Spatio-Temporal Dynamics of Asymptomatic Malaria: Bridging the Gap Between Annual Malaria Resurgences in a Sahelian Environment
Spatio-Temporal Dynamics of Asymptomatic Malaria: Bridging the Gap Between Annual Malaria Resurgences in a Sahelian Environment
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DOI：
10.4269/ajtmh.17-0074
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发表时间：
2017-01-01
影响因子：
3.3
通讯作者：
Gaudart, Jean
中科院分区：
文献类型：
--
作者：
Coulibaly, Drissa;Travassos, Mark A.;Gaudart, Jean
在季节性疟疾传播地区，据推测，在旱季结束时，疟疾感染的发病率接近于零。在此期间，无症状个体可能构成一个主要的寄生虫宿主。我们对马里一个城镇的临床疟疾和无症状寄生虫病的时空分布进行了纵向分析，以突出这些疟疾传播动态。对2009-2014年期间随访的300名农村儿童进行了光谱分析，确定了疟疾与降雨之间的周期性和相移。确定了临床发作或携带的空间风险集群。进行了巢式病例对照研究，以评估寄生虫携带因素。疟疾感染全年持续存在，有季节性高峰。高传播期开始于降雨后2-3个月。镇中心临床疟疾低风险聚集性病例在高传播期和低传播期持续存在。在2009-2014年期间，集群的位置每年都没有变化。即使在低传播期，无症状和配子体携带也持续存在。在高传播期，无症状病例与临床病例之比约为0.5，但在低传播期则高出5倍。以往高传播期的临床发作是无症状传播的保护因素，但在以往高传播期携带无症状的寄生虫是无症状传播的危险因素。稳定的疟疾传播与旱季持续的无症状携带有关。控制策略应针对持续的低水平寄生虫病聚集，以阻断传播。
In areas of seasonal malaria transmission, the incidence rate of malaria infection is presumed to be near zero at the end of the dry season. Asymptomatic individuals may constitute a major parasite reservoir during this time. We conducted a longitudinal analysis of the spatio-temporal distribution of clinical malaria and asymptomatic parasitemia over time in a Malian town to highlight these malaria transmission dynamics. For a cohort of 300 rural children followed over 2009-2014, periodicity and phase shift between malaria and rainfall were determined by spectral analysis. Spatial risk clusters of clinical episodes or carriage were identified. A nested-case-control study was conducted to assess the parasite carriage factors. Malaria infection persisted over the entire year with seasonal peaks. High transmission periods began 2-3 months after the rains began. A cluster with a low risk of clinical malaria in the town center persisted in high and low transmission periods. Throughout 2009-2014, cluster locations did not vary from year to year. Asymptomatic and gametocyte carriage were persistent, even during low transmission periods. For high transmission periods, the ratio of asymptomatic to clinical cases was approximately 0.5, but was five times higher during low transmission periods. Clinical episodes at previous high transmission periods were a protective factor for asymptomatic carriage, but carrying parasites without symptoms at a previous high transmission period was a risk factor for asymptomatic carriage. Stable malaria transmission was associated with sustained asymptomatic carriage during dry seasons. Control strategies should target persistent low-level parasitemia clusters to interrupt transmission.