L. loa was found for first-degree relatives (ρ = 0.08, P < .05; heritability = 0.23). Regarding individual microfilarial densities, a significant familial aggregation was demonstrated (ρ = 0.36 for first-degree and 0.27 for second-degree relatives). For first-degree relatives, the highest coefficient was found between mothers and daughters (ρ = 0.57). The overall heritability estimate for L. loa microfilarial density was 0.24 (P = .003).
A significant genetic component governs L. loa microfilarial density. This supports the hypothesis that a genetic predisposition to be hypermicrofilaremic exists, leading to the presence of familial clusters of individuals at risk for postivermectin severe adverse events. This finding should be taken into account while developing sampling strategies (including a household-level sampling) to identify villages where community-directed treatment with ivermectin cannot be applied.
在已知的旋毛形线虫微丝蚴流行率下，人群中高密度的比例在社区之间存在显著差异。我们假设这种差异与存在高微丝蚴血症个体的家族聚集有关，这可能是由于存在对呈现高旋毛形线虫微丝蚴密度的遗传易感性。
在喀麦隆奥科拉卫生区的 10 个村庄进行了一项家族研究。通过控制年龄、性别、曼森线虫共感染和家庭效应，评估了旋毛形线虫微丝蚴血症的存在和个体微丝蚴密度的家族内相关系数和遗传度估计值。
构建了 1126 个人的家系。发现一级亲属对旋毛形线虫微丝蚴血症存在显著的家族易感性（ρ=0.08，P<.05；遗传度=0.23）。关于个体微丝蚴密度，显示出显著的家族聚集性（一级亲属为ρ=0.36，二级亲属为ρ=0.27）。对于一级亲属，最高的相关系数出现在母亲和女儿之间（ρ=0.57）。旋毛形线虫微丝蚴密度的总体遗传度估计值为 0.24（P=0.003）。
遗传因素对旋毛形线虫微丝蚴密度有显著影响。这支持了一种假设，即存在对高微丝蚴血症的遗传易感性，导致存在处于伊维菌素后严重不良反应风险的个体的家族聚集。在制定抽样策略（包括家庭层面的抽样）以确定不能应用社区定向伊维菌素治疗的村庄时，应考虑这一发现。
