Identification and characterization of areas of high and low risk for asymptomatic malaria infections at sub-village level in Ratanakiri, Cambodia
Identification and characterization of areas of high and low risk for asymptomatic malaria infections at sub-village level in Ratanakiri, Cambodia
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DOI：
10.1186/s12936-017-2169-1
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发表时间：
2018-01-15
期刊：
影响因子：
3
通讯作者：
Sluydts, Vincent
中科院分区：
文献类型：
--
作者：
Durnez, Lies;Pareyn, Myrthe;Sluydts, Vincent
背景资料：消灭疟疾需要集中开展活动，查明剩余的传播疫源地，并加紧努力消灭位于所谓“疟疾热点”的最后几个感染病例。以前关于疟疾传播热点特征的工作主要集中在恶性疟疾，特别是有症状的病例，而疟疾宿主预计将主要集中在传播率低时的无症状人群中。对于间日疟原虫，在确定传播热点方面所做的努力较少。本研究的主要目的是揭示微流行病学机制的聚集性疟疾感染在一个子村一级，基于地理或行为features.Methods：进行横断面调查，在三个村庄内的最高疟疾流行的柬埔寨省。调查是在旱季进行的，预计此时疟疾发病率较低，居住在人口中无症状的部分。对家庭的村庄和田间位置进行了地理参考，从尽可能多的居民中采集了血液样本，并进行了简短的问卷调查，以探索个人风险因素。结果：1792例无症状疟疾带菌者中，共检出1540例（86%），其中1540例为典型病例。疟原虫DNA检出率为8.4%。间日疟原虫最流行（5.5%），其次是三日疟原虫（2.1%）和恶性疟原虫（1.6%）。混合感染12例。在三分之二的村庄中，疟疾感染风险高低的地理聚集现象明显存在。与感染相关的聚集位置和风险因素在寄生虫物种之间存在差异。年龄是合并疟原虫感染的重要危险因素，而晚上看电视与间日疟原虫感染几率增加相关[ OR（CI）：1.86（0.95-3.64）]，蚊帐使用与恶性疟原虫感染几率降低相关[OR（CI）：0.25（0.077-0.80）].结论：疟疾带菌者的聚集具有疟疾种类特异性，而且往往位于偏远的村庄中心以外。因此，在微观流行病学层面，疟疾不是一种单一的疾病。进一步揭示疟疾的微流行病学，可使方案管理人员确定可能有助于在特定热点地区阻止传播的干预措施。
Background: Malaria elimination needs a concentration of activities towards identification of residual transmission foci and intensification of efforts to eliminate the last few infections, located in so-called 'malaria hotspots'. Previous work on characterizing malaria transmission hotspots has mainly focused on falciparum malaria and especially on symptomatic cases, while the malaria reservoir is expected to be mainly concentrated in the asymptomatic human population when transmission is low. For Plasmodium vivax, there has been less effort in identifying transmission hotspots. The main aim of this study was to uncover micro-epidemiological mechanisms of clustering of malaria infections at a sub-village level, based on geographical or behavioural features.Methods: A cross-sectional survey was performed in three villages within the highest malaria endemic province of Cambodia. The survey took place in the dry season, when the malaria reservoir is expected to be low and residing in the asymptomatic part of the population. Village and field locations of households were georeferenced, blood samples were taken from as many residents as possible and a short questionnaire probing for individual risk factors was taken. Asymptomatic malaria carriers were detected by PCR, and geographical clustering analysis (SaTScan) as well as risk factor analysis were performed.Results: A total of 1540 out of 1792 (86%) individuals were sampled. Plasmodial DNA was detected in 129 individuals (8.4%). P. vivax was most prevalent (5.5%) followed by Plasmodium malariae (2.1%) and Plasmodium falciparum (1.6%). Mixed infection occurred in 12 individuals. In two out of three villages geographical clustering of high and low malaria infection risk was clearly present. Cluster location and risk factors associated with the infection differed between the parasite species. Age was an important risk factor for the combined Plasmodium infections, while watching television at evenings was associated with increased odds of P. vivax infections [ OR (CI): 1.86 (0.95-3.64)] and bed net use was associated with reduced odds of P. falciparum infections [OR (CI): 0.25 (0.077-0.80)].Conclusions: Clusters of malaria carriers were malaria species specific and often located remotely, outside village centres. As such, at micro-epidemiological level, malaria is not a single disease. Further unravelling the micro-epidemiology of malaria can enable programme managers to define the interventions likely to contribute to halt transmission in a particular hotspot location.