Epidemiological characteristics of imported dengue fever cases in Beijing, 2014–2023

Objective  To analyze the epidemiological characteristics of imported dengue fever cases in Beijing from 2014 to 2023, and provide evidence for the prevention and control of the disease.

Methods The incidence data of imported dengue fever in Beijing during this period were collected from China Information System for Disease Control and Prevention and epidemiological investigation of reported cases. Seasonal patterns of the incidence were analyzed by using the concentration index and circular distribution method. Rose diagrams, circular distribution plots, and Sankey diagrams were generated by using R 4.4.2.

Results A total of 240 confirmed dengue fever cases were reported in Beijing during 2014—2023, all were imported from other countries or other provinces in China. Demographic analysis showed that 143 cases were men and 97 cases were women (1.47∶1), and the highest incidence was observed in age group 31～<40 years (35.83%). Most cases were office workers (32.50%). In terms of time distribution, the incidence showed obvious seasonality with 78.8% of the cases occurring between May and November and incidence peak during June 8th - November 28th. The high counts of the cases were reported in Chaoyang, Haidian, and Fengtai districts. In the imported dengue fever cases from other countries, 69.80% were from Southeast Asia, and in the imported dengue fever cases from other provinces in China, 70.59% were from Yunnan. The median (P₂₅, P₇₅) time from onset to medical care seeking was 6 (4, 9) days, The cases were mainly reported by specialized infectious disease hospitals, grade III general hospitals, and foreign-funded/international hospitals.

Conclusion All the dengue fever cases in Beijing were imported, showing distinct seasonal patterns closely associated with the density of Aedes albopictus. Strengthened early detection of imported cases and case management are essential to low local transmission risk.