National Dengue Control Unit, Ministry of Health, Sri Lanka.
Department of Clinical Medicine, Faculty of Medicine, University of Colombo, Sri Lanka.
Trop Med Int Health. 2018 Feb;23(2):229-235. doi: 10.1111/tmi.13015. Epub 2017 Dec 7.
The annual incidence of dengue has been increasing over the last few years in Sri Lanka with seasonal epidemics. Biological control of the vector has not been part of the integrated vector control implemented by the public health authorities of Sri Lanka so far. This pilot study assessed the effectiveness of using Bacillus thuringiensis israelensis (Bti) spray to control the Aedes mosquito vector population density.
Prospective controlled effectiveness study in three administrative divisions of Colombo. Study areas were selected from urban, semiurban and rural administrative divisions within the district, and they were compared with two matching controls from the same division. Test areas received three cycles of Bti spraying 1 month apart. Control areas were not sprayed with Bti. Ovitrap and larval indices were calculated at baseline and 2 weeks after each spray cycle.
There was a significant improvement in the adult vector population (ovitrap index) in the test areas after three spray cycles, but this effect had disappeared after 8 weeks (no residual effect). There was no consistent positive impact on larval indices (premise, container and Breteau indices) after each spray cycle.
Bti might have a moderate impact on adult vector populations mediated via transient reductions in larval populations. However, this effect is not sustained probably due to rapid re-infestation. Bti spray, if implemented, can only play a supplementary role to other vector control methods.
在过去几年中，斯里兰卡的登革热发病率呈上升趋势，并伴有季节性流行。生物防治媒介一直未被纳入斯里兰卡公共卫生当局实施的综合病媒控制措施中。本试点研究评估了使用苏云金芽孢杆菌以色列亚种（Bti）喷雾来控制埃及伊蚊媒介种群密度的效果。
在科伦坡的三个行政区进行前瞻性对照效果研究。研究区域选自该地区的城市、半城市和农村行政区，并与来自同一行政区的两个匹配对照区域进行比较。试验区每间隔 1 个月接受 3 次 Bti 喷雾。对照区不喷洒 Bti。在基线和每个喷雾周期结束后 2 周计算诱卵器和幼虫指数。
经过 3 次喷雾后，试验区的成年病媒种群（诱卵器指数）有显著改善，但 8 周后这种效果消失（无残留效果）。每次喷雾后，幼虫指数（前提、容器和布雷特指数）均无一致的积极影响。
Bti 可能通过暂时降低幼虫数量对成年病媒种群产生中等影响。然而，由于快速重新感染，这种效果无法持续。Bti 喷雾，如果实施，只能作为其他病媒控制方法的补充手段。
