Bovine Viral Diarrhea Virus and Bovine Herpes Virus-1 in Dairy Cattle Herds in Fars Province, Southern Iran: Seroprevalence and Evaluation of Risk Factors.

Bovine viral diarrhea virus (BVDV) and bovine herpes virus-1 (BHV-1) have been known as the major pathogens with significant economic consequences on the cattle industry worldwide, including in Iran. In this cross-sectional study, the seroprevalences of BVDV and BHV-1 and their associated risk factors were investigated in dairy cattle farms of Fars province, Iran, where with 0.4 million head of cattle, mainly crossbred, is ranked the first in cow population in southern Iran. A total number of 420 cattle in 18 herds were randomly selected from three geographical regions (140 samples from each of the north, central, and south regions) and their serum samples were analyzed to detect antibodies to these viruses using a commercially available enzyme-linked immunosorbent assay kit. Chi-square test and logistic regression analyses were employed to investigate associations between risk factors and the seroprevalence of viruses. The overall seroprevalence rates for BVDV and BHV-1 were estimated at 91.67% and 77.87% at the herd level and 55.48% and 39.76% at the animal level, respectively. The only significant factor associated with the seroprevalence of both viruses at the herd level was found to be the literacy level of farmers (<0.05). The significant risk factors for both viruses in cattle were identified as geographical region, age, and breeding method by the univariate analysis (<0.05), while gender and farming system were determined as risk factors only for BHV-1 (<0.001). A significant relationship of concurrent infection with BVDV and BHV-1 (φ=0.268, <0.001) was recorded, and 28.6% of sera had antibodies to both viruses. The results of the present study demonstrated that BVDV and BHV-1 had a wide distribution in dairy cattle herds in southern Iran and highlighted the need for intensive surveillance and control strategies to reduce the risk of the spread of these viruses.