Seroprevalence and risk factors associated with bovine herpesvirus 1 (BHV-1) infection in dairy cattle in southern and central Ethiopia.

Bovine herpesvirus 1 (BHV-1) is an important pathogen of cattle with a worldwide distribution. It occurs as a subclinical, mild or severe disease. The clinical signs may vary widely with respiratory, genital, ocular and encephalomyelitis form. This cross-sectional study was carried out between May 2019 and March 2020 with the aim to estimate the seroprevalence of bovine herpesvirus 1 (BHV-1) and to identify related potential risk factors in dairy cattle in central and southern Ethiopia. A total of 954 serum samples were obtained from randomly selected dairy cattle in 98 herds. The samples were collected from animals over 6 months old and tested using a BHV-1 antibody blocking enzyme linked immunosorbent assay (b-ELISA). The study showed that the animal- and herd-level seroprevalence of BHV-1 was 30.0 % (95 % CI: 21.7, 39.9) and 75.5 % (95 % CI: 65.9, 83.1), respectively. Multiple logistic regression model demonstrated that adult animals (> 2.5 years) (OR = 2.4, 95 % CI: 1.1, 5.5) had higher seroprevalence of BHV-1 compared to their counterparts (p < 0.05). Cattle in farms using artificial insemination (AI), and both AI and bulls had a 3.9 (95 % CI: 1.2, 13.3) and 5.1 (95 % CI: 1.8, 14.8) odds of being seropositive, respectively, compared to farms using bulls only. Arrangement of animals in a tail-to-tail fashion appeared to be protective against BHV-1 infection (p < 0.05). However, source of the animal was not associated with BHV-1 serostatus (p > 0.05). The animal- and herd-level prevalence recorded in our study confirms that BHV-1 infection is widespread and remains endemic in dairy cattle of central and southern Ethiopia.