Abstract:

Objective To analyze the epidemiological characteristics and temporal trend of dengue fever in Chengdu area for scientific evidences to effectively control epidemic import and local transmission. Methods The case data of dengue fever reported in Chengdu area from 2011 to 2023 were collected from the Chinese Disease Prevention and Control Information System as well as epidemiological investigation. Descriptive epidemiology was used to analyze the epidemiological characteristics, and Joinpoint regression model was used to analyze time trends. Results In total, 269 cases of dengue were reported in Chengdu area from 2011 to 2023, including 1 indigenous case, 197 imported cases from overseas, and 71 imported cases from other provinces within China. The top three districts/counties with the higher number of imported cases were Xindu District (28 cases), Jinniu District (27 cases), and Qingyang District (24 cases). Of the imported cases, the onset age was dominant in 21-50 years (225 cases, 83.96%). One hundred and fifty were males, and 118 females, with a sex ration of 1.27∶1. The occupational distribution was led by commerce/services (60 cases, 22.39%), homemakers/unemployed (59 cases, 22.01%), and workers (47 cases, 17.54%). Overseas imported cases originated primarily from Southeast Asia (169 cases, 85.79%), and domestic imported cases came from Yunnan Province (69 cases, 97.18%) and Guangdong Province (2 cases, 2.82%). Overseas imported cases occurred year-round, and the incidence peaked from June to October (69.54%, 137/197). Domestic imported cases were reported exclusively between August and November. The locally acquired case occurred in October. Overall, the incidence of dengue fever in Chengdu area exhibited a “slow rise-rise-decline-rise” trend from 2011 to 2023 (AAPC=39.26%, P<0.05). The case number was slowly increased from 2011 to 2018 (APC=28.53%, P<0.05), shot rapidly from 2018 to 2019 (APC=322.90%, P<0.05), sharply decreased from 2019 to 2021 (APC=-99.58%, P<0.05), and greatly went up from 2021 to 2023 (APC=2 746.79%, P<0.05). Conclusion The dengue fever epidemic in Chengdu area is primarily influenced by imported cases from Southeast Asian regions and neighboring domestic provinces. Summer and autumn seasons represent critical periods for prevention and control dengue fever in Chengdu area. Effective measures should be implemented to address the risk of epidemic spread caused by imported cases and potential local outbreaks.

Key words: Dengue fever, Epidemiological characteristics, Joinpoint regression model, Chengdu City