Program in Public Health, College of Health Sciences, University of California, Irvine, CA 92697-4050, USA.
Malar J. 2010 Mar 3;9:67. doi: 10.1186/1475-2875-9-67.
Interest in indoor residual spray (IRS) has been rekindled in recent years, as it is increasingly considered to be a key component of integrated malaria management. Regular spraying of each human dwelling becomes less and less practical as the control area increases. Where malaria transmission is concentrated around focal points, however, targeted IRS may pose a feasible alternative to mass spraying. Here, the impact of targeted IRS was assessed in the highlands of western Kenya.
Indoor residual spray using lambda-cyhalothrin insecticide was carried out during the last week of April 2005 in 1,100 targeted houses, located in the valley bottom areas of Iguhu village, Kakamega district of western Kenya. Although the uphill areas are more densely populated, valleys are believed to be malaria transmission hotspots. The aim of the study was to measurably reduce the vector density and malaria transmission in uphill areas by focusing control on these hotspots. A cohort of 1,058 children from 1-5 yrs of age was randomly selected from a 4 km by 6 km study area for the baseline malaria prevalence survey after pre-clearing malaria infections during the third week of April 2005, and the prevalence of Plasmodium infections was tested bi-weekly. Seasonal changes in mosquito densities 12 months before the IRS and 12 months after the IRS was monitored quarterly based on 300 randomly selected houses. Monthly parasitological surveys were also carried out in the same area with 129-661 randomly selected school children of age 6-13 yrs.
The result of monthly parasitological surveys indicated that malaria prevalence in school children was reduced by 64.4% in the intervention valley area and by 46.3% in the intervention uphill area after 12 months of follow-ups in contrast to nonintervention areas (valley or uphill). The cohort study showed an average of 4.5% fewer new infections biweekly in the intervention valley compare to nonintervention valley and the relative reduction in incidence rate by week 14 was 65.4%. The relative reduction in incidence rate in intervention uphill by week 14 was 46.4%. Anopheles gambiae densities were reduced by 96.8% and 51.6% in the intervention valley and intervention uphill, respectively, and Anopheles funestus densities were reduced by 85.3% and 69.2% in the intervention valley and intervention uphill, respectively.
Vector control had significant indirect impact on the densely populated uphill areas when IRS was targeted to the high-risk valleys. Additionally, the wide-reaching benefits of IRS in reducing vector prevalence and disease incidence was observed for at least six months following spraying, suggesting targeted IRS as an effective tool in malaria control.
近年来，人们对室内滞留喷洒（IRS）重新产生了兴趣，因为它越来越被认为是综合疟疾管理的关键组成部分。随着控制区域的扩大，对每个居住点进行定期喷洒变得越来越不切实际。然而，在疟疾传播集中在焦点地区的情况下，有针对性的 IRS 可能是大规模喷洒的可行替代方案。在这里，评估了靶向 IRS 在肯尼亚西部高地的效果。
在肯尼亚西部卡卡梅加区伊古胡村的山谷底部地区，2005 年 4 月最后一周对 1100 个目标房屋使用 lambda-氯氰菊酯杀虫剂进行了室内滞留喷洒。尽管上坡地区人口密度更高，但山谷被认为是疟疾传播的热点。该研究的目的是通过将控制集中在这些热点地区，显著降低上坡地区的媒介密度和疟疾传播。在 2005 年 4 月的第三周清除疟疾感染后，从一个 4 公里乘 6 公里的研究区域中随机选择了 1058 名 1-5 岁的儿童组成队列进行基线疟疾患病率调查，并且每两周测试一次疟原虫感染的患病率。在 IRS 之前的 12 个月和 IRS 之后的 12 个月，根据 300 个随机选择的房屋，每季度监测蚊子密度的季节性变化。还在同一区域进行了每月寄生虫学调查，调查了 129-661 名年龄在 6-13 岁的随机选择的在校学生。
每月寄生虫学调查结果表明，与非干预区（山谷或上坡）相比，12 个月的随访后，干预山谷地区的学童疟疾患病率下降了 64.4%，干预上坡地区下降了 46.3%。队列研究显示，干预山谷地区每两周的新感染平均减少 4.5%，到第 14 周时发病率的相对减少率为 65.4%。干预上坡地区的发病率相对减少率为 46.4%。在干预山谷和干预上坡地区，冈比亚按蚊密度分别减少了 96.8%和 51.6%，恶性按蚊密度分别减少了 85.3%和 69.2%。
当 IRS 针对高风险山谷时，蚊虫控制对人口密集的上坡地区产生了显著的间接影响。此外，IRS 在减少媒介密度和疾病发病率方面的广泛益处至少在喷洒后六个月内仍然存在，这表明靶向 IRS 是疟疾控制的有效工具。
