Abstract:

Objective To analyze the epidemiological characteristics of imported dengue fever cases in China for scientific evidences to plan prevention and control measures for this infection. Methods Imported dengue fever cases in China from 2005 to 2023 were collected from the Information System for Disease Prevention and Control in China. Descriptive epidemiological methods were used to analyze the temporal, spatial and demographic characteristics of imported cases. Software R was used to draw the hotspot chart and Sankey map. Results From 2005 to 2023, a total of 14 376 imported dengue fever cases were reported nationwide. The overall numbers of cases showed a rapid upward trend (except for 2020-2022). The trend in the number of affected counties (cities/districts) was basically consistent with that in the number of cases. The imported cases were generally distributed in 1 454 counties (cities/districts) of 293 cities in 30 provinces (autonomous regions, municipalities directly under the central government). The provinces with a higher number of imported cases included Yunnan (5 778 cases, 40.19%), Guangdong (2 634 cases, 18.32%), Fujian (1 165 cases, 8.10%), Zhejiang (1 105 cases, 7.69%), Sichuan (469 cases, 3.26%) and Hunan (457 cases, 3.18%). The infections were mainly imported from Myanmar (5 260 cases, 36.59%), Cambodia (3 830 cases, 26.64%), Thailand (996 cases, 6.93%), Philippines (615 cases, 4.28%), Malaysia (552 cases, 3.84%), Laos (527 cases, 3.67%), Indonesia (428 cases, 2.98%) and Vietnam (416 cases, 2.89%). The imported cases pictured seasonally, and were concentrated in summer and autumn, waved between June and November nationwide. The peak period of imported cases was from August to November in Yunnan Province, and from June to October in Guangdong, Fujian, and Zhejiang provinces. The ratio of Chinese and foreign cases was 4.23∶1. The male to female ratio of the cases was 2.01∶1. The age of the victims was mainly in 21-50 years (10 967 cases, 76.29%). The main occupations of the patients were farmers/migrant workers (4 268 cases, 29.69%), commercial services staff (2 667 cases, 18.55%) and housework & unemployment (1 894 cases, 13.71%). Conclusion Imported dengue fever in China presented seasonal characteristics, mainly from Myanmar and Cambodia and imported into Yunnan and Guangdong. The infections affected more males than females, with age group and occupational aggregation characteristics. The findings suggest that dengue fever prevention and control should be carried out in key populations according to time and place.

Key words: Dengue fever, Imported cases, Epidemiological characteristics, China