Case report

Detection and management of bovine viral diarrhea virus type 1b in a large dairy herd

Abstract

Bovine viral diarrhea virus (BVDV) continues to be a challenge for the cattle industry despite routine vaccination that includes killed or modified-live BVDV antigens. At a commercial dairy, 1,081 newborn calves were tested for BVDV antigen by pooled reverse transcription polymerase chain reaction as part of a screening program. Immunohistochemistry confirmed persistent BVDV infections in 13 calves. Ten of the PI calves were available for BVD typing. Both cytopathic and non-cytopathic BVD viruses were isolated. The non-CPE viruses typed as BVD type lb with a total of 3 different strains found; an identical strain found in 2 calves, another identical strain found in 2 other calves, and a third identical strain found in 3 other calves. A BVDV control program relying solely on BVD vaccination using a modified-live vaccine did not protect calves in this herd from persistent infection with type lb BVDV. These results demonstrate that control programs that rely only on vaccination to control BVDV without testing for the presence of PI animals are not adequate to control BVD.