Surveillance on African Horse Sickness Virus in China's Southern Border Regions

African horse sickness (AHS) is a vector-borne and noncontagious disease caused by African horse sickness virus (AHSV) that poses a severe threat to the global equine industry. As a country historically free from AHS, China faces elevated risks due to recent outbreaks in Southeast Asia in 2020 and its ecological suitability of its border regions for AHSV vectors. Therefore, we conducted consecutive molecular and serological surveillance for AHSV in high-risk border regions from 2020 to 2024. A total of 3203 equine serum samples, 2909 whole-blood samples, and 1037 collections of blood-sucking insects were collected from 103 counties across five border provinces from June to October (peak Culicoides season). Samples were analyzed using World Organization for Animal Health (WOAH)-recommended RT-qPCR (targeting VP7 gene) and blocking ELISA. Morphological identification confirmed that the collected vectors were primarily Culicoides midges, with some mosquitoes. No AHSV nucleic acid or specific antibodies were detected, which is consistent with China's AHS-free status. Combined with predictive models and regional risk factors, the likelihood of AHSV occurrence in southern China is "likely." The study highlights the urgent need for continuous surveillance and risk assessment to safeguard China's equine industry. Further regional and ecological studies on vectors and animal transportation are also essential for understanding and mitigating the risks associated with AHSV introduction.