Seroprevalence and risk factors associated with bluetongue and Schmallenberg virus infections in domestic small ruminants in Türkiye.

Bluetongue virus (BTV) and Schmallenberg virus (SBV) are Culicoides-borne viruses that cause major reproductive and economic losses in ruminants, with their spread shaped by climate-driven vector activity and growing livestock movements. This cross-sectional study assessed the seroprevalence and risk factors for both viruses in small ruminants in eastern Türkiye. A total of 596 sheep and goats from 65 farms across 11 districts were sampled between October 2024 and June 2025 and tested using commercial competitive enzyme-linked immunosorbent assays (c-ELISA). Statistical analyses were performed using SPSS, and chi-square tests were applied to assess associations between BTV and SBV seroprevalence and various potential risk factors. Overall, 69.8% (95% CI: 65.94%–73.46%) of the animals were seropositive for BTV, with similar rates in sheep and goats. District-level variation showed a trend toward statistical significance (P = 0.053), indicating possible spatial heterogeneity in BTV exposure. Contact with cattle was the only significant predictor of BTV seropositivity (aOR = 2.35), highlights the importance of cattle in the local transmission cycle. No associations were observed between species or sex. SBV antibodies were detected in only two animals (0.33%), precluding meaningful statistical analysis. These findings confirm that BTV remains endemic in eastern Türkiye and highlight the need for integrated multispecies surveillance, whereas the very low SBV seroprevalence underscores the importance of periodic monitoring under shifting environmental conditions.