Epidemiology and spillover risk of SFTSV in animals across East Asia

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging tick‑borne zoonosis in East Asia, yet the contribution of animals to virus maintenance and spillover remains incompletely characterized. This review synthesizes current evidence of SFTS virus (SFTSV) infection across domestic livestock, companion animals, wildlife, and captive species, focusing on host range, geographic distribution, diagnostics, and reports of viral RNA and virus isolation. Available data indicate that SFTSV exposure and infection occur across a broad range of animal hosts, supporting a multi-host ecological framework rather than a simple single-reservoir interpretation. Domestic ruminants frequently exhibit high seroprevalence and may function as sentinels of enzootic activity, while occasional virus isolation from cattle demonstrates that viable virus can be recovered from naturally infected livestock, although this does not establish reservoir or amplification competence. Companion animals are considered a potential interface for interspecies transmission, as some studies have documented severe clinical disease, high viral loads, and cat-associated human transmission events supported by varying levels of epidemiological and genomic evidence. Studies in wildlife further document exposure and natural infection across diverse taxa, although their specific roles in viral maintenance remain unresolved. Interpretation of these findings depends heavily on the diagnostic modality: serology primarily indicates prior exposure, RNA detection supports current or recent infection, and virus isolation demonstrates that viable virus was present in the sampled material. Integrating animal infection data within an ecological framework reveals major knowledge gaps related to reservoir competence, infectious shedding, phylogenetic connections among animal, tick, and human cases, and implications for prevention. The review underscores the need for One Health surveillance that incorporates clinical data from companion animals and applies evidence‑based interpretation to improve recognition of animal–human interfaces associated with potential spillover risk.