Molecular detection of Leishmania infantum DNA and host blood meal identification in Phlebotomus in a hypoendemic focus of human leishmaniasis in northern Algeria
Molecular detection of Leishmania infantum DNA and host blood meal identification in Phlebotomus in a hypoendemic focus of human leishmaniasis in northern Algeria
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DOI：
10.1371/journal.pntd.0006513
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发表时间：
2018-06-01
影响因子：
3.8
通讯作者：
Parola, Philippe
中科院分区：
文献类型：
--
作者：
Bennai, Kahina;Tahir, Djamel;Parola, Philippe
研究背景利什曼原虫是由雌性白蛉传播的寄生虫，白蛉通过在森林哺乳动物和家养哺乳动物之间循环来维持地方性流行周期。人类是这个循环的一部分，由于媒介寻找血液来源而成为偶然的宿主。在阿尔及利亚，人类利什曼病（HL）是地方性疾病，由于其每年的高发病率和遍布全国，因此是一个严重的公共卫生问题。本研究的目的是确定白蛉物种区系（利什曼原虫病媒），在位于蒂帕萨省的HL低地方病疫源地中，使用分子工具确定其感染率并确定其进食偏好，阿尔及利亚北方。方法/主要发现2015年7月至10月期间，在四个受HL影响的国家中使用CDC灯诱捕器进行了昆虫学调查。阿尔及利亚北方蒂帕萨省的城市位置。白蛉的雄性和雌性受精囊的生殖器的形态标准进行了鉴定。使用靶向两种不同基因（kDNA-PCR和18 S rRNA）的定量实时聚合酶链反应（qPCR），在合并的雌性白蛉（N = 81个样本池，每个样本池8 +/- 10个样本）中检测利什曼原虫DNA。为了确定它们的血餐来源，通过针对脊椎动物细胞色素c氧化酶I（COI）基因的PCR测序分析了吸血雌性白蛉。共捕获白蛉4，045只，其中3，727只进行了形态学鉴定。共记录到7种植物：P.（L.）perniciosus（50.28%）、P.（L.）细丝叶蝉（26.13%）、黑腹叶蝉（P.（L.）长突叶蝉（21.92%）、长尾叶蝉（S.）minuta（0.85%），P.（P.）papatasi（0.42%）、拟青霉P.（L.）langeroni（0.32%）和P.（L.）阿里亚斯（0.05%）。然后，随机选择740名女性标本，分成81个样本池，然后进行筛选，以调查利什曼原虫属的存在。L.在对应于三个白蛉样本（各一个）的三个池中检测到婴儿DNA。感染率为0.33%（2/600）。perniciosus和P.（L.）perfiliewi。对88只白蛉的血食来源分析表明，白蛉属Larroussius亚属，主要以小反刍动物为食（71.5%）。人血是第二食物来源（17%），8个标本（9%）被发现以马为食，没有发现家庭水库（狗）的血液。infantum的检测，以及L.（L.）perniciosus，P.（L.）perfiliewi），并对L.婴儿血中的血凝素水平，证明血凝素是血凝素流行病学传播周期的主要环节。婴儿中的感染病例表明，蒂帕萨省存在暴发该疾病的危险因素。
BackgroundLeishmania parasites are transmitted by female phlebotomine sand flies that maintain the enzootic cycle by circulating between sylvatic and domestic mammals. Humans are part of this cycle as accidental hosts due to the vector's search for a source of blood. In Algeria, Human Leishmaniases (HL) are endemic and represent a serious public health problem because of their high annual incidence and their spread across the country. The aim of this study is to identify sand fly species fauna (vectors of Leishmania), determine their infection rate and identify their feeding preferences using molecular tools in a hypoendemic focus of HL located in the province of Tipaza, northern Algeria.Methodology/Principal findingsAn entomological survey using CDC light traps was conducted between July and October of 2015 in four HL affected peri-urban locations in the province of Tipaza, northern Algeria. Sand flies were identified using the morphological criteria of the genitalia for the males and spermathecae for the females. Leishmania DNA was detected in pooled female sand flies (N = 81 pools with 8 +/- 10 specimens per pool) using quantitative real-time polymerase chain reaction (qPCR) targeting two different genes: kDNA-PCR and 18S rRNA. To identify their blood meal sources, blood-fed female sand flies were analyzed by PCR-sequencing targeting the vertebrate cytochrome c oxidase I (COI) gene. A total of 4,045 sand flies were caught, of which 3,727 specimens were morphologically identified. Seven species were recorded: P. (L.) perniciosus (50.28%), P. (L.) perfiliewi (26.13%), P. (L.) longicuspis (21.92%), Sergentomyia (S.) minuta (0.85%), P. (P.) papatasi (0.42%), P. (L.) langeroni (0.32%) and P. (L.) ariasi (0.05%). Afterwards, 740 female specimens were randomly selected and divided into 81 pools and were then screened to investigate the presence of Leishmania spp. L. infantum DNA was detected in three pools, corresponding to three sand fly specimens (one each). The infection rate was 0.33% (2/600) for P. (L.) perniciosus and 2.56% (1/39) for P. (L.) perfiliewi. Analysis of the blood feeding sources (N = 88 specimens) revealed that sand flies belonging to Larroussius subgenera, mainly (71.5%) feed on small ruminants. Human blood is the second feeding source (17%), eight specimens (9%) were found to feed on equines and no domestic reservoir (dog) blood was found.Conclusions/SignificanceThe presence of human leishmaniasis cases, the high abundance of Phlebotomus (Larroussius) species which are proven or suspected vectors of L. infantum, and the detection of L. infantum DNA from its natural vectors (P. (L.) perniciosus, P. (L.) perfiliewi), in addition to the blood-feeding of positive females for L. infantum on humans blood, prove that the major elements of the epidemiological transmission cycle of L. infantum are present and indicate risk factors for an outbreak of the disease in the province of Tipaza.