Abstract:

Objective To analyze the epidemiological characteristics of dengue fever in Hunan Province for scientific basis in prevention and control of this infection. Methods The surveillance data of dengue fever cases in Hunan Province were collected through the China Disease Prevention and Control Information System from 2017 to 2022. Descriptive epidemiology was used to analyze the time, population, and geographical distribution characteristics of dengue fever epidemic in Hunan Province, and the differences between imported and local cases were analyzed and compared as well. Results Accumulative 943 cases of dengue infection were reported in Hunan Province from 2017 to 2022. Of the reported cases, 514 were imported (54.51%), 429 were local infections (45.49%), and 1 death occurred. The peak incidence was in August to November (n=746, 79.11%), and the infection was spread in 108 counties (cities, districts) under the 14 cities (prefectures). The male-to-female ratio of imported cases was 2.70:1, which was higher than the local case ratio of 1.01:1. The median age of the imported cases was 39 (30, 50) years, and the imported infection was most seen in patients aged 20 to 49 years (n=341, 66.34%). The farmers, personnel in commercial services and workers were most affected (n=365, 71.01%). The median age of local cases was 46 (33, 55) years, and the infection was most seen in patients aged 30-69 years (n=309, 72.03%). The occupations were associated with farmers, retired personnel, students, housework and the unemployed (n=307, 71.56%). The median time from onset to diagnosis for imported cases was 5 (2, 7) days, which was longer than the 4 (2, 6) days for local infections. The difference was significant (Z=-8.776, P<0.05). The imported cases were chiefly from southeast Asian countries such as Cambodia, Myanmar and Thailand, while the domestic infection was from Guangdong, Yunnan and Guangxi provinces. Conclusion The dengue fever epidemic in Hunan Province is obviously characterized by importation and seasonality. The findings suggest that disease control institutions at all levels should conduct timely risk assessments of the transmission and take effective measures to reduce mosquito vector density during the epidemic season so as to prevent epidemics and outbreaks.

Key words: Dengue fever, Epidemiological characteristics, Imported case, Local case, Hunan Province