Seroprevalence of Pestivirus Infection and Associated Risk Factors in Sheep in Konya Province, Türkiye

Pestivirus infections, including those caused by Border disease virus (BDV), are associated with reproductive disorders, neonatal losses, and persistent infections in sheep, potentially resulting in substantial economic losses. This study aimed to determine the animal- and herd-level pestivirus seroprevalence among sheep in Konya Province, Türkiye, to investigate evidence of current infection, and to identify factors associated with seropositivity. Serum and whole-blood samples were collected from 280 sheep in 16 herds. Serum samples were tested for pestivirus antibodies by competitive ELISA, while whole-blood samples were examined for pestiviral antigen and RNA by antigen ELISA and real-time RT-PCR, respectively. Epidemiological associations were evaluated using generalized estimating equations (GEE), with herd included as the clustering variable. Pestivirus antibodies were detected in 168 of 280 sheep, corresponding to an animal-level pestivirus seroprevalence of 60.00% (95% confidence interval (CI): 54.16-65.57). At the herd level, 14 of 16 herds (87.5%) had at least one seropositive animal, while herd-specific antibody seropositivity ranged from 0% to 82.76%. Four animals were antigen-reactive at the initial sampling, and one remained so at the 15-day retest; however, all samples were negative by real-time RT-PCR. Therefore, persistent infection could not be confirmed. In the multivariable GEE model, animal age, herd disease history, and the introduction of new animals into the herd were significantly associated with pestivirus seropositivity. Together with previous studies from Türkiye, our findings indicate that pestivirus exposure remains common in sheep populations and warrants continued regional surveillance. Serological screening should therefore be complemented by direct detection methods, including antigen ELISA and real-time RT-PCR, when investigating current or persistent pestivirus infection. Informing herd owners about pestivirus infections and appropriate biosecurity measures may also contribute to reducing their potential impact on animal health and production.