Epidemiology of Malaria in the Peruvian and Brazilian Amazon

巴西和秘鲁这两个疟疾流行国家的机构正在与美国的一个领先研究小组合作，长期目标是提供可转化为亚马逊地区疟疾控制的有效公共卫生干预措施的科学证据。为了确定无症状寄生虫携带是否是该地区疟疾传播的主要因素，我们的目标是：(A)估计亚马逊地区农村地区无症状疟疾寄生虫携带的流行率、发病率和危险因素；(B)估计配子体携带配子体的流行率、发生率、平均持续时间和风险因素；(C)比较有症状和无症状的配子体携带者实验感染野生捕获的当地媒介的能力；(D)前瞻性地比较居住在同一社区的无症状寄生虫携带者和未感染的对照组随后临床疟疾的风险，并确定这些发作是由于持续的寄生虫谱系还是由于新的感染；以及(E)测试寄主内不同的寄生虫克隆的竞争是否有助于提高寄生虫的毒力、更大的疾病风险和增加配子体的产量。这些目标将通过使用统一的临床和实验室方案的人口调查，在亚马逊地区的三个流行病学多样化的环境中实现：(A)巴西疟疾流行的典型农业定居点，(B)最近暴露于疟疾流行的秘鲁城郊村庄，以及(C)秘鲁因间日疟原虫而暴发疟疾的金矿飞地。实地的临床和流行病学分析将辅之以免疫学参数的测量、广泛的寄生虫基因分型和通过膜喂养试验对蚊子的实验感染，从而为亚马孙盆地无症状寄生虫携带对公共卫生的意义提供独特的多学科视角。至关重要的是，实地七年积极监测疟疾的基础设施和数据将为这项提议的病媒生物学和发病机制部分以及在亚马逊地区实施未来的疟疾疫苗试验奠定基础。

Institutions based in two malaria-endemic countries, Brazil and Peru, are partnering with a leading research group in the USA with the long-term goal of providing scientific evidence that can be translated into effective public health interventions for malaria control in Amazonia. To determine whether asymptomatic parasite carriage is a major contributor to malaria transmission across the region, we aim: (a) to estimate the prevalence, incidence and risk factors for asymptomatic malaria parasite carriage in rural Amazonia; (b) to estimate the prevalence, incidence, average duration and risk factors for gametocyte carriage; (c) to compare the ability of symptomatic and asymptomatic carriers of gametocytes to experimentally infect wild caught local vectors; (d) to compare prospectively the risk of subsequent clinical malaria among asymptomatic parasite carriers and non-infected controls living in the same communities and to determine whether these episodes are due to persistent parasite lineages or to new infections; and (e) to test whether intra-host competition of genetically distinct parasite clones contributes to increased parasite virulence, greater risk of disease, and increased gametocyte production. These aims will be achieved with population based surveys, using uniformized clinical and laboratory protocols, in three epidemiologically diverse Amazonian settings: (a) a typical agricultural settlement with endemic malaria transmission in Brazil, (b) periurban villages in Peru that became recently exposed to epidemic malaria, and (c) gold-mining enclaves in Peru with explosive malaria outbreaks due to P. vivax. The field-based clinical and epidemiological analysis will be complemented with measurements of immunological parameters, extensive parasite genotyping and experimental infections of mosquitoes through membrane-feeding assays, providing a unique multidisciplinary perspective on the public health significance of asymptomatic parasite carriage in the Amazon Basin. Of crucial importance, the infrastructure and the data resulting of seven years of active malaria surveillance in the field sites will establish the bases for the vector biology and pathogenesis components of this proposal and for implementing future malaria vaccine trials in the Amazon region.