Epidemiological and cluster characteristics of dengue fever in Yunnan Province, Southwestern China, 2013-2023.

Background: Yunnan Province, located in the southwestern part of China and neighboring endemic dengue regions of Southeast Asia, has experienced annual autochthonous outbreaks of dengue fever from 2013 to 2023. This study examines the epidemiological and spatiotemporal clustering characteristics of dengue within the province.

Methods: Descriptive epidemiological methods were used to analyse outbreak characteristics. Excel 2019 and ArcGIS 10.3 software were used to establish a case database and for mapping. Spatial autocorrelation and spatio-temporal clustering analysis were employed to study the features of spatial clustering.

Results: From 2013 to 2023, 30,666 dengue cases were reported in Yunnan Province, of which 22,806 (74.37%) were indigenous and 7,860 (25.63%) were imported. Imported cases from Myanmar, Laos, and Vietnam were reported each year, with indigenous outbreaks occurring from June to December. The majority of cases occurred among young adults, mainly farmers, service workers, homemakers, and the unemployed. There was a significant temporal and spatial clustering of dengue incidence, with intense local clustering in the southwestern border areas of the province from July to November, particularly in Xishuangbanna, Dehong, Lincang, Pu'er, and Honghe prefectures.

Conclusion: Autochthonous outbreaks of dengue fever in Yunnan Province occurred predominantly in the border areas adjacent to Myanmar, Laos, and Vietnam. The largest outbreak in the province's history occurred in 2023, related to the increase in imported cases following the reopening of borders after the COVID-19 pandemic. Dengue fever is considered primarily an imported disease in Yunnan, emphasizing the need for enhanced control of cross-border transmission and mosquito vector management.