Institute for Parasitology and Tropical Veterinary Medicine, Freie Universitaet Berlin, Berlin, Germany.
International Livestock Research Institute, Nairobi, Kenya.
Vector Borne Zoonotic Dis. 2020 May;20(5):365-373. doi: 10.1089/vbz.2019.2503. Epub 2020 Jan 28.
Environmental modifications disturb the equilibrium of mosquito populations, altering the risk of mosquito-borne diseases. Mosquito distribution, diversity, and bloodmeal sources were examined to compare Rift Valley fever (RVF) risk among irrigated, riverine, and pastoral ecosystems in Bura, Tana River County, Kenya, between September 2014 and June 2015. Thirty-eight households and 21 irrigation fields were selected for the study. Mosquitoes were trapped with carbon dioxide-impregnated CDC traps, one trap per household and three traps per irrigated field, and morphologically identified using taxonomic keys. Host DNA was extracted from engorged females and cytochrome b genes amplified by PCR to identify sources of bloodmeals. A total of 21,015 mosquitoes were collected; 5742 within households in the 3 ecosystems and 15,273 within irrigated fields. Mosquitoes collected within irrigated fields belonged to 8 genera and 37 species, while those from households within the irrigation scheme belonged to 6 genera and 29 species. Collections from riverine and pastoral households belonged to five and four genera, respectively. The most abundant genera in the irrigated fields were (21%) and (22%), while (43%) was the most abundant within households. Most mosquitoes in riverine and pastoral households belonged to (76%) and (65%) genera, respectively. Seasonal variation driven by rainfall was evidenced by spikes in mosquito numbers within irrigated and riverine ecosystems. Host species identification revealed that goats and humans were the main sources of bloodmeal. There was an overall increase in mosquito abundance and diversity as a result of the presence of the irrigated ecosystem in this county, and an increased availability of highly RVF-susceptible hosts as a result of the establishment and concentration of residential areas, promoting potential vector-host contacts. These results highlight the impact of anthropogenic changes on mosquito ecology, potentially heightening the risk of transmission and maintenance of RVF in this region.
环境改变扰乱了蚊虫种群的平衡，改变了蚊媒疾病的风险。本研究于 2014 年 9 月至 2015 年 6 月在肯尼亚塔纳河郡的布拉地区比较了灌溉、河流和牧区生态系统中裂谷热（RVF）的风险，调查了蚊虫的分布、多样性和吸血来源。研究选择了 38 户家庭和 21 个灌溉区。用含有二氧化碳的 CDC 诱蚊器在每个家庭和每个灌溉区捕获 3 个诱蚊器捕获蚊虫，并用分类学钥匙对其进行形态鉴定。从吸血后的雌性蚊虫中提取宿主 DNA，通过 PCR 扩增细胞色素 b 基因来鉴定血源。共采集 21015 只蚊虫，其中 5742 只为 3 种生态系统中的家庭蚊虫，15273 只为灌溉区蚊虫。从灌溉区采集的蚊虫属于 8 个属和 37 个种，而从灌溉区家庭采集的蚊虫属于 6 个属和 29 个种。从河流和牧区家庭采集的蚊虫分别属于 5 个和 4 个属。在灌溉区最丰富的属是 （21%）和 （22%），而在家庭中最丰富的是 （43%）。河流和牧区家庭中最丰富的属分别是 （76%）和 （65%）。降雨引起的季节性变化导致灌溉和河流生态系统中蚊虫数量的增加。宿主种类鉴定表明，山羊和人类是主要的血源。由于该县灌溉生态系统的存在，蚊虫的数量和多样性总体上有所增加，由于居住区域的建立和集中，高 RVF 易感性宿主的可用性增加，从而促进了潜在的媒介-宿主接触。这些结果突出了人为变化对蚊虫生态学的影响，可能使该地区 RVF 的传播和维持风险增加。
