Seroepidemiology of bovine alphaherpesvirus 1 (BoAHV-1) in commercial and smallholder dairy herds in north Shewa, central highlands of Ethiopia

Bovine alphaherpesvirus 1 (BoAHV-1) is the most important respiratory and reproductive disease-causing pathogen in dairy cattle. Despite BoAHV-1 has become widespread and a major challenge to the dairy industry, little is known about its epidemiology in dairy herds in Ethiopia. A cross-sectional study was conducted from November 2022 to May 2023 to determine the seroprevalence and potential risk factors associated with BoAHV-1 seropositivity in dairy herds in North Shewa, the central highlands of Ethiopia. A total of 511 blood samples were collected from randomly selected cattle herds (n = 142) and examined antibodies against BoAHV-1 using ELISA test. A retrospective survey was also done to gather information related to reproductive disorders. The overall seroprevalence of BoAHV-1 was 61.84% (95% CI: 57.53–65.97) at the animal level and 85.21% (95% CI: 78.28–90.21) at the herd level. Multivariable logistic analysis revealed that the risk of being BoAHV-1 seropositive was nine times higher in cows older than six years (OR = 9.16; 95% CI: 3.09–27.16; P = 0.000), five times higher (OR = 4.51; 95% CI: 1.23–16.53; P = 0.019) in cows with a history of abortion, three times higher (OR = 2.75; 95% CI: 1.72–4.22; P = 0.029) in cows with a history of retained fetal membrane, and three times higher (OR = 2.83; 1.86–9.31; P = 0.03) in animals with clinical signs of ocular and/or nasal discharge. This study demonstrates a significant circulating of BoAHV-1 in the dairy cattle population in study districts. Thus, a comprehensive approach that includes strict farm biosecurity and vaccination should be practiced for effective BoAHV-1 control and prevention and to promote the growing dairy industry in the central highlands of Ethiopia. •BoAHV-1 seroprevalence is high (85.21%) in commercial and smallholder dairy herds in North Shewa, central highlands of Ethiopia•Dairy cattle's BoAHV-1 seroprevalence correlates with age, indicating older animals are more likely exposed to the virus•Cows with abortion history had 5 times higher BoAHV-1 risk, while those with history of retained fetal membrane had 3 times higher risk