Seroprevalence of bovine viral diarrhea virus and detection of persistently infected (PI) animals in dairy farms of Holeta, central Ethiopia

Abstract

Bovine viral diarrhea virus (BVDV) is one of the most important pathogens of the reproductive systems that have a significant  socio economic impact on the dairy industry. A cross-sectional study was conducted on 17 randomly selected farms out of 133 registered  dairy farms in Holeta, a town in the Walmera district of Ethiopia. The study aimed to detect BVDV antigen-positive animals and investigate  the seroprevalence of BVDV infection. A total of 337 serum samples were collected from selected farms with no history of  BVDV vaccination. The indirect enzyme-linked immunosorbent assay (I-ELISA) test was the screening test used to detect antibodies  against BVDV. In contrast, antigencapture ELISA was used for the detection of BVDV antigens in seronegative animals. A logistic  regression model was used to assess the association between potential predictors and BVDV exposure. The overall animal level  seroprevalence was 15.4%, and 64.7% of the herds had at least one seropositive animal. From 285 seronegative animals, one animal  (0.4%) was found positive for BVDV antigen. The same animal was found positive in a double check 21 days later. In this study, cows with  a history of abortion (OR = 6.3; 95% CI: 1.61 -13.1), history of repeated breeding (OR = 7; 95% CI: 2.5 - 14.3), animals managed intensively  (OR = 4.6; 95% CI: 1.6 - 13.0) and multiparous cows (OR = 3.6; 95% CI: 1.5 - 8.9) had higher proportion of seroreactors in their respective  comparison category (p<0.05). Besides, cows with a history of congenital defective calve birth (OR = 15.2; 95% CI: 3.2 - 73.6), adult age  groups (OR = 2.9; 95% CI: 1.0-7.9), and cows bred both artificially and natural mating (OR = 4.6; 95% CI: 1.7 - 12.6) were statistically  associated with BVDV seropositivity (p<0.05). In conclusion, this report demonstrated the presence of persistently infected (PI) dairy cattle  in Ethiopia. Thus, the findings warrant the need for immediate control intervention that involves both screening and culling of PI   animals and vaccination.