Background

Onchocerciasis in Yemen is one of the most neglected diseases, where baseline estimates of onchocerciasis and monitoring of the impact of ivermectin regularly administered to the affected individuals on its transmission are lacking. Therefore, this study aimed to determine the anti-Ov16 IgG4 seroprevalence among local communities of Hodeidah and Al-Mahwit governorates of Tihama Region. The factors possibly associated with previous exposure to infection were also studied.

Methodology/Principal findings

This cross-sectional study was conducted in two ivermectin-targeted districts endemic for onchocerciasis in Hodeidah and Al-Mahwit and two untargeted districts with unknown previous endemicity in Hodeidah between February and July 2017. For 508 residents sampled by a multi-stage random approach, data were collected and blood specimens were screened for anti-Ov16 IgG4 using the SD BIOLINE Onchocerciasis IgG4 rapid tests. The study revealed an overall anti-Ov16 IgG4 rate of 18.5% (94/508) in all surveyed districts, with 10.2% (12/118) of children aged ≤10 years being seropositive. Moreover, rates of 8.0% (4/50) and 6.1% (4/66) were found in districts not officially listed as endemic for the disease. Multivariable analysis confirmed the age of more than ten years and residing within a large family as the independent predictors of exposure to infection.

Conclusions/Significance

Onchocerciasis transmission is still ongoing as supported by the higher anti-Ov16 IgG4 seroprevalence rate among children aged ≤10 years compared to that (<0.1%) previously set by the World Health Organization as a serologic criterion for transmission interruption. Further large-scale studies combining serologic and entomologic criteria are recommended for the mapping of O. volvulus in human and blackfly populations in endemic foci and their neighboring areas of uncertain endemicity. In addition, ivermectin distribution, coverage and impact on disease transmission need to be continually assessed.

中文翻译：

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位于也门西部的蒂哈马州的Onchocerca volvulus感染：在以伊维菌素为靶标的地方性疫源地中继续传播，并在状态不明的地区发现了地方性流行病

背景

也门的盘尾丝虫病是最被忽视的疾病之一，目前尚缺乏对盘尾丝虫病的基线估计和对依维菌素定期给予受影响个体的伊维菌素影响的监测。因此，本研究旨在确定Tihama地区Hodeidah和Al-Mahwit省的当地社区之间的抗Ov 16 IgG4血清阳性率。还研究了可能与先前感染有关的因素。

方法/主要发现

这项横断面研究是在2017年2月至2017年7月期间，在荷迪达和Al-Mahwit的两个以伊维菌素为靶点的地方性盘尾丝虫病以及两个以前不知道流行性的无靶点的地方进行的。该研究针对508名居民，采用多阶段随机方法进行抽样，收集数据并使用SD BIOLINE盘尾丝虫病IgG4快速测试筛选血液样本中的抗Ov 16 IgG4。研究显示整体抗卵在所有调查地区中，16 IgG4率为18.5％（94/508），其中≤10岁儿童的血清抗体阳性率为10.2％（12/118）。此外，在没有被正式列为该病地方病的地区，发现该病的发生率分别为8.0％（4/50）和6.1％（4/66）。多变量分析证实年龄在十岁以上，并且是一个大家庭，是感染暴露的独立预测因子。

结论/意义

≤10岁儿童的抗Ov 16 IgG4血清阳性率较高，而世界卫生组织先前将其确定为传播中断的血清学标准（<0.1％），这证明了盘尾丝虫病的传播仍在继续。建议进一步结合血清学和昆虫学标准进行大规模研究，以绘制O的图。地方性疫源地及附近地区的地方性流行病中人类和粉虱种群的肠扭转。此外，需要不断评估伊维菌素的分布，覆盖范围以及对疾病传播的影响。