Serological evidence of Bovine herpesvirus-1, Bovine Viral Diarrhea virus and Schmallenberg v irus infections in relation to reproductive disorders in dairy cattle in Ethiopia

摘要

Highlights ? Exposure of dairy cattle to three abortion causing viruses is described. ? Shmallenberg virus, BHV-1 and BVDV were widely distributed among dairy cattle in Ethiopia. ? SBV, BHV-1 and BVDV were associated with reproductive disorders. Abstract Reproductive disorders in dairy cattle have been noted to be common in urban and peri -urban dairy production system in Ethiopia. The available reports on the causes of these disorders, however, are not conclusive. A case-control study was designed to investigate the possible association of major reproductive disorders in dairy cattle with exposure status to bovine herpesvirus-1 (BHV-1), bovine viral diarrhea virus (BVDV) and Schmallenberg virus (SBV). Cows with history of abortion/stillbirth were considered as cases (n=204) while, those cows with no such history were taken as control (n=359). The serological screening tests used for all the three viruses were blocking enzyme linked immunosorbent assays (B-ELISAs). Of the total 563 samples tested 58.4%, 43.8% and 32.9% were positive for SBV, BHV-1 and BVDV, respectively. Significant difference between cases and controls were noted for SBV ( p =0.026) and BHV-1 exposures ( p ). The difference noted for BVDV serostatus was not significant ( p>0.05 ). The highest proportion (28.9%) of concurrent exposures was noted for BHV-1 and SBV, followed by SBV and BVDV (21.5%) and BHV-1 and BVDV (20.2%). Evidence of exposures to all the three viruses were detected in 14.4% of the animals. However, significant difference between cases (39.7%) and controls (22.9%) among cattle with multiple sero-positivity was noted only for BHV-1 and SBV ( p 0.001). Proportion of uterine infection ( p =0.002) and fetal membrane retention ( p =0.005) increased in BHV-1 seropositive animals, while repeat breeding was common ( p =0.034) among BVDV exposed ones. Seropositive animals to any of the three viruses were detected in all sampled areas and the proportion of cattle with BHV-1 and SBV exposure history had a higher risk to at least one type of the reproductive disorders mentioned compared to the corresponding sero-negative groups.