Ethiopian Public Health Institute, Addis Ababa, Ethiopia.
Department of Biology, Arba Minch University, Arba Minch, Ethiopia.
Malar J. 2019 Nov 8;18(1):357. doi: 10.1186/s12936-019-2988-3.
Insecticide resistance is a growing threat to malaria vector control. Ivermectin, either administered to humans or animals, may represent an alternate strategy to reduce resistant mosquito populations. The aim of this study was to assess the residual or delayed effect of administering a single oral dose of ivermectin to humans on the survival, fecundity and fertility of Anopheles arabiensis in Ethiopia.
Six male volunteers aged 25-40 years (weight range 64-72 kg) were recruited; four of them received a recommended single oral dose of 12 mg ivermectin and the other two individuals were untreated controls. A fully susceptible insectary colony of An. arabiensis was fed on treated and control participants at 1, 4, 7, 10 and 13 days post ivermectin-administration. Daily mosquito mortality was recorded for 5 days. An. arabiensis fecundity and fertility were measured from day 7 post treatment, by dissection to examine the number of eggs per mosquito, and by observing larval hatching rates, respectively.
Ivermectin treatment induced significantly higher An. arabiensis mortality on days 1 and 4, compared to untreated controls (p = 0.02 and p < 0.001, respectively). However, this effect had declined by day 7, with no significant difference in mortality between treated and control groups (p = 0.06). The mean survival time of mosquitoes fed on day 1 was 2.1 days, while those fed on day 4 survived 4.0 days. Mosquitoes fed on the treatment group at day 7 and 10 produced significantly lower numbers of eggs compared to the untreated controls (p < 0.001 and p = 0.04, respectively). An. arabiensis fed on day 7 on treated men also had lower larval hatching rates than mosquitoes fed on days 10 and 13 (p = 0.003 and p = 0.001, respectively).
A single oral dose of ivermectin given to humans can induce mortality and reduce survivorship of An. arabiensis for 7 days after treatment. Ivermectin also had a delayed effect on fecundity of An. arabiensis that took bloodmeals from treated individuals on day 7 and 10. Additional studies are warranted using wild, insecticide-resistant mosquito populations, to confirm findings and a phase III evaluation among community members in Ethiopia is needed to determine the impact of ivermectin on malaria transmission.
杀虫剂耐药性是疟疾媒介控制的一个日益严重的威胁。伊维菌素，无论是给予人类还是动物，都可能代表一种减少抗蚊种群的替代策略。本研究的目的是评估给人类服用单口服剂量伊维菌素对埃塞俄比亚阿拉伯按蚊的生存、繁殖力和生殖力的残留或延迟影响。
招募了 6 名年龄在 25-40 岁（体重范围为 64-72 公斤）的男性志愿者；其中 4 名志愿者接受了推荐的单口服剂量 12 毫克伊维菌素，另外 2 名志愿者为未治疗对照。在给予伊维菌素后 1、4、7、10 和 13 天，用处理过和对照志愿者喂养完全敏感的按蚊虫饲养室。每天记录 5 天的蚊子死亡率。从治疗后第 7 天开始，通过解剖检查每只蚊子的产卵数和观察幼虫孵化率来测量阿拉伯按蚊的繁殖力和生殖力。
与未治疗对照组相比，伊维菌素处理组在第 1 天和第 4 天导致阿拉伯按蚊死亡率显著升高（p=0.02 和 p<0.001）。然而，这种效应在第 7 天已经下降，处理组和对照组之间的死亡率没有显著差异（p=0.06）。第 1 天喂养的蚊子的平均存活时间为 2.1 天，而第 4 天喂养的蚊子存活 4.0 天。第 7 天和第 10 天喂养处理组的蚊子产蛋量明显低于未治疗对照组（p<0.001 和 p=0.04）。第 7 天喂养处理组的蚊子与第 10 天和第 13 天喂养的蚊子相比，幼虫孵化率也较低（p=0.003 和 p=0.001）。
给人类服用单口服剂量的伊维菌素可在治疗后 7 天内诱导阿拉伯按蚊的死亡率并降低其存活率。伊维菌素对第 7 天和第 10 天从处理个体吸血的阿拉伯按蚊的繁殖力也有延迟效应。需要使用野生、抗杀虫剂的蚊子种群进行进一步研究，以确认研究结果，还需要在埃塞俄比亚的社区成员中进行 III 期评估，以确定伊维菌素对疟疾传播的影响。
