How important is the angle of tilt in the WHO cone bioassay?
How important is the angle of tilt in the WHO cone bioassay?
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DOI：
10.1186/s12936-016-1303-9
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发表时间：
2016-04-27
期刊：
影响因子：
3
通讯作者：
Muller, Pie
中科院分区：
文献类型：
--
作者：
Owusu, Henry F.;Muller, Pie
背景：世界卫生组织(WHO)锥体生物测定法在评价长效杀虫蚊帐以及室内残留喷洒中使用的杀虫剂的效果方面发挥着不可或缺的作用。这项测试用于各种处理过的基材，如蚊帐、泥浆、水泥和木材。圆锥体设置在应用它的不同设置下假定有各种角度。方法：按照世界卫生组织关于Olyset Plus和Net Protected的指南，对冈比亚按蚊和斯氏按蚊的实验室菌落在4个不同的角度(0度、45度、60度和90度)进行了检测。在清洗了20次蚊帐后，再次进行了测试。结果：蚊子在60度与0度接触蚊帐的时间较长(系数=45.8，95%CI 34.6~55.6，p<；0.001)，在45度(OR 3.3，95%CI 1.7~6.3，p=0.001)、60度(OR 3.1，95%CI 1.7~5.9，p<；)时，蚊子更有可能死亡；0.001)和90度(OR6.0，95%CI1.9-18.5，p=0.002)，而不是0度。结论：测试的角度显著影响蚊子在蚊帐上停留的时间，进而影响死亡率。因此，角度必须被视为分析性能中的一个重要组成部分，并适当地纳入指南。
Background: The World Health Organization (WHO) cone bioassay plays an integral role in the evaluation of the efficacy of long-lasting insecticidal nets as well as insecticides used in indoor residual spraying. The test is used on a variety of treated substrates, such as pieces of bed nets, mud, cement and wood. The cone setup assumes a wide variety of angles under different settings in which it is applied. However, the guidelines provided for the performance of the assay do not specify the angle at which the test must be performed.Methods: Laboratory colonies of Anopheles gambiae Kisumu-1 and Anopheles stephensi STI were tested in the WHO cone bioassay at four different angles (0 degrees, 45 degrees, 60 degrees and 90 degrees) following the WHO guidelines against net pieces of Olyset Plus and Netprotect. The tests were repeated after 20 washes of the nets. Individual mosquitoes were also exposed at 0 degrees and 60 degrees and the amount of time each spent in contact with the net was recorded.Results: Mosquitoes spent more time on the net at 60 degrees as compared to 0 degrees (coefficient = 45.8, 95 % CI 34.6-55.6, p < 0.001) and were more likely to die when the test was done at 45 degrees (OR 3.3, 95 % CI 1.7-6.3, p = 0.001), 60 degrees (OR 3.1, 95 % CI 1.7-5.9, p < 0.001) and 90 degrees (OR 6.0, 95 % CI 1.9-18.5, p = 0.002) as compared to 0 degrees.Conclusion: The angle at which the test is performed significantly affects the amount of time mosquitoes spend resting on the nets, and subsequently mortality. Angle must thus be considered as an important component in the performance of the assay and duly incorporated into the guidelines.