Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (FMT-HVD), Av. Pedro Teixeira, N.25, Dom Pedro, Manaus, Amazonas, CEP: 69040-000, Brazil.
Universidade do Estado do Amazonas (UEA), Av. Djalma Batista, N. 3578, Flores, Manaus, Amazonas, CEP: 69005-010, Brazil.
Parasit Vectors. 2018 Mar 20;11(1):194. doi: 10.1186/s13071-018-2787-7.
Population-based studies conducted in Latin America have shown a high proportion of asymptomatic and submicroscopic malarial infections. Considering efforts aiming at regional elimination, it is important to investigate the role of this asymptomatic reservoir in malaria transmission in peri-urban areas. This study aimed to estimate the prevalence of Plasmodium spp. and gametocyte burden on symptomatic and asymptomatic infections in the Brazilian Amazon.
Two cross-sectional household surveys (CS) were conducted including all inhabitants in a peri-urban area of Manaus, western Amazonas State, Brazil. Malaria parasites were detected by light microscopy (LM) and qPCR. Sexual stages of Plasmodium spp. were detected by LM and RT-qPCR. A total of 4083 participants were enrolled during the two surveys. In CS1, the prevalence of Plasmodium vivax infections was 4.3% (86/2010) by qPCR and 1.6% (32/2010) by LM. Fifty percent (43/86) of P. vivax infected individuals (qPCR) carried P. vivax gametocytes. In CS2, 3.4% (70/2073) of participants had qPCR-detectable P. vivax infections, of which 42.9% (30/70) of infections were gametocyte positive. The P. vivax parasite density was associated with gametocyte carriage (P < 0.001). Sixty-seven percent of P. vivax infected individuals and 53.4% of P. vivax gametocyte carriers were asymptomatic.
This study confirms a substantial proportion of asymptomatic and submicroscopic P. vivax infections in the study area. Most asymptomatic individuals carried gametocytes and presented low asexual parasitemia. This reservoir actively contributes to malaria transmission in the Brazilian Amazon, underscoring a need to implement more efficient control and elimination strategies.
拉丁美洲的基于人群的研究表明，无症状和亚显微疟原虫感染的比例很高。考虑到旨在实现区域消除的努力，研究这种无症状储存库在城市周边地区疟疾传播中的作用非常重要。本研究旨在估计巴西亚马逊地区有症状和无症状感染中疟原虫 spp. 和配子体负担的流行率。
在巴西亚马逊西部亚马孙州玛瑙斯市的城市周边地区进行了两项横断面家庭调查（CS），包括所有居民。通过光镜（LM）和 qPCR 检测疟原虫。通过 LM 和 RT-qPCR 检测疟原虫的有性阶段。在两次调查中，共有 4083 名参与者被纳入。在 CS1 中，qPCR 检测到间日疟原虫感染的流行率为 4.3%（86/2010），LM 为 1.6%（32/2010）。50%（43/86）的间日疟原虫感染个体（qPCR）携带间日疟原虫配子体。在 CS2 中，2073 名参与者中有 3.4%（70/2073）通过 qPCR 检测到间日疟原虫感染，其中 42.9%（30/70）的感染为配子体阳性。间日疟原虫寄生虫密度与配子体携带有关（P<0.001）。67%的间日疟原虫感染个体和 53.4%的间日疟原虫配子体携带者无症状。
本研究证实，在研究区域存在相当比例的无症状和亚显微间日疟原虫感染。大多数无症状个体携带配子体，且无性寄生虫血症水平较低。这种储存库积极促进了巴西亚马逊地区的疟疾传播，强调需要实施更有效的控制和消除策略。
