Abduselam Nuredin, Zeynudin Ahmed, Berens-Riha Nicole, Seyoum Dinberu, Pritsch Michael, Tibebu Habtewold, Eba Kasahun, Hoelscher Michael, Wieser Andreas, Yewhalaw Delenasaw
Department of Medical Laboratory Sciences and Pathology, College of Public Health and Medical Science, Jimma University, Jimma, Ethiopia.
Department of Bacteriology, Max von Pettenkofer-Institute (LMU), Munich, Germany.
Parasit Vectors. 2016 Oct 18;9(1):552. doi: 10.1186/s13071-016-1839-0.
Around half of the global population is living in areas at risk of malaria infection. Plasmodium vivax malaria has become increasingly prevalent and responsible for a high health and socio-economic burden in Ethiopia. The availability of gametocyte carriers and mosquito species susceptible to P. vivax infection are vital for malaria transmission. Determining the susceptibility of vector species to parasite infection in space and time is important in vector control programs. This study assesses the susceptibility of Anopheles arabiensis, An. pharoensis and An. coustani group to Plasmodium vivax infection in Ethiopia.
Larvae of An. arabiensis, An. pharoensis and An. coustani group were collected from an array of breeding sites and reared to adult under controlled conditions. Batches of adult female mosquitoes of the three species were allowed to feed in parallel on the same infected blood with gametocytes drawn from Plasmodium vivax infected patients by Direct Membrane Feeding Assays (DMFA). Fed mosquitoes were kept in an incubator under controlled laboratory conditions. Seven days after each feeding assay, mosquitoes were dissected for midgut oocyst microscopy and enumeration. Data were analysed using R statistical software package version 3.1.0.
Over all, 8,139 adult female mosquitoes were exposed to P. vivax infection. Of the exposed mosquitoes 16.64 % (95 % CI: 1,354-8,139) were properly fed and survived until dissection. The infection rate in An. arabiensis and An. pharoensis was 31.72 % (95 % CI: 28.35-35.08) and 28.80 % (95 % CI: 25.31-32.28), respectively. The intensity of infection for An. arabiensis and An. pharoensis was 2.5 (95 % CI: 1.9-3.2) and 1.4 (95 % CI: 1.1-1.8), respectively. Gametocyte density was positively correlated to infection rate and intensity of infection in An. arabiensis as well as An. pharoensis. No An. coustani group mosquitoes were found infected, though almost four hundred mosquitoes were successfully fed and dissected. All groups received blood from the same infected blood source containing gametocytes in parallel. There was no significant difference in susceptibility rates between An. arabiensis and An. pharoensis (P = 0.215).
Anopheles arabiensis and An. pharoensis showed similar susceptibility to P. vivax infection. However, An. coustani group was not permissive for the development of P. vivax parasites.
全球约一半人口生活在有疟疾感染风险的地区。间日疟原虫疟疾在埃塞俄比亚日益流行，造成了高昂的健康和社会经济负担。配子体携带者的存在以及对间日疟原虫感染敏感的蚊种对于疟疾传播至关重要。在病媒控制项目中，确定病媒物种在空间和时间上对寄生虫感染的易感性很重要。本研究评估了阿拉伯按蚊、法老按蚊和库斯塔尼按蚊种群对埃塞俄比亚间日疟原虫感染的易感性。
从一系列繁殖地收集阿拉伯按蚊、法老按蚊和库斯塔尼按蚊种群的幼虫，并在受控条件下饲养至成虫。通过直接膜饲法（DMFA），让这三种成年雌性蚊子批次并行吸食来自间日疟原虫感染患者的含有配子体的同一感染血液。喂食后的蚊子置于受控实验室条件的培养箱中。每次喂食试验7天后，解剖蚊子进行中肠卵囊显微镜检查和计数。使用R统计软件包版本3.1.0分析数据。
总体而言，8139只成年雌性蚊子暴露于间日疟原虫感染。在暴露的蚊子中，16.64%（95%置信区间：1354 - 8139）正常进食并存活至解剖。阿拉伯按蚊和法老按蚊的感染率分别为31.72%（95%置信区间：28.35 - 35.08）和28.80%（95%置信区间：25.31 - 32.28）。阿拉伯按蚊和法老按蚊的感染强度分别为2.5（95%置信区间：1.9 - 3.2）和1.4（95%置信区间：1.1 - 1.8）。配子体密度与阿拉伯按蚊和法老按蚊的感染率及感染强度呈正相关。尽管解剖了近四百只成功喂食的库斯塔尼按蚊种群蚊子，但未发现有感染的情况。所有组并行接受来自同一含有配子体的感染血液来源的血液。阿拉伯按蚊和法老按蚊的易感性率无显著差异（P = 0.215）。
阿拉伯按蚊和法老按蚊对间日疟原虫感染表现出相似的易感性。然而，库斯塔尼按蚊种群不允许间日疟原虫寄生虫发育。
