Kirby Matthew J, Green Clare, Milligan Paul M, Sismanidis Charalambos, Jasseh Momadou, Conway David J, Lindsay Steven W
School of Biological and Biomedical Sciences, Durham University, Science Laboratories, South Road, Durham DH1 3LE, UK.
Malar J. 2008 Jan 7;7:2. doi: 10.1186/1475-2875-7-2.
In the pre-intervention year of a randomized controlled trial investigating the protective effects of house screening against malaria-transmitting vectors, a multi-factorial risk factor analysis study was used to identify factors that influence mosquito house entry.
Mosquitoes were sampled using CDC light traps in 976 houses, each on one night, in Farafenni town and surrounding villages during the malaria-transmission season in The Gambia. Catches from individual houses were both (a) left unadjusted and (b) adjusted relative to the number of mosquitoes caught in four sentinel houses that were operated nightly throughout the period, to allow for night-to-night variation. Houses were characterized by location, architecture, human occupancy and their mosquito control activities, and the number and type of domestic animals within the compound.
106,536 mosquitoes were caught, of which 55% were Anopheles gambiae sensu lato, the major malaria vectors in the region. There were seven fold higher numbers of An. gambiae s.l. in the villages (geometric mean per trap night = 43.7, 95% confidence intervals, CIs = 39.5-48.4) than in Farafenni town (6.3, 5.7-7.2) and significant variation between residential blocks (p < 0.001). A negative binomial multivariate model performed equally well using unadjusted or adjusted trap data. Using the unadjusted data the presence of nuisance mosquitoes was reduced if the house was located in the town (odds ratio, OR = 0.11, 95% CIs = 0.09-0.13), the eaves were closed (OR = 0.71, 0.60-0.85), a horse was tethered near the house (OR = 0.77, 0.73-0.82), and churai, a local incense, was burned in the room at night (OR = 0.56, 0.47-0.66). Mosquito numbers increased per additional person in the house (OR = 1.04, 1.02-1.06) or trapping room (OR = 1.19, 1.13-1.25) and when the walls were made of mud blocks compared with concrete (OR = 1.44, 1.10-1.87).
This study demonstrates that the risk of malaria transmission is greatest in rural areas, where large numbers of people sleep in houses made of mud blocks, where the eaves are open, horses are not tethered nearby and where churai is not burnt at night. These factors need to be considered in the design and analysis of intervention studies designed to reduce malaria transmission in The Gambia and other parts of sub-Saharan Africa.
在一项调查房屋筛查对疟疾传播媒介保护作用的随机对照试验的干预前一年，开展了一项多因素风险因素分析研究，以确定影响蚊子进入房屋的因素。
在冈比亚疟疾传播季节，使用疾控中心诱蚊灯在法拉芬尼镇及周边村庄的976所房屋中各捕捉一晚蚊子。各房屋的捕获量（a）未作调整，（b）相对于在此期间每晚运行的4所哨兵房屋中捕获的蚊子数量进行了调整，以考虑夜间差异。房屋的特征包括位置、建筑结构、居住情况及其蚊虫控制活动，以及院子里家畜的数量和种类。
共捕获106,536只蚊子，其中55%为冈比亚按蚊复合组，是该地区主要的疟疾传播媒介。村庄中冈比亚按蚊复合组的数量比法拉芬尼镇高7倍（每诱捕器每晚几何平均数 = 43.7，95%置信区间，CI = 39. – 4 – 48.4），不同住宅区之间存在显著差异（p < 0.001）。使用未调整或调整后的诱捕数据，负二项式多变量模型表现同样良好。使用未调整数据时，如果房屋位于城镇（优势比，OR = 0.11，95% CI = 0.09 – 0.13）、屋檐封闭（OR = 0.71，0.60 – 0.85）、房屋附近拴有一匹马（OR = 0.77，0.73 – 0.82）以及夜间在室内燃烧当地香薰“churai”（OR = 0.56，0.47 – 0.66），则骚扰性蚊子的数量会减少。房屋内每增加一人（OR = 1.04，1.02 – 1.06）或诱捕房间内每增加一人（OR = 1.19，1.13 – 1.25），以及墙壁为泥砖而非混凝土时（OR = 1.44，1.10 – 1.87），蚊子数量都会增加。
本研究表明，在农村地区疟疾传播风险最大，那里大量人口睡在泥砖房屋中，屋檐敞开，附近没有拴马，且夜间不燃烧churai。在设计和分析旨在减少冈比亚及撒哈拉以南非洲其他地区疟疾传播的干预研究时，需要考虑这些因素。
