Rosas-Aguirre Angel, Guzman-Guzman Mitchel, Gamboa Dionicia, Chuquiyauri Raul, Ramirez Roberson, Manrique Paulo, Carrasco-Escobar Gabriel, Puemape Carmen, Llanos-Cuentas Alejandro, Vinetz Joseph M
Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima 31, Peru.
Research Institute of Health and Society (IRSS), Université Catholique de Louvain, 1200, Brussels, Belgium.
Malar J. 2017 Aug 4;16(1):312. doi: 10.1186/s12936-017-1957-y.
Understanding the dynamics of malaria transmission in diverse endemic settings is key for designing and implementing locally adapted and sustainable control and elimination strategies. A parasitological and epidemiological survey was conducted in September-October 2012, as a baseline underlying a 3-year population-based longitudinal cohort study. The aim was to characterize malaria transmission patterns in two contrasting ecological rural sites in the Peruvian Amazon, Lupuna (LUP), a riverine environment, and Cahuide (CAH), associated with road-linked deforestation.
After a full population census, 1941 individuals 3 years and older (829 in LUP, 1112 in CAH) were interviewed, clinically examined and had a blood sample taken for the detection of malaria parasites by microscopy and PCR. Species-specific parasite prevalence was estimated overall and by site. Multivariate logistic regression models assessed risk factors for parasite infection by PCR, while SaTScan detected spatial clusters of PCR-positive individuals within each site. In addition, data from routine malaria surveillance in the period 2009-2012 were obtained.
Parasite prevalence by PCR was higher in CAH than in LUP for Plasmodium vivax (6.2% vs. 3.9%) and for Plasmodium falciparum (2.6% vs. 1.2%). Among PCR-confirmed infections, asymptomatic (Asy) parasite carriers were always more common than symptomatic (Sy) infections for P. vivax (Asy/Sy ratio: 2/1 in LUP and 3.7/1 in CAH) and for P. falciparum (Asy/Sy ratio: 1.3/1 in LUP and 4/1 in CAH). Sub-patent (Spat) infections also predominated over patent (Pat) infections for both species: P. vivax (Spat/Pat ratio: 2.8/1 in LUP and 3.7/1 in CAH) and P. falciparum malaria (Spat/Pat ratio: 1.9/1 in LUP and 26/0 in CAH). For CAH, age, gender and living in a household without electricity were significantly associated with P. vivax infection, while only age and living in a household with electricity was associated with P. falciparum infection. For LUP, only household overcrowding was associated with P. falciparum infection. The spatial analysis only identified well-defined clusters of P. vivax and P. falciparum infected individuals in CAH. Reported malaria incidence indicated that malaria transmission has long occurred in LUP with primarily seasonal patterns, and confirmed a malaria outbreak in CAH since May 2012.
This parasitological and epidemiological baseline assessment demonstrates that malaria transmission and parasite prevalence is heterogeneous in the Peruvian Amazon, and influenced by local socio-demographics and ecological contexts. Riverine and road construction/deforestation contexts must be taken into account in order to carry out effective anti-malaria control and elimination efforts.
了解不同疟疾流行地区的传播动态是设计和实施因地制宜且可持续的控制与消除策略的关键。2012年9月至10月开展了一项寄生虫学和流行病学调查，作为一项为期3年的基于人群的纵向队列研究的基线。目的是描述秘鲁亚马逊地区两个生态环境迥异的农村地区的疟疾传播模式，一个是河滨环境的卢普纳（LUP），另一个是与道路相关的森林砍伐地区卡维德（CAH）。
在进行全面人口普查后，对1941名3岁及以上个体（卢普纳829人，卡维德1112人）进行了访谈、临床检查，并采集血样通过显微镜检查和聚合酶链反应（PCR）检测疟原虫。总体及按地点估计了特定种类疟原虫的流行率。多变量逻辑回归模型评估了PCR检测寄生虫感染的风险因素，而时空扫描（SaTScan）检测了每个地点内PCR阳性个体的空间聚集情况。此外，还获取了2009 - 2012年期间常规疟疾监测的数据。
对于间日疟原虫，通过PCR检测的寄生虫流行率在卡维德高于卢普纳（6.2%对3.9%），对于恶性疟原虫也是如此（2.6%对1.2%）。在PCR确诊的感染中，间日疟原虫无症状（Asy）寄生虫携带者总是比有症状（Sy）感染更为常见（卢普纳的Asy/Sy比率：2/1，卡维德为3.7/1），恶性疟原虫也是如此（卢普纳的Asy/Sy比率：1.3/1，卡维德为4/1）。两种疟原虫的亚临床（Spat）感染也均多于显性（Pat）感染：间日疟原虫（卢普纳的Spat/Pat比率：2.8/1，卡维德为3.7/1）和恶性疟原虫（卢普纳的Spat/Pat比率：1.9/1，卡维德为26/0）。对于卡维德，年龄、性别以及居住在无电家庭与间日疟原虫感染显著相关，而仅年龄和居住在有电家庭与恶性疟原虫感染相关。对于卢普纳，仅家庭过度拥挤与恶性疟原虫感染相关。空间分析仅在卡维德发现了明确的间日疟原虫和恶性疟原虫感染个体聚集区。报告的疟疾发病率表明，卢普纳长期存在疟疾传播，主要呈季节性模式，并证实自2012年5月以来卡维德爆发了疟疾。
这项寄生虫学和流行病学基线评估表明，秘鲁亚马逊地区的疟疾传播和寄生虫流行情况存在异质性，并受当地社会人口统计学和生态环境影响。为了开展有效的抗疟疾控制和消除工作，必须考虑河滨和道路建设/森林砍伐环境。
