In 2024, two novel lineages of dengue virus serotype 2 (DENV-2) were identified in Xishuangbanna, Yunnan Province, China. These lineages belong to the cosmopolitan_asian-pacific subtype and likely originated from Thailand and Cambodia, respectively, highlighting increased genetic diversity and complex transmission dynamics in the region.
Background
Dengue fever is a widespread mosquito-borne viral infection endemic to tropical and subtropical regions, including Southeast Asia and parts of China. Yunnan Province, bordering dengue-endemic countries such as Myanmar, Laos, and Vietnam, has experienced recurrent outbreaks since 2013, particularly in the Xishuangbanna region. The region's climate and geography favor Aedes mosquito proliferation, facilitating dengue transmission. Understanding the genetic diversity and transmission sources of dengue virus is critical for effective disease control and prevention.
Data Highlights
Parameter
Value
Total suspected dengue cases tested
321
DENV-positive cases detected
101
DENV-2 cases identified
85
DENV-1 cases identified
1
DENV-2 E1 sequences obtained
81
Complete DENV genomes sequenced
12
Distinct DENV-2 lineages identified
2
Key Findings
Among 101 dengue-positive patients, 85 were infected with DENV-2 and 1 with DENV-1.
DENV-2 strains belonged predominantly to the cosmopolitan genotype, specifically the cosmopolitan_asian-pacific subtype.
Two novel distinct lineages within the cosmopolitan_asian-pacific subtype were identified in Yunnan.
Phylogenetic and molecular clock analyses suggest lineage-1 originated from Thailand, while lineage-2 likely originated from Cambodia.
Analysis of GenBank sequences revealed increased genetic diversity and complexity of DENV-2 genotypes circulating in Xishuangbanna.
The findings indicate ongoing introduction and local evolution of DENV-2 in Yunnan, driven by cross-border transmission.
Clinical Implications
The identification of two novel DENV-2 lineages underscores the need for continuous molecular surveillance to monitor viral evolution and transmission pathways in border regions. Enhanced understanding of dengue virus genetic diversity can inform targeted vector control and outbreak response strategies. Clinicians should remain vigilant for dengue infections given the region's high transmission risk and the potential for introduction of diverse viral strains.
Conclusion
This study reveals the emergence of two new lineages of cosmopolitan DENV-2 in Yunnan Province, originating from neighboring Southeast Asian countries. These findings emphasize the importance of regional cooperation and genomic monitoring to effectively control dengue outbreaks in border areas.
References
Identification of Two Novel Lineages of Dengue Virus Serotype 2 in Yunnan, China, 2024
The agency outlined early regulatory actions supporting nonanimal methods, including draft guidance, artificial intelligence tools, and expanded use of human-relevant data models.
