在埃塞俄比亚的低流行地区环境中，症状性和无症状性间日疟原虫和恶性疟原虫感染对感染源的相对贡献。

The Relative Contribution of Symptomatic and Asymptomatic Plasmodium vivax and Plasmodium falciparum Infections to the Infectious Reservoir in a Low-Endemic Setting in Ethiopia.

机构信息

Radboud Institute for Health Sciences, Radboud University Medical Centre, Nijmegen, The Netherlands.

Armauer Hansen Research Institute, Addis Ababa University, Ethiopia.

出版信息

Clin Infect Dis. 2018 Jun 1;66(12):1883-1891. doi: 10.1093/cid/cix1123.

DOI:10.1093/cid/cix1123

PMID:29304258

Abstract

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 (ρ = 0.63; P < .001) but not for P. falciparum (ρ = 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.

摘要

背景

在低流行地区，大多数间日疟原虫和恶性疟原虫感染为无症状感染。目前尚不清楚与临床疟疾病例相比，这些感染对感染源的相对贡献。

方法

我们使用膜喂食法，以在埃塞俄比亚阿达玛用阿拉伯按蚊（Anopheles arabiensis）来评估被动招募的有症状疟疾患者（n=41）和通过显微镜检测（n=41）及聚合酶链反应（PCR）检测到的社区招募无症状个体（n=82）的感染性。利用疟疾发病率和患病率数据来估计这些人群对感染源的贡献。

结果

总体而言，34.9%（29/83）的间日疟原虫感染和 15.1%（8/53）的恶性疟原虫感染个体感染了≥1 只蚊子。间日疟原虫的蚊感染率与无性体密度呈强相关（ρ=0.63；P<0.001），但恶性疟原虫则无此相关性（ρ=0.06；P=0.770）。与无症状显微镜检测到的感染（感染 12.0%的蚊子，80/667；P=0.005）和 PCR 检测到的感染（感染 0.8%的蚊子，6/744；P<0.001）相比，间日疟原虫有症状感染对蚊子更具传染性（感染 46.5%的蚊子，307/660）。调整人群流行率后，有症状、无症状显微镜检测到和 PCR 检测到的感染分别占间日疟原虫感染源的 8.0%、76.2%和 15.8%。对于恶性疟原虫，蚊子感染较少，且主要来自无症状感染。