Comparative epidemiological characterization of two local outbreaks of dengue fever in Nanshan District,Shenzhen,2023

WANG Ying; WANG Zhengduo; WANG Jia; HUANG Yanfei; XU Yanzi

doi:10.19821/j.1671-2781.2025.02.017

Abstract：Objective To analyze and compare the epidemiological characteristics of two local outbreaks of dengue fever in Nanshan District,Shenzhen in 2023,so as to provide a reference for prevention and control strategies for dengue fever outbreaks in the future.Methods Descriptive epidemiological analyses were used to analyze the time of onset,population characteristics,and characteristics of healthcare-seeking behaviors of the two outbreaks,and mosquito vector densities were assessed using the Brett index(BI).Results The two outbreaks were an orchard outbreak and a construction site outbreak,with 38 and 91 reported cases,respectively;the onset of disease occurred between August and November,and both lasted 3 months;the male-to-female sex ratios of the cases were 2.2∶1 and 7.3∶1,respectively;the median ages of the cases were 41 and 42 years old,respectively;and the main occupations were farmers and migrant workers,respectively.Before reporting of the indicated case,66.70%(2/3)of the cases in the orchard outbreak chose to seek medical treatment at the community health center,while 50.00%(6/12)of the cases in the construction site outbreak chose not to seek medical treatment,and the correct rate of the first diagnosis was 0.After reporting of the indicated case,both the orchard outbreak and the construction site outbreak preferred the second-level and above general hospitals,and the correct rate of the first diagnosis was 61.70%and 54.80%,respectively.The co-exposed persons screening positive rate of the construction site outbreak was higher(25.25%)than that of the orchard outbreak(2.20%),and the latent infection rate was 18.18%.The Breteau index for the first monitoring of the orchard outbreak was 43,which was higher than the result of the construction site outbreak,which was 18.Conclusion The high density of mosquito vectors in the orchard outbreak and the high rate of latent infection and co-exposed persons'positive screening rate in the construction site outbreak were the main reasons for the long duration of the two outbreaks.It is necessary to pay attention to the control efforts in the early stage of the epidemic,and to strengthen the health monitoring of personnel at construction sites and other workplaces with frequent personnel changes in order to contain the spread of the epidemic in a timely manner.