Seroprevalence of segmented flavi-like Alongshan virus in horses.

The emergence of new pathogens poses a significant threat to global health, exacerbated by climate change, biodiversity loss, and increased globalization. Ticks, as vectors for various pathogens, contribute to the rising incidence of diseases. Surveillance programs are crucial for identifying and controlling emerging pathogens. This study focuses on the Alongshan virus (ALSV), a segmented flavi-like virus first identified in humans in China in 2017. Despite its ability to infect a wide range of mammals, the natural hosts and transmission pathways of ALSV remain poorly understood. Therefore, we investigated the prevalence of ALSV in equine cohorts from different geographical regions to assess its spread and potential risk. Using commercial serum pools from the Americas, Europe, and Oceania, we detected anti-ALSV antibodies in 12 out of 13 pools, indicating a broader geographical distribution of ALSV than previously known. In a cohort of 473 Thoroughbred horses from Germany, 87.1 % tested positive for ALSV antibodies, with a significant correlation between antibody positivity and age. Longitudinal tracking of 124 horses over five years revealed dynamic changes in antibody levels, with 71.77 % testing positive at some point during the study. Our findings demonstrate a high prevalence of ALSV antibodies in equine populations across diverse regions, suggesting frequent exposure to the virus. The study highlights the importance of horses as sentinel models for monitoring tick-borne pathogens and underscores the need for further research to understand the potential risk of ALSV exposure to human and animal health.