Evidence of transovarial transmission of Chikungunya and Dengue viruses in field-caught mosquitoes in Kenya
Evidence of transovarial transmission of Chikungunya and Dengue viruses in field-caught mosquitoes in Kenya
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DOI：
10.1371/journal.pntd.0008362
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发表时间：
2020-06-01
影响因子：
3.8
通讯作者：
LaBeaud, A. Desiree
中科院分区：
文献类型：
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作者：
Heath, Claire J.;Grossi-Soyster, Elysse N.;LaBeaud, A. Desiree
虫媒病毒是最重要的新兴病原体之一，因为它们对公共卫生的影响越来越大。在肯尼亚，持续的人口增长和相关的城市化有利于病媒在城市和农村环境中的传播，但在评估疫情风险时，往往忽视了病媒群体中病毒扩增的机制。因此，蚊子种群中虫媒病毒传播的特征对于更好地为风险评估和媒介控制实践提供信息至关重要。2014年1月至2016年5月，在肯尼亚4个不同地点的不同季节，在其生命周期的不同阶段捕获伊蚊，并采用RT-PCR检测基孔肯雅（CHIKV）、登革热（DENV）和寨卡（ZIKV）病毒。蚊池中检出CHIKV 45个（5.9%），DENV 3个（0.4%）。未检出寨卡病毒。在流行率方面观察到显著的区域差异，沿海地区发生CHIKV的频率更高。DENV只在海岸被发现。在两种性别的未成熟蚊子中均检测到这两种病毒，提供了这些虫媒病毒在当地蚊子中经卵巢传播的证据。这一现象可能推动潜在的病毒维持，这可能在很大程度上导致肯尼亚人类之间的周期性重新出现。经卵巢传播，或垂直传播，是一种病原体从父母到后代的传播。据观察，一些蚊媒病毒可在雌蚊卵泡发育或产卵期间由雌蚊传播给其后代。在受病毒感染的雄蚊（通常不吸血）和在任何性别的未成熟蚊子中都存在病毒时，经卵巢传播的发生是明显的。经卵巢传播增加了特定地区受感染蚊子的数量，从而扩大了病毒向人类传播的可能性，从而有助于蚊子传播的病毒在环境中扩增。经卵巢传播和在旱季保存活卵的结合可能引发病毒在雨季后突然扩增，从而导致暴发。本研究提供了基孔肯雅病毒和登革热病毒在非洲埃及伊蚊中跨社会传播的一些初步证据，这对当地病毒的持续存在和流行模式具有重要意义。
Arboviruses are among the most important emerging pathogens due to their increasing public health impact. In Kenya, continued population growth and associated urbanization are conducive to vector spread in both urban and rural environments, yet mechanisms of viral amplification in vector populations is often overlooked when assessing risks for outbreaks. Thus, the characterization of local arbovirus circulation in mosquito populations is imperative to better inform risk assessments and vector control practices. Aedes species mosquitoes were captured at varying stages of their life cycle during different seasons between January 2014 and May 2016 at four distinct sites in Kenya, and tested for chikungunya (CHIKV), dengue (DENV) and Zika (ZIKV) viruses by RT-PCR. CHIKV was detected in 45 (5.9%) and DENV in 3 (0.4%) mosquito pools. No ZIKV was detected. Significant regional variation in prevalence was observed, with greater frequency of CHIKV on the coast. DENV was detected exclusively on the coast. Both viruses were detected in immature mosquitoes of both sexes, providing evidence of transovarial transmission of these arboviruses in local mosquitoes. This phenomenon may be driving underlying viral maintenance that may largely contribute to periodic re-emergence among humans in Kenya.Author summary Transovarial transmission, or vertical transmission, is the spread of a pathogen from parent to offspring. It has been observed that some mosquito-borne viruses can be transmitted from female mosquitoes to their offspring during follicle development or during oviposition. The occurrence of transovarial transmission is evident in the presence of virally infected male mosquitoes, which typically do not take bloodmeals, and the presence of virus in immature mosquitoes of any sex. Transovarial transmission aids in the amplification of mosquito-borne viruses in the environment by increasing the number of infected mosquitoes in a given region, thus expanding the possibility of viral transmission to humans. The combination of transovarial transmission and the preservation of viable eggs during dry seasons may trigger sudden amplification of the virus after rainy periods, resulting in an outbreak. This study provides some of the first evidence of transovarial transmission of chikungunya and dengue viruses in Aedes aegypti mosquitoes in Africa during interepidemic periods, which has important implications for local virus persistence and epidemic patterns.