Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK.
Laboratory of Pathogen-Host Interactions (LPHI), UMR5235, CNRS, Montpellier University, 34095, Montpellier, France.
Parasit Vectors. 2020 Sep 21;13(1):481. doi: 10.1186/s13071-020-04356-z.
Aedes spp. are responsible for the transmission of many arboviruses, which contribute to rising human morbidity and mortality worldwide. The Aedes aegypti mosquito is a main vector for chikungunya, dengue and yellow fever infections, whose incidence have been increasing and distribution expanding. This vector has also driven the emergence of the Zika virus (ZIKV), first reported in Africa which spread rapidly to Asia and more recently across the Americas. During the outbreak in the Americas, Cape Verde became the first African country declaring a Zika epidemic, with confirmed cases of microcephaly. Here we investigate the prevalence of ZIKV and dengue (DENV) infected Ae. aegypti mosquitoes in the weeks following the outbreak in Cape Verde, and the presence of insecticide resistance in the circulating vector population. Genetic diversity in the mosquito population was also analysed.
From August to October 2016, 816 Ae. aegypti mosquitoes were collected in several locations across Praia, Cape Verde, the major hot spot of reported ZIKV cases in the country. All mosquitoes were screened by reverse transcription PCR for ZIKV and DENV, and a subset (n = 220) were screened for knockdown insecticide resistance associated mutations in the voltage gated sodium channel (VGSC) gene by capillary sequencing. The mitochondrial NADH dehydrogenase subunit 4 (nad4) gene was sequenced in 100 mosquitoes. These data were compared to 977 global sequences in a haplotype network and a phylogenetic tree analysis.
Two Ae. aegypti mosquitoes were ZIKV positive (0.25%). There were no SNP mutations found in the VGSC gene associated with insecticide resistance. Analysis of the nad4 gene revealed 11 haplotypes in the Cape Verdean samples, with 5 being singletons. Seven haplotypes were exclusive to Cape Verde. Several of the remaining haplotypes were frequent in the global dataset, being present in several countries (including Cape Verde) across five different continents. The most common haplotype in Cape Verde (50.6 %) was also found in Africa and South America.
There was low-level Zika virus circulation in mosquitoes from Praia shortly after the outbreak. The Ae. aegypti population did not appear to have the kdr mutations associated with pyrethroid resistance. Furthermore, haplotype and phylogenetic analyses revealed that Cape Verde Ae. aegypti mosquitoes are most closely related to those from other countries in Africa and South America.
埃及伊蚊是许多虫媒病毒的传播媒介，导致全球人类发病率和死亡率上升。埃及伊蚊是基孔肯雅热、登革热和黄热病感染的主要媒介，其发病率不断上升，分布范围不断扩大。这种媒介还导致寨卡病毒（ZIKV）的出现，该病毒最初在非洲报告，迅速传播到亚洲，最近又传播到美洲。在美洲疫情期间，佛得角成为第一个宣布寨卡疫情的非洲国家，已确认有小头畸形病例。在这里，我们调查了佛得角疫情爆发后几周内埃及伊蚊中寨卡病毒和登革热（DENV）感染的流行情况，以及循环媒介种群中杀虫剂耐药性的存在。还分析了蚊子种群的遗传多样性。
2016 年 8 月至 10 月，在佛得角普拉亚的几个地点收集了 816 只埃及伊蚊。所有蚊子均通过逆转录聚合酶链反应（RT-PCR）筛查寨卡病毒和登革热，其中亚组（n=220）通过毛细管测序筛查电压门控钠通道（VGSC）基因中的击倒型杀虫剂抗性相关突变。在 100 只蚊子中测序了线粒体 NADH 脱氢酶亚单位 4（nad4）基因。这些数据与单倍型网络和系统发育树分析中的 977 个全球序列进行了比较。
有 2 只埃及伊蚊寨卡病毒阳性（0.25%）。在与杀虫剂抗性相关的 VGSC 基因中未发现 SNP 突变。nad4 基因分析显示，佛得角样本中有 11 种单倍型，其中 5 种为单倍型。7 种单倍型仅存在于佛得角。其余的一些单倍型在全球数据集也很常见，存在于五个不同大陆的几个国家（包括佛得角）。佛得角最常见的单倍型（50.6%）也存在于非洲和南美洲。
在疫情爆发后不久，从普拉亚采集的蚊子中发现了低水平的寨卡病毒循环。埃及伊蚊种群似乎没有与拟除虫菊酯抗性相关的 kdr 突变。此外，单倍型和系统发育分析表明，佛得角埃及伊蚊与非洲和南美洲其他国家的蚊子最为密切相关。
