Centre for Research in Infectious Diseases, Yaoundé, Cameroon.
Department of Animal Biology, Faculty of Sciences, University of Yaoundé I, Yaoundé, Cameroon.
PLoS Negl Trop Dis. 2019 Mar 18;13(3):e0007137. doi: 10.1371/journal.pntd.0007137. eCollection 2019 Mar.
Arboviral diseases including dengue are increasingly spreading in the tropical/subtropical world including Africa. Updated knowledge on the distribution and abundance of the major vectors Aedes aegypti and Aedes albopictus constitutes crucial surveillance action to prepare African countries such as Cameroon for potential arbovirus outbreaks. Here, we present a nationwide survey in Cameroon to assess the current geographical distribution and prevalence of both vectors including a genetic diversity profiling of Ae. albopictus (invasive species) using mitochondrial DNA.
Immature stages of Aedes were collected between March and August 2017 in 29 localities across Cameroon following north-south and east-west transects. Larvae and pupae were collected from several containers in each location, reared to adult and morphologically identified. Genetic diversity of Ae. albopictus from 16 locations were analysed using Cytochrome Oxidase I gene (COI).
In total, 30,381 immature stages of Aedes with an average of 646.40±414.21 per location were identified across the country comprising 69.3% of Ae. albopictus and 30.7% of Ae. aegypti. Analysis revealed that Ae. aegypti is still distributed nation widely whereas Ae. albopictus is limited to the southern part, around 6°4'N. However, Ae. albopictus is the most prevalent species in all southern locations where both species are sympatric except in Douala where Ae. aegypti is predominant. This suggests that factors such as climate, vegetation, and building density impact the distribution of both species in Cameroon. Mitochondrial DNA analysis revealed a low genetic diversity in Ae. albopictus populations with a major common haplotype resulting in low haplotype diversity ranging from 0.13 to 0.65 and 0.35 for the total sample. Similarly, low nucleotide diversity was also reported varying from 0.0000 to 0.0017 with an overall index of 0.0008. This low genetic polymorphism is consistent with the recent introduction of Ae. albopictus in Cameroon.
This updated distribution of arbovirus vectors across Cameroon will help in planning vector control programme against possible outbreak of arbovirus related diseases in the country.
包括登革热在内的虫媒病毒疾病在包括非洲在内的热带/亚热带地区日益蔓延。及时了解主要传播媒介埃及伊蚊和白纹伊蚊的分布和丰度，是为喀麦隆等非洲国家做好潜在虫媒病毒病暴发准备的关键监测行动。在这里，我们在喀麦隆进行了一次全国性调查，以评估这两种媒介的当前地理分布和流行情况，包括使用线粒体 DNA 对白纹伊蚊（入侵物种）进行遗传多样性分析。
2017 年 3 月至 8 月，沿南北和东西方向在喀麦隆 29 个地点采集了成蚊的幼虫和蛹。在每个地点的多个容器中采集幼虫和蛹，将其饲养至成虫并进行形态鉴定。使用细胞色素氧化酶 I 基因（COI）对来自 16 个地点的白纹伊蚊的遗传多样性进行了分析。
共鉴定出全国范围内的 30381 只成蚊幼虫，平均每个地点有 646.40±414.21 只，其中 69.3%为白纹伊蚊，30.7%为埃及伊蚊。分析表明，埃及伊蚊仍广泛分布于全国，而白纹伊蚊则局限于南部，约 6°4'N。然而，在这两种蚊种共存的所有南部地区，白纹伊蚊是最常见的物种，除了杜阿拉，那里埃及伊蚊占优势。这表明气候、植被和建筑密度等因素影响着这两种蚊种在喀麦隆的分布。线粒体 DNA 分析显示，白纹伊蚊种群的遗传多样性较低，主要的共同单倍型导致低单倍型多样性，从 0.13 到 0.65 和 0.35 不等，总样本的多样性为 0.35。同样，报道的核苷酸多样性也很低，从 0.0000 到 0.0017 不等，总指数为 0.0008。这种低遗传多态性与白纹伊蚊在喀麦隆的近期引入相一致。
本研究更新了喀麦隆虫媒病毒病传播媒介的分布情况，有助于规划该国针对可能爆发的虫媒病毒病相关疾病的病媒控制计划。
