Ecological surveillance analysis of dengue vector Aedes in Chongqing, 2020.

Objective To analyze the Aedes surveillance data of Chongqing in 2020, and we provide a basis for control of Aedes-borne diseases in Chongqing. Methods Wanzhou, Yubei and Shapingba districts with local dengue outbreaks, and Qianjiang, Dazu districts and Dianjiang county with no local dengue cases in Chongqing in 2019 were selected as investigation points. The larvae of Aedes mosquito were monitored by Breteau index method and mosquito ovitrap index method, adult Aedes mosquito was monitored by double net trap method. The surveillance data of larval and adult Aedes mosquitoes from six surveillance sites of Chongqing were analyzed using Excel 2010 software for a preliminary assessment of the risk of dengue transmission. Results In Apr.-Dec. 2020, the mean Breteau index (BI) of Aedes mosquitoes was 4.50. The BI of Chongqing from June to September were all >5, indicating a risk of dengue transmission; the BI of Shapingba in June, that of Yubei from June to July, and that of Wanzhou from July to August were >10, indicating a risk of dengue outbreak; the mean mosquito ovitrap index (MOI) was 2.15, the MOI of Yubei from July to August was >10, indicating a risk of dengue outbreak. The mean adult density of Aedes was 0.86 mosquitoes per net per hour. The net trap index of Aedes density in Shapingba district and Dianjiang county was 1.81 /(net⋅h) and 1.48 /(net⋅h), respectively, followed by Wanzhou district 1.04 /(net⋅h). The adult density of Aedes in Shapingba from June to September, that of Wanzhou from June to July, that of Dianjiang from May to June and August to September were higher than 2 mosquitoes per net per hour. Conclusion In 2020, the dengue transmission risk varies in different months in the six districts in Chongqing. Yubei, Shapingba and Wanzhou have higher risk than other investigative points. It is suggested that Aedes surveillance and risk assessment should be strengthened in key districts to ensure sustainable control of Aedes for the prevention and control of Aedes-borne diseases in Chongqing. [ABSTRACT FROM AUTHOR]