Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Socinstrasse 57, P.O. Box, 4002, Basel, Switzerland.
University of Basel, Petersplatz 1, P.O. Box, 4001, Basel, Switzerland.
Parasit Vectors. 2019 Nov 21;12(1):554. doi: 10.1186/s13071-019-3798-8.
The threat of mosquito-borne diseases is increasing in continental Europe as demonstrated by several autochthonous chikungunya, dengue and West Nile virus outbreaks. In Switzerland, despite the presence of competent vectors, routine surveillance of arboviruses in mosquitoes is not being carried out, mainly due to the high costs associated with the need of a constant cold chain and laborious processing of thousands of mosquitoes. An alternative approach is using honey-baited nucleic acid preserving cards (FTA cards) to collect mosquito saliva that may be analysed for arboviruses. Here, we evaluate whether FTA cards could be used to detect potentially emerging viruses in an area of low virus prevalence in combination with an effective mosquito trap.
In a field trial in southern Switzerland we measured side-by-side the efficacy of the BG-Sentinel 2, the BG-GAT and the Box gravid trap to catch Aedes and Culex mosquitoes in combination with honey-baited FTA cards during 80 trapping sessions of 48 hours. We then screened both the mosquitoes and the FTA cards for the presence of arboviruses using reverse-transcription PCR. The efficacy of the compared trap types was evaluated using generalized linear mixed models.
The Box gravid trap collected over 11 times more mosquitoes than the BG-GAT and BG-Sentinel 2 trap. On average 75.9% of the specimens fed on the honey-bait with no significant difference in feeding rates between the three trap types. From the total of 1401 collected mosquitoes, we screened 507 Aedes and 500 Culex females for the presence of arboviruses. A pool of six Cx. pipiens/Cx. torrentium mosquitoes and also the FTA card from the same Box gravid trap were positive for Usutu virus. Remarkably, only two of the six Culex mosquitoes fed on the honey-bait, emphasising the high sensitivity of the method. In addition, two Ae. albopictus collections but no FTA cards were positive for mosquito-only flaviviruses.
Based on our results we conclude that honey-baited FTA cards, in combination with the Box gravid trap, are an effective method for arbovirus surveillance in areas of low prevalence, particularly where resources are limited for preservation and screening of individual mosquitoes.
随着几起基孔肯雅热、登革热和西尼罗河病毒的本地暴发，蚊虫传播疾病的威胁在欧洲大陆不断增加。在瑞士，尽管存在有媒介能力的蚊虫，但由于需要持续冷链和繁琐处理数千只蚊虫，对蚊虫中虫媒病毒的常规监测尚未开展，主要是因为这方面的成本很高。另一种方法是使用带诱饵的核酸保存卡（FTA 卡）收集可能用于分析虫媒病毒的蚊虫唾液。在这里，我们评估了在病毒流行率低的地区，结合有效的蚊虫诱捕器，FTA 卡是否可用于检测潜在的新兴病毒。
在瑞士南部的一项现场试验中，我们在 80 次 48 小时的诱捕中，测量了 BG-Sentinel 2、BG-GAT 和 Box 诱捕器在结合带诱饵的 FTA 卡收集伊蚊和库蚊的效果，同时还使用反转录 PCR 对诱捕到的蚊虫和 FTA 卡进行了虫媒病毒筛查。使用广义线性混合模型评估了比较的诱捕器类型的效果。
Box 诱捕器收集的蚊虫数量是 BG-GAT 和 BG-Sentinel 2 诱捕器的 11 倍以上。平均 75.9%的标本吸食了蜂蜜诱饵，三种诱捕器的吸食率没有显著差异。在总共收集的 1401 只蚊虫中，我们筛查了 507 只伊蚊和 500 只库蚊雌性体内是否存在虫媒病毒。从一个 Box 诱捕器中采集的一组 6 只库蚊和 1 只库蚊与食蚊库蚊的混合蚊群，以及从同一 Box 诱捕器中采集的 FTA 卡，都检测到了乌苏图病毒呈阳性。值得注意的是，只有 6 只库蚊中的 2 只吸食了蜂蜜诱饵，这突出了该方法的高灵敏度。此外，有两批采集的白纹伊蚊但没有 FTA 卡对蚊虫独有的黄病毒呈阳性。
基于我们的结果，我们得出结论，带诱饵的 FTA 卡与 Box 诱捕器相结合，是低流行地区虫媒病毒监测的有效方法，特别是在资源有限的情况下，无法用于个体蚊虫的保存和筛查。
