Laboratorio de Biología de Vectores y Parásitos, Instituto de Zoología y Ecología Tropical, Facultad de Ciencias, Universidad Central de Venezuela, Apartado Postal 47072, Caracas 1041-A, Venezuela.
Parasit Vectors. 2013 Oct 7;6(1):289. doi: 10.1186/1756-3305-6-289.
Onchocerciasis is caused by Onchocerca volvulus and transmitted by Simulium species (black flies). In the Americas, the infection has been previously described in 13 discrete regional foci distributed among six countries (Brazil, Colombia, Ecuador, Guatemala, Mexico and Venezuela) where more than 370,000 people are currently considered at risk. Since 2001, disease control in Venezuela has relied on the mass drug administration to the at-risk communities. This report provides empirical evidence of interruption of Onchocerca volvulus transmission by Simulium metallicum in 510 endemic communities from two Northern foci of Venezuela, after 10-12 years of 6-monthly Mectizan (ivermectin) treatment to all the eligible residents.
In-depth entomologic and epidemiologic surveys were serially conducted from 2001-2012 in selected (sentinel and extra-sentinel) communities from the North-central (NC) and North-east (NE) onchocerciasis foci of Venezuela in order to monitor the impact of ivermectin treatment.
From 2007-2009, entomological indicators in both foci confirmed that 0 out of 112,637 S. metallicum females examined by PCR contained L3 infection in insect heads. The upper bound of the 95% confidence intervals of the infective rate of the vector reached values below 1% by 2009 (NC) and 2012 (NE). Additionally, after 14 (NC) and 22 (NE) rounds of treatment, the seasonal transmission potential (±UL CIs) of S. metallicum was under the critical threshold of 20 L3 per person per season. Serological analysis in school children < 15 years-old demonstrated that 0 out of 6,590 individuals were harboring antibodies to Ov-16. Finally, epidemiological surveys made during 2010 (NC) and 2012 (NE) showed no evidence of microfilariae in the skin and eyes of the population.
These results meet the WHO criteria for absence of parasite transmission and disease morbidity in these endemic areas which represent 91% of the population previously at-risk in the country. Consequently, the two Northern foci are currently under post-treatment onchocerciasis surveillance status in Venezuela.
盘尾丝虫病由盘尾丝虫引起，由类蚋属（黑蝇）传播。在美洲，该感染曾在分布于六个国家（巴西、哥伦比亚、厄瓜多尔、危地马拉、墨西哥和委内瑞拉）的 13 个离散区域性流行地区中被描述，目前有超过 37 万人被认为处于危险之中。自 2001 年以来，委内瑞拉的疾病控制依赖于对高危社区的大规模药物管理。本报告提供了实证证据，证明在对委内瑞拉两个北部流行地区的 510 个流行社区进行了 10-12 年的每六个月一次的美代菌素（伊维菌素）治疗后，类蚋属中的旋盘尾丝虫传播已被中断。
为了监测伊维菌素治疗的影响，从 2001 年至 2012 年，在委内瑞拉中北部（NC）和东北部（NE）的选定（哨点和非哨点）社区中，连续进行了深入的昆虫学和流行病学调查。
从 2007 年至 2009 年，两个流行地区的昆虫学指标均证实，通过 PCR 检查的 112637 只类蚋属雌性中，没有一只含有虫体头部的 L3 感染。到 2009 年（NC）和 2012 年（NE），媒介感染率的 95%置信区间上限达到了 1%以下。此外，在进行了 14 轮（NC）和 22 轮（NE）治疗后，类蚋属的季节性传播潜力（±UL CIs）低于每人每季 20 条 L3 的临界阈值。对年龄在 15 岁以下的学童进行的血清学分析显示，6590 名个体中没有一人携带 Ov-16 抗体。最后，2010 年（NC）和 2012 年（NE）进行的流行病学调查显示，人群的皮肤和眼睛中均未发现微丝蚴。
这些结果符合世界卫生组织关于这些流行地区寄生虫传播和疾病发病率不存在的标准，这些地区占该国以前高危人群的 91%。因此，委内瑞拉的这两个北部流行地区目前处于治疗后盘尾丝虫病监测状态。
