Seroprevalence and risk factors associated with Bovine herpesvirus-1 in Türkiye

This cross-sectional study was conducted to determine the seroprevalence of Bovine herpesvirus-1 (BoHV-1) infection and to identify potential risk factors associated with BoHV-1 circulation in cattle raised under diverse production systems in the Eastern Anatolia Region of Türkiye. A total of 592 serum samples collected from 49 herds across 10 provinces were tested using a gB-ELISA. The results revealed a seropositivity rate of 70.95% at the animal level and 97.96% at the herd level, indicating widespread circulation of the virus in the region. Risk factors were assessed using a Generalized Estimating Equations (GEE) model. Seropositivity differed significantly among provinces (p = 0.002), suggesting that regional differences in herd management, animal movement intensity, climatic conditions, and production practices may be associated with variations in seropositivity rates. Age was significantly associated with seropositivity (p = 0.003), with animals aged 5-10 years exhibiting the highest seropositivity rate (%89.1). One of the most notable findings was the strong association between BoHV-1 seropositivity and the source of purchased animals: herds acquiring local animals had a 9.1-fold higher risk of infection compared to those purchasing imported cattle (p < 0.001), suggesting an association between regional animal movement patterns and BoHV-1 seropositivity. Univariable analyses demonstrated that several management-related factors-including milk yield level (p < 0.001), calf-rearing method (p < 0.001), milking system (p = 0.013), presence of a calf barn (p = 0.053), and visitor access (p = 0.07) were associated with seropositivity. In particular, the markedly higher seropositivity in calves suckled directly from their dams and in low-yield herds may be associated with differences in infection exposure and biosecurity practices. In conclusion, the findings demonstrate that BoHV-1 remains highly endemic in Eastern Anatolia, and that age, animal movement patterns, and management practices are significantly associated with viral seropositivity within herds. These results provide a critical evidence base for designing regional control strategies, strengthening biosecurity protocols, and developing risk-based vaccination programs aimed at reducing the burden of BoHV-1 in Türkiye's cattle population.