Objective To investigate the results of emergency surveillance of Aedes vector before mosquito control after the occurrence of the index case of dengue fever in the epidemic areas of Chongqing, China, and to provide a basis for future surveillance of Aedes vector and early warning research on the risk of local transmission of dengue fever. Methods The surveillance data of Aedes vector were collected after the first cases of dengue fever were reported and before the mosquito control measures were adopted in each epidemic area of Chongqing, including Breteau index (BI) and double mosquito net index (DMNI), and SPSS 25.0 software was used for data description and linear regression analysis. Results The average BI for the first-time emergency surveillance in all epidemic areas was 11.01, and the average was 5.10 mosquitoes/net·hour, with a positive correlation between the two indices ( r=0.517, P<0.05). The bivariate linear regression analysis was used to establish the regression equation of BI and DMNI: y (BI)=7.07+0.82 x ( F=61.232, P<0.005), and the early warning of dengue fever risk in Chongqing was stratified into four levels based on this equation. Conclusion Graded assessment of BI and DMNI acts as an indicator for the early warning of dengue fever risk. For Chongqing, BI controlled below 7 and DMNI controlled below 3 mosquitoes/net·hour may reduce the risk of local outbreak of dengue fever.

Objective To investigate the density fluctuation of the dengue vector Aedes albopictus and its resistance to commonly used insecticides in four regions of Zhejiang province, China, and to provide a basis for rational selection and use of insecticides and scientific prevention and control of dengue. Methods The density of adult Ae. albopictus was monitored by the double mosquito net method in four cities of Hangzhou, Ningbo, Quzhou, and Yiwu in Zhejiang province from April to November of 2018. The larvae were collected and reared to adults for determining resistance using the diagnostic doses of insecticides. Results The annual average net trap index was 1.33 mosquitoes/net·hour in the four prefectures of Zhejiang province, and that was 1.60 mosquitoes/net·hour in residential areas, which was the highest among three habitats. The Ae. albopictus population of Hangzhou was sensitive to three pyrethroids and malathion, and showed suspected resistance to propoxur. The mosquito population of Ningbo showed sensitive to beta-cypermethrin, suspected resistance to deltamethrin, permethrin, and propoxur, and resistance to malathion. The Ae. albopictus populations of Quzhou and Yiwu were sensitive to malathion, and exhibited suspected resistance to three pyrethroids and propoxur. Of the mosquito populations of the four cities, 5.00%, 60.00%, and 35.00% showed resistance, suspected resistance, and sensitivity to five insecticides, respectively. Conclusion In the four cities of Zhejiang province, the density of Ae. albopictus in residential areas and parks peaks in July. The mosquitoes develop varying degrees of resistance to the tested insecticides. Strengthening the surveillance of their density fluctuation and insecticide resistance contributes to slowing the development of resistance and effectively controlling dengue.

Objective To evaluate the dengue prevention and control effectiveness of government-purchased vector control services and to perfect the pattern of government-purchased pest control services in the emergency management of dengue. Methods We systematically collected the data about dengue cases, the assessment of epidemic foci, and the management and evaluation from the municipal mosquito vector control team for emergency response in Guangzhou, Guangdong province, China, 2019. We assessed the effectiveness of the team's performance by epidemic duration and cumulative case number at the epidemic focus. The rank sum test was used to analyze whether the epidemic situation was affected by the response, also different response, from the team. Results In 2019, a total of 1 478 local cases were reported in Guangzhou, distributed in 680 epidemic foci, including 143 (21.03%) foci of outbreaks. The team dealt with 28 epidemic foci, accounting for 4.12% of the total foci. The density of adult mosquitoes was significantly reduced after mosquito vector control from the team ( t=6.909, P<0.001). Both the epidemic duration and case number were significantly lower in the foci where the treatment began within eight days after the epidemic emerged and there were at least two round actions than in the foci without the treatment ( Z=3.984, 2.345, 2.048, and 3.586, all P<0.05). Conclusion Early and full-scale control of mosquitoes at dengue epidemic foci by the municipal mosquito vector control team for emergency response, in the form of government-purchased services, can contain the community spread of dengue. In future dengue prevention and control by mosquito vector control, more personnel should be added, and other control forces should be united to establish an effective mechanism of surveillance, evaluation, and emergency response.

Objective To investigate the application effect of gridding management in the prevention and control of dengue fever in Jinghong, Yunnan province, China, and to provide a scientific basis for developing effective prevention and control strategies for dengue fever. Methods Based on the gridding management system of dengue fever prevention and control in Jinghong in 2019, epidemiological description and the geographic information system were used to analyze and evaluate the effectiveness of gridding management in the prevention and control of dengue fever in Jinghong in 2019. Results In 2019, 28 dengue fever grid points were divided in the urban area of Jinghong city. Imported cases occurred in June, the outbreak of dengue fever was observed in July, and the cases of dengue fever reached the peak in September (1 775 cases). For the 28 grid points in Jinghong from June to November, the monthly mean Breteau index (BI) was 11.18, 18.42, 14.62, 14.02, 5.81, and 2.09, respectively, the rate of reaching the standard of BI was 52.56%, 44.76%, 51.66%, 46.57%, 74.01%, and 91.71%, respectively, and the number of dengue cases were 8, 47, 540, 1 775, 473, and 72, respectively. Conclusion Gridding management can effectively prevent and control dengue fever by improving the rate of reaching the standard of BI in the urban area of Jinghong. It is suggested that the local government should further develop the grid management of dengue fever.

Objective To investigate the current status of residents' awareness of dengue in Jinghong, Xishuangbanna Dai autonomous prefecture (Xishuangbanna prefecture), Yunnan province, China, and to provide a scientific basis for the establishment of accurate response mechanism and the sustainable control of dengue. Methods A representative grid was selected randomly from the grids with dengue prevention and control during the period of dengue outbreak in Jinghong in 2019. A questionnaire survey was conducted among the residents in the grid in a one-to-one question- and-answer manner. SPSS 20.0 statistical software was adopted for the statistical analysis. Results A total of 249 valid questionnaires were collected. The chi-square analysis revealed that urban residents paid more attention to dengue-related knowledge than rural residents ( χ ²=12.444, P=0.040). The education system staff and the highly educated ones paid more attention to the knowledge of mosquito control. Residents with different occupations, monthly average income levels, and levels of education chose different ways of seeking medical treatment if they were inadvertently infected with dengue. The highly educated ones, those high-income earners, and the education system staff were more inclined to go to the grade A tertiary hospitals. Urban residents held the view that there were more dengue infections around themselves than around rural residents. The highly educated population had a higher proportion of people who thought they had enough knowledge of dengue prevention and control than the less educated population. The results of unconditional logistic regression analysis demonstrated that residents with different ages, levels of education, and current places of residence showed different abilities to use new media to acquire knowledge about dengue prevention and control. Conclusion In Jinghong, Xishuangbanna prefecture, the elderly, the rural residents, the less educated people, and the low-income earners had a relatively low level of awareness of dengue. It is suggested that in future, the above-mentioned populations should be focused on in the establishment of local accurate response mechanism and the scientific prevention and control of dengue.