Explosive Chikungunya Virus Outbreak in China.

Background: Chikungunya virus (CHIKV), an Aedes-borne alphavirus, is a growing global health concern. Until now, China had experienced only sporadic outbreaks linked to imported cases.

Methods: We analyzed epidemiological, clinical, and public health data from the ongoing 2025 Guangdong outbreak, the largest chikungunya epidemic recorded in China.

Results: The outbreak began in Foshan on July 8, 2025, with over 3,000 confirmed cases in the first two weeks and more than 10,000 by late August. Clinical presentations were typical of chikungunya fever, including acute fever, arthralgia, and rash, with no severe complications or deaths. Local and interregional spread included travel-associated cases in Macao, Hong Kong, Taiwan, and Guangxi. Authorities implemented expanded PCR testing, isolation of cases in mosquito-proof facilities, and comprehensive vector control. Clinical management remains supportive, with no licensed antivirals.

Conclusion: The unprecedented scale and rapid spread of CHIKV in Guangdong underscore the role of ecological and mobility factors in transforming local introductions into large epidemics. Strengthened surveillance, genomic analysis, regional data sharing, and vaccine preparedness will be critical to curb future arbovirus threats in China.