Spatial clustering of patent and sub-patent malaria infections in northern Namibia: Implications for surveillance and response strategies for elimination
Spatial clustering of patent and sub-patent malaria infections in northern Namibia: Implications for surveillance and response strategies for elimination
复制标题
DOI：
10.1371/journal.pone.0180845
复制
发表时间：
2017-08-18
期刊：
影响因子：
3.7
通讯作者：
Sturrock, Hugh J. W.
中科院分区：
文献类型：
--
作者：
Smith, Jennifer L.;Auala, Joyce;Sturrock, Hugh J. W.
背景围绕被动发现的疟疾病例进行反应性病例检测（RACD）是识别和治疗疟疾传播热点的一种策略。这项研究调查了未经证实的假设，这种方法的基础上，在低传输设置，感染集群在小scales.MethodsA前瞻性病例对照研究进行了2013年1月和2014年8月之间在Ohangwena和Omusati地区在纳米比亚中北部。对疟疾快速诊断试验（RDT）呈阳性的到卫生机构就诊的患者（指示病例）进行了追踪，并追溯到其家中。所有居住者的指示病例家庭（n = 116户）和周围的家庭（n = 225）进行了筛选，疟原虫感染的快速诊断试验（RDT）和环介导的等温扩增（LAMP），并进行了采访，以确定危险因素。还筛选了一个由286个随机选择的对照家庭组成的对照组，以比较RACD和非RACD家庭及其邻居的感染水平。Logistic回归用于调查索引病例周围的未闭和亚未闭感染的空间聚集，并确定潜在的风险因素，以告知筛查方法并确定风险组。估计的影响，RACD上向前传播的蚊子是使用以前公布的数字的感染率.ResultsPrevalence恶性疟原虫感染的LAMP分别为3.4%，1.4%和0.4%，在索引病例家庭，邻居的索引病例家庭和对照家庭分别;病例家庭与对照家庭的调整优势比为6.1 [95% CI 1.9-19.5]。使用来自Engela的数据，与对照家庭相比，病例的邻居有更高的感染几率[调整OR 5.0 95%CI 1.3-18.9]。RDTs确定的所有感染都是无发热的，RDTs仅确定了一小部分病例（n = 7; 17%）和对照（0%）社区的感染。根据专利和专利下的传染性公布的估计，这些结果表明，感染错过了RDTs在RACD将允许50-71%的感染蚊子发生在这个setting.ConclusionMalaria感染集群周围被动检测的情况下。大多数感染是无症状的，其密度低于目前快速诊断试验的检测限。使用标准RDT的RACD不太可能检测到足够的疟疾感染，以大幅减少传播。在纳米比亚等低传播环境中，应试验更敏感的实地诊断或重点假定治疗形式，作为减少疟疾传播的战略。
BackgroundReactive case detection (RACD) around passively detected malaria cases is a strategy to identify and treat hotspots of malaria transmission. This study investigated the unproven assumption on which this approach is based, that in low transmission settings, infections cluster over small scales.MethodsA prospective case-control study was conducted between January 2013 and August 2014 in Ohangwena and Omusati regions in north central Namibia. Patients attending health facilities who tested positive by malaria rapid diagnostic test (RDT) (index cases) were traced back to their home. All occupants of index case households (n = 116 households) and surrounding households (n = 225) were screened for Plasmodium infection with a rapid diagnostic test (RDT) and loop mediated isothermal amplification (LAMP) and interviewed to identify risk factors. A comparison group of 286 randomly-selected control households was also screened, to compare infection levels of RACD and non-RACD households and their neighbours. Logistic regression was used to investigate spatial clustering of patent and subpatent infections around index cases and to identify potential risk factors that would inform screening approaches and identify risk groups. Estimates of the impact of RACD on onward transmission to mosquitoes was made using previously published figures of infection rates.ResultsPrevalence of Plasmodium falciparum infection by LAMP was 3.4%, 1.4% and 0.4% in index-case households, neighbors of index case households and control households respectively; adjusted odds ratio 6.1 [95% CI 1.9-19.5] comparing case households versus control households. Using data from Engela, neighbors of cases had higher odds of infection [adjusted OR 5.0 95% CI 1.3-18.9] compared to control households. All infections identified by RDTs were afebrile and RDTs identified only a small proportion of infections in case (n = 7; 17%) and control (0%) neighborhoods. Based on published estimates of patent and sub-patent infectiousness, these results suggest that infections missed by RDTs during RACD would allow 50-71% of infections to mosquitoes to occur in this setting.ConclusionMalaria infections cluster around passively detected cases. The majority of infections are asymptomatic and of densities below the limit of detection of current RDTs. RACD using standard RDTs are unlikely to detect enough malaria infections to dramatically reduce transmission. In low transmission settings such as Namibia more sensitive field diagnostics or forms of focal presumptive treatment should be tested as strategies to reduce malaria transmission.