Damien Georgia Barikissou, Djènontin Armel, Chaffa Evelyne, Yamadjako Sandra, Drame Papa Makhtar, Ndille Emmanuel Elanga, Henry Marie-Claire, Corbel Vincent, Remoué Franck, Rogier Christophe
IRD-UMR MIVEGEC (IRD224-CNRS5290-Universités Montpellier 1 et 2), Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin.
Laboratoire Evolution, Biodiversité des Arthropodes et Assainissement, Faculté des Sciences et Techniques, Université d'Abomey-Calavi, Abomey-Calavi, Bénin.
Malar J. 2016 Feb 19;15:102. doi: 10.1186/s12936-016-1156-2.
In a context of large-scale implementation of malaria vector control tools, such as the distribution of long-lasting insecticide nets (LLIN), it is necessary to regularly assess whether strategies are progressing as expected and then evaluate their effectiveness. The present study used the case-control approach to evaluate the effectiveness of LLIN 42 months after national wide distribution. This study design offers an alternative to cohort study and randomized control trial as it permits to avoid many ethical issues inherent to them.
From April to August 2011, a case-control study was conducted in two health districts in Benin; Ouidah-Kpomasse-Tori (OKT) in the south and Djougou-Copargo-Ouake (DCO) in the north. Children aged 0-60 months randomly selected from community were included. Cases were children with a high axillary temperature (≥37.5 °C) or a reported history of fever during the last 48 h with a positive rapid diagnostic test (RDT). Controls were children with neither fever nor signs suggesting malaria with a negative RDT. The necessary sample size was at least 396 cases and 1188 controls from each site. The main exposure variable was "sleeping every night under an LLIN for the 2 weeks before the survey" (SL). The protective effectiveness (PE) of LLIN was calculated as PE = 1 - odds ratio.
The declared SL range was low, with 17.0 and 27.5 % in cases and controls in the OKT area, and 44.9 and 56.5 % in cases and controls, in the DCO area, respectively. The declared SL conferred 40.5 % (95 % CI 22.2-54.5 %) and 55.5 % (95 % CI 28.2-72.4 %) protection against uncomplicated malaria in the OKT and the DCO areas, respectively. Significant differences in PE were observed according to the mother's education level.
In the context of a mass distribution of LLIN, their use still conferred protection in up to 55 % against the occurrence of clinical malaria cases in children. Social factors, the poor use and the poor condition of an LLIN can be in disfavour with its effectiveness. In areas, where LLIN coverage is assumed to be universal or targeted at high-risk populations, case-control studies should be regularly conducted to monitor the effectiveness of LLIN. The findings will help National Malaria Control Programme and their partners to improve the quality of malaria control according to the particularity of each area or region as far as possible.
在大规模实施疟疾媒介控制工具（如分发长效驱虫蚊帐）的背景下，有必要定期评估策略是否按预期推进，然后评估其有效性。本研究采用病例对照方法评估全国范围内分发长效驱虫蚊帐42个月后的有效性。这种研究设计为队列研究和随机对照试验提供了一种替代方案，因为它可以避免它们固有的许多伦理问题。
2011年4月至8月，在贝宁的两个卫生区进行了一项病例对照研究；南部的维达-科波马塞-托里（OKT）和北部的朱古-科帕尔戈-瓦克（DCO）。纳入从社区中随机选取的0至60个月大的儿童。病例为腋窝温度高（≥37.5°C）或在过去48小时内有发热报告且快速诊断检测（RDT）呈阳性的儿童。对照为既无发热也无疟疾迹象且RDT呈阴性的儿童。每个地点所需的样本量至少为396例病例和1188例对照。主要暴露变量是“在调查前2周每晚睡在长效驱虫蚊帐下”（SL）。长效驱虫蚊帐的保护效果（PE）计算为PE = 1 - 比值比。
宣称的SL范围较低，OKT地区病例和对照中分别为17.0%和27.5%，DCO地区病例和对照中分别为44.9%和56.5%。宣称的SL在OKT地区和DCO地区分别对非复杂性疟疾提供了40.5%（95%CI 22.2 - 54.5%）和55.5%（95%CI 28.2 - 72.4%）的保护。根据母亲的教育水平观察到PE存在显著差异。
在大规模分发长效驱虫蚊帐的背景下，其使用对儿童临床疟疾病例的发生仍提供高达55%的保护。社会因素、长效驱虫蚊帐的使用不佳和状况不佳可能不利于其有效性。在假定长效驱虫蚊帐覆盖率普遍或针对高危人群的地区，应定期进行病例对照研究以监测长效驱虫蚊帐的有效性。研究结果将有助于国家疟疾控制规划及其合作伙伴尽可能根据每个地区或区域的特殊性提高疟疾控制质量。
