Seyoum Dinberu, Kifle Yehenew Getachew, Rondeau Virginie, Yewhalaw Delenasaw, Duchateau Luc, Rosas-Aguirre Angel, Speybroeck Niko
Institute of Health and Society (IRSS), Université catholique de Louvain, Brussels, Belgium.
Department of Statistics, Natural Science College, Jimma University, Jimma, Ethiopia.
Malar J. 2016 Apr 14;15:208. doi: 10.1186/s12936-016-1253-2.
The identification of epidemiological pattern of infection with Plasmodium falciparum and Plasmodium vivax in malaria-endemic area, where multiple episodes are common, is important for intervention programmes.
A longitudinal cohort study based on weekly house-to-house visits was conducted between July 2008 and June 2010 in 2040 children less than 10 years of age, living nearby the Gilgel-Gibe hydroelectric power dam reservoir in order to determine factors associated with increased P. vivax and P. falciparum incidence. Two types of multivariate frailty models were applied (using time-to-first malaria episode data and time-to-recurrent malaria episode data), allowing the estimation of adjusted hazard ratios (AHR) of potential risk factors (gender, age, proximity to the dam reservoir, and season) for species-specific malaria incidence.
Of 2040 children in 96 weeks of follow up, 864 children experienced at least one malaria episode: 685 due to P. falciparum in 548 children, and 385 due to P. vivax in 316 children. Plasmodium vivax and P. falciparum malaria incidence rates were 8.2 (95 % CI: 7.3-9.1) and 14.6 (95 % CI: 13.4-15.6) per 1000 children per month, respectively. According to the time-to-recurrent event models, children aged ≥7 years had a lower risk of presenting P. vivax episodes (AHR = 0.6; 95 % CI: 0.4-0.9), but a higher risk of P. falciparum episodes, when compared with children under ≤3 years (AHR = 1.2; 95 % CI: 1.1-1.6). In addition, P. vivax (AHR = 2.7; 95 % CI: 2.2-3.5) and P. falciparum (AHR = 16.9; 95 % CI: 14.3-20.2) episodes were respectively 2.7 and 16.9 times more frequent in the dry season than in the long rainy season.
The analysis of all malaria episodes (first and recurrent episodes) in the malaria cohort suggests different species-specific patterns of malaria disease in children, with mild seasonality in the incidence of P. vivax episodes mostly observed in younger age groups, and with marked seasonality in the incidence of P. falciparum episodes mainly seen in older children.
在疟疾流行地区，恶性疟原虫和间日疟原虫感染的流行病学模式识别对于干预项目很重要，在这些地区多次发病很常见。
2008年7月至2010年6月期间，对居住在吉尔吉尔-吉贝水电大坝水库附近的2040名10岁以下儿童进行了一项基于每周逐户走访的纵向队列研究，以确定与间日疟原虫和恶性疟原虫发病率增加相关的因素。应用了两种多变量脆弱模型（使用首次疟疾发作时间数据和复发性疟疾发作时间数据），从而能够估计特定物种疟疾发病率的潜在风险因素（性别、年龄、与大坝水库的距离和季节）的调整风险比（AHR）。
在2040名儿童96周的随访中，864名儿童经历了至少一次疟疾发作：548名儿童因恶性疟原虫发作685次，316名儿童因间日疟原虫发作385次。间日疟原虫和恶性疟原虫的疟疾发病率分别为每1000名儿童每月8.2（95%CI：7.3 - 9.1）和14.6（95%CI：13.4 - 15.6）。根据复发性事件模型，与3岁及以下儿童相比，7岁及以上儿童发生间日疟原虫发作的风险较低（AHR = 0.6；95%CI：0.4 - 0.9），但发生恶性疟原虫发作的风险较高（AHR = 1.2；95%CI：1.1 - 1.6）。此外，间日疟原虫（AHR = 2.7；95%CI：2.2 - 3.5）和恶性疟原虫（AHR = 16.9；95%CI：14.3 - 20.2）发作在旱季分别比长雨季频繁2.7倍和16.9倍。
对疟疾队列中所有疟疾发作（首次和复发性发作）的分析表明，儿童疟疾疾病存在不同的物种特异性模式，间日疟原虫发作发病率的季节性在较年轻年龄组中大多较轻，而恶性疟原虫发作发病率的季节性在较大儿童中较为明显。
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