The epidemiology and evolutionary dynamics of massive dengue outbreak in China, 2019

Shaowei Sang; Yujuan Yue; Yiguan Wang; Xiangwei Zhang

doi:10.3389/fmicb.2023.1156176

The epidemiology and evolutionary dynamics of massive dengue outbreak in China, 2019

Front Microbiol. 2023 Apr 17:14:1156176. doi: 10.3389/fmicb.2023.1156176. eCollection 2023.

Authors

Shaowei Sang^{1

2}, Yujuan Yue³, Yiguan Wang⁴, Xiangwei Zhang⁵

Affiliations

¹ Clinical Epidemiology Unit, Qilu Hospital of Shandong University, Jinan, Shandong, China.
² Clinical Research Center of Shandong University, Jinan, Shandong, China.
³ State Key Laboratory of Infectious Disease Prevention and Control, Chinese Center for Disease Control and Prevention, National Institute for Communicable, Disease Control and Prevention, Beijing, China.
⁴ Institute of Ecology and Evolution, University of Edinburgh, Edinburgh, United Kingdom.
⁵ Department of Thoracic Surgery, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China.

Abstract

Introduction: In 2019, China experienced massive dengue outbreaks with high incidence and expanded outbreak areas. The study aims to depict dengue's epidemiology and evolutionary dynamics in China and explore the possible origin of these outbreaks.

Methods: Records of confirmed dengue cases in 2019 were obtained from the China Notifiable Disease Surveillance System. The sequences of complete envelope gene detected from the outbreak provinces in China in 2019 were retrieved from GenBank. Maximum Likelihood trees were constructed to genotype the viruses. The median-joining network was used to visualize fine-scale genetic relationships. Four methods were used to estimate the selective pressure.

Results: A total of 22,688 dengue cases were reported, 71.4% of which were indigenous cases and 28.6% were imported cases (including from abroad and from other domestic provinces). The abroad cases were predominantly imported from Southeast Asia countries (94.6%), with Cambodia (3,234 cases, 58.9%), and Myanmar (1,097 cases, 20.0%) ranked as the top two. A total of 11 provinces with dengue outbreaks were identified in the central-south of China, of which Yunnan and Guangdong provinces had the highest number of imported and indigenous cases. The primary source of imported cases in Yunnan was from Myanmar, while in the other ten provinces, the majority of imported cases were from Cambodia. Guangdong, Yunnan and Guangxi provinces were China's primary sources of domestically imported cases. Phylogenetic analysis of the viruses in outbreak provinces revealed three genotypes: (I, IV, and V) in DENV 1, Cosmopolitan and Asian I genotypes in DENV 2, and two genotypes (I and III) in DENV 3. Some genotypes concurrently circulated in different outbreak provinces. Most of the viruses were clustered with those from Southeast Asia. Haplotype network analysis showed that Southeast Asia, possibly Cambodia and Thailand, was the respective origin of the viruses in clade 1 and 4 for DENV 1. Positive selection was detected at codon 386 in clade 1.

Conclusion: Dengue importation from abroad, especially from Southeast Asia, resulted in the dengue epidemic in China in 2019. Domestic transmission between provinces and positive selection on virus evolution may contribute to the massive dengue outbreaks.

Keywords: China; dengue; epidemiology; evolution; imported.

Grants and funding

This work was supported by the National Natural Science Foundation of China (NSFC) (Grant Number 81602898) and the Shandong Natural Science Foundation (ZR2021MH242). The funders had no role in the study design, data collection and analysis, decision to publish or preparation of the manuscript.