Analysis of imported Chikungunya cases in China from 2006 to 2026.

BACKGROUND

Chikungunya fever (CHIKF) has impacted 119 countries and regions globally. In 2025, a local outbreak occurred in Guangdong, China, driven by imported cases from Sri Lanka, resulting in over 25,000 diagnoses. This highlights CHIKF as a significant public health concern. Analyzing imported cases in China and discussing travel medicine and related preventive measures is essential.

METHODS

This study reviewed literature and reports on CHIKF published in international and Chinese databases, as well as government reports, from 2006 to March 1, 2026. Data related to CHIKF, including case numbers, virus types, source countries, and high-risk provinces, were collected, synthesized, and summarized using descriptive statistical methods. Phylogenetic tree analysis, temporal signal assessment, and mutation analysis were conducted on the Chikungunya virus (CHIKV) sequences sourced from China.

RESULTS

Between 2006 and 2026, China reported a total of 259 imported CHIKF cases, including those from Hong Kong, Macao, and Taiwan. These imported cases contributed to over 25,000 local transmission cases. Among confirmed cases, the East/Central/South African (ECSA) strain was the most prevalent (61.7%), followed by the Asian strain (37.4%). The primary countries of acquisition were Indonesia and Myanmar, with the Asian strain mostly detected in travelers returning from Indonesia, while the ECSA strain was found in travelers from South and Southeast Asia. The rate of evolution for Chinese cases mirrors that of global trends, and no new branches have emerged. The newly identified mutations in recent years exhibit high-frequency variations in the sequences, along with potential unidentified mutations that have appeared.

CONCLUSION

Returnees from countries with high incidence rates of CHIKF significantly increase the risk of reintroducing the disease to China. An increased number of mutations may enhance the transmission of CHIKV. Therefore, it is crucial to enhance the dissemination of relevant prevention and control measures and expedite vaccine approval to mitigate the incidence of CHIKF among travelers and reduce viral transmission.