Effect of Transmission Setting and Mixed Species Infections on Clinical Measures of Malaria in Malawi
Effect of Transmission Setting and Mixed Species Infections on Clinical Measures of Malaria in Malawi
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DOI：
10.1371/journal.pone.0002775
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发表时间：
2008-07-23
期刊：
影响因子：
3.7
通讯作者：
Molyneux, Malcolm E.
中科院分区：
文献类型：
--
作者：
Bruce, Marian C.;Macheso, Allan;Molyneux, Malcolm E.
背景：在疟疾流行地区，人们通常感染多种疟疾寄生虫，但这些疟原虫合并感染的临床影响尚不清楚。流行地区之间传播季节性和传播强度的差异被认为是决定多物种共感染影响的重要因素。主要发现：为了调查多物种感染对疟疾临床措施的影响，我们于2002年在马拉维进行了一项横断面社区调查。我们收集了2918名年龄在0 ~ 6个月的参与者的临床和寄生虫学资料，并采用问卷调查方法测量疟疾发病率。我们通过比较三个地区：多年生传播（PT）、高强度季节性传播（HIST）和低强度季节性传播（LIST），研究了传播的季节性和强度对发烧、发烧史、血红蛋白浓度（[Hb]）和寄生虫密度的影响。这些区域是使用PCR流行数据和空间和地理气候测量的多级建模来定义的。3种疟原虫（恶性疟原虫、疟疾疟原虫和卵形疟原虫）随机分布在LIST和PT地区的所有儿童中，而非成人中。与其他两个地区相比，HIST地区儿童平均寄生虫密度较低。PT地区混合种感染的平均寄生虫密度低于单种感染。不同传播区域之间的发烧率相似，并且不受混合物种感染的影响。发热史与单一物种感染有关，但仅在HIST地区。与季节性传播相比，平均[Hb]降低和贫血增加与常年传播有关。HIST地区混合种感染儿童Hb较高。结论：我们的研究表明，共同感染疟原虫的物种之间的相互作用可能对疟疾的某些临床结果具有保护作用，但这取决于疟疾传播的季节性和强度。
Background: In malaria endemic regions people are commonly infected with multiple species of malaria parasites but the clinical impact of these Plasmodium co-infections is unclear. Differences in transmission seasonality and transmission intensity between endemic regions have been suggested as important factors in determining the effect of multiple species co-infections.Principal Findings: In order to investigate the impact of multiple-species infections on clinical measures of malaria we carried out a cross-sectional community survey in Malawi, in 2002. We collected clinical and parasitological data from 2918 participants aged >6 months, and applied a questionnaire to measure malaria morbidity. We examined the effect of transmission seasonality and intensity on fever, history of fever, haemoglobin concentration ([Hb]) and parasite density, by comparing three regions: perennial transmission (PT), high intensity seasonal transmission (HIST) and low intensity seasonal transmission (LIST). These regions were defined using multi-level modelling of PCR prevalence data and spatial and geoclimatic measures. The three Plasmodium species (P. falciparum, P. malariae and P. ovale) were randomly distributed amongst all children but not adults in the LIST and PT regions. Mean parasite density in children was lower in the HIST compared with the other two regions. Mixed species infections had lower mean parasite density compared with single species infections in the PT region. Fever rates were similar between transmission regions and were unaffected by mixed species infections. A history of fever was associated with single species infections but only in the HIST region. Reduced mean [Hb] and increased anaemia was associated with perennial transmission compared to seasonal transmission. Children with mixed species infections had higher [Hb] in the HIST region.Conclusions: Our study suggests that the interaction of Plasmodium co-infecting species can have protective effects against some clinical outcomes of malaria but that this is dependent on the seasonality and intensity of malaria transmission.