The analysis of clinical and laboratory data: a large outbreak of dengue fever in Chaozhou, Guangdong province, China

Unraveling the Genomic Evolution of Dengue Virus Serotype 1: A Case Study from Yantai, China

In August 2023, we identified a case of dengue fever in Yantai City, which was imported from Xishuangbanna, China. To investigate its evolutionary history and population dynamics, we utilized the metatranscriptomic method to obtain the virus' whole genome sequence. Together with 367 selected dengue virus whole genome sequences from the NCBI database, we constructed a time-scaled Maximum Clade Credibility (MCC) tree. We found that our sequence exhibited a high homology with a sequence of DENV1 (OR418422.1) uploaded by the Guangzhou Center for Disease Control and Prevention in 2023, with an estimated divergence time around 2019 (95% HPD: 2017-2023), coinciding with the emergence of SARS-CoV-2. The DENV strain obtained in this study belongs to genotype I of DENV1. Its ancestors experienced a global epidemic around 2005 (95% HPD: 2002-2010), and its progeny strains have spread extensively in Southeast Asia and China since around 2007 (95% HPD: 2006-2011). The Bayesian skyline plot indicates that the current population of DENV1 has not been affected by SARS-CoV-2 and is expected to maintain stable transmission. Hence, it is imperative to track and monitor its epidemiological trends and genomic variations to prevent potential large-scale outbreaks in the post-SARS-CoV-2 era.

Dengue fever and dengue virus in the People's Republic of China

Infection with dengue virus (DENV) leads to symptoms variable from dengue fever to severe dengue, which has posed a huge socioeconomic and disease burden to the world population, particularly in tropical and subtropical regions. To date, four serotypes of DENV (DENV-1 to DENV-4) have been identified to sustain the transmission cycle in humans. In the past decades, dengue incidences have become more frequent, and four serotypes and various genotypes have been identified in PR China. Several large-scale dengue outbreaks and frequent local endemics occurred in the southern and coastal provinces, and the imported dengue cases accounted primarily for the initiation of the epidemics. No antiviral drug exists for dengue, and no vaccine has been approved to use in PR China, however strategies including public awareness, national reporting system of infectious diseases and public health emergencies, vector mosquito control, personal protection, and improved environmental sanitation have greatly reduced dengue prevalence. Some new technologies in vector mosquito control are emerging and being applied for dengue control. China's territory spans tropical, subtropical, and temperate climates, hence understanding the dengue status in China will be of beneficial for the global prevention and control of dengue. Here, we review the dengue status in PR China for the past decades and the strategies emerging for dengue control.

Increase in cases of dengue in China, 2004-2016: A retrospective observational study

BACKGROUND

Dengue fever (DF) is a vector-bore infectious disease that can infect humans, and has been recognized as a global public health threat, with significant morbidity and mortality rates.

METHOD

To describe the epidemiological profile of DF in China during 2004-2016, the morbidity data of DF by age-group, season (different months) and geographic location (different provinces) were obtained from the public health science data center of China for subsequent epidemiological analysis.

RESULTS

The results showed that the incidence of DF shows striking annual variations, and two large outbreaks occurred in 2006-2007 and during 2012-2015. The results of the average morbidity rates (cases/100,000 population) for human DF indicated that among all dengue fever cases, Guangdong in southern area of China had the highest rates (3.8160 cases/100,000 population), followed by Yunnan (0.6614 cases/100,000 population), Fujian (0.3463 cases/100,000 population) and Guangxi (0.1474 cases/100,000 population). Epidemic peaks occurred in late June and early November, and the incidence rate among middle-aged people (30-45 years old) was relatively high, followed by rates among 15-29 and 45-59 age groups.

CONCLUSION

In this study, we demonstrated the epidemiological profile of DF circulating in China and revealed the geographic distribution, dynamic transmission, seasonal asymmetries and age distribution, which will provide guidelines on the prevention and control of DF in China. The present investigation is useful in the risk assessment of DF transmission, to predict DF outbreaks and the prevention and control strategies should be used along with surveillance to reduce the spread of DF in China.