The Relative Contribution of Symptomatic and Asymptomatic Plasmodium vivax and Plasmodium falciparum Infections to the Infectious Reservoir in a Low-Endemic Setting in Ethiopia
The Relative Contribution of Symptomatic and Asymptomatic Plasmodium vivax and Plasmodium falciparum Infections to the Infectious Reservoir in a Low-Endemic Setting in Ethiopia
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DOI：
10.1093/cid/cix1123
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发表时间：
2018-06-15
影响因子：
11.8
通讯作者：
Bousema, Teun
中科院分区：
文献类型：
--
作者：
Tadesse, Fitsum G.;Slater, Hannah C.;Bousema, Teun
背景资料。间日疟原虫和恶性疟原虫在低流行环境中的大多数感染是无症状的。与临床疟疾病例相比，这些感染对感染性宿主的相对贡献目前尚不清楚。我们评估了被动招募的有症状疟疾患者(n=41)和社区招募的无症状个体的传染性，采用显微镜检测(n=41)和聚合酶链式反应(PCR)检测的感染(n=82)，使用埃塞俄比亚阿达玛阿拉伯按蚊的膜喂养试验。利用疟疾发病率和流行率数据估计这些人群对传染病流行的贡献。总体而言，34.9%(29/83)间日疟原虫感染者和15.1%(8/53)恶性疟原虫感染者=1只蚊子。间日疟原虫的蚊虫感染率与无性寄生虫密度密切相关(Rho=0.63；P&t；.001)，而恶性疟原虫的蚊虫感染率与无性寄生虫密度无关(Rho=0.06；P=.770)。间日疟原虫的症状感染对蚊子的传染性(感染46.5%的蚊子，307/660)比无症状镜检(感染12.0%的蚊子，80/667；P=.005)和聚合酶链式反应检测的感染(感染0.8%的蚊子，6/744；P<；.001)更具传染性。调整人群流行率后，有症状的、无症状的镜检和聚合酶链式反应检测的感染分别占间日疟原虫感染库的8.0%、76.2%和15.8%。恶性疟原虫以蚊虫感染较少，也以无症状感染为主。在这一旨在消除疟疾的低流行环境中，无症状感染非常普遍，是大多数后续蚊子感染的原因。及早发现和治疗无症状感染可能会加速消除努力。
Background. The majority of Plasmodium vivax and Plasmodium falciparum infections in low-endemic settings are asymptomatic. The relative contribution to the infectious reservoir of these infections compared to clinical malaria cases is currently unknown.Methods. We assessed infectivity of passively recruited symptomatic malaria patients (n = 41) and community-recruited asymptomatic individuals with microscopy-detected (n = 41) and polymerase chain reaction (PCR)-detected infections (n = 82) using membrane feeding assays with Anopheles arabiensis mosquitoes in Adama, Ethiopia. Malaria incidence and prevalence data were used to estimate the contributions of these populations to the infectious reservoir.Results. Overall, 34.9% (29/83) of P. vivax-and 15.1% (8/53) P. falciparum-infected individuals infected = 1 mosquitoes. Mosquito infection rates were strongly correlated with asexual parasite density for P. vivax (rho = 0.63; P < .001) but not for P. falciparum (rho = 0.06; P = .770). Plasmodium vivax symptomatic infections were more infectious to mosquitoes (infecting 46.5% of mosquitoes, 307/660) compared to asymptomatic microscopy-detected (infecting 12.0% of mosquitoes, 80/667; P = .005) and PCR-detected infections (infecting 0.8% of mosquitoes, 6/744; P < .001). Adjusting for population prevalence, symptomatic, asymptomatic microscopy-detected, and PCR-detected infections were responsible for 8.0%, 76.2%, and 15.8% of the infectious reservoir for P. vivax, respectively. For P. falciparum, mosquito infections were sparser and also predominantly from asymptomatic infections.Conclusions. In this low-endemic setting aiming for malaria elimination, asymptomatic infections were highly prevalent and responsible for the majority of onward mosquito infections. The early identification and treatment of asymptomatic infections might accelerate elimination efforts.