Submitted to: Canadian Journal of Veterinary Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/7/2008
Publication Date: 10/20/2009
Citation: Fulton, R.W., Whitley, E.M., Johnson, B.J., Ridpath, J.F., Kapil, S., Burge, L.J., Cook, B.J., Confer, A.W. 2009. Prevalence of Bovine Viral Diarrhea Virus (BVDV) in Persistently Infected Cattle and BVDV Subtypes in Affected Cattle in Beef Herds in South Central U.S. Canadian Journal of Veterinary Research. 73(4):283-291. Interpretive Summary: Bovine viral diarrhea virus (BVDV) is an economically important pathogen of cattle. One of the main ways in which BVDV is introduced to herds is by exposure to an animal that is persistently infected (PI) with BVDV. Thus BVDV control efforts focus on preventing the introduction of PI animals into herds and the detection and elimination of any PI animal that is present in a herd. In this study 4,530 calves from 30 different herds were tested for persistent infection. The goal of this testing was to determine the prevalence of PI cattle in these herds and to examine the routes of introduction of PI cattle into herds. The results of this study suggest two important management considerations for ranchers and their veterinarians relating to BVDV control. First, there was a strong association between the presence of PI animals and the purchase of pregnant females. For this reason is it suggested that new additions to the herd should be purchased as BVDV test negative, and if pregnant, the heifers'/cows' calves should be tested for BVDV persistent infection soon after birth. Second, an effective BVDV vaccination program, which would included pre-breeding and calfhood vaccinations, should be stressed.
Technical Abstract: The prevalence of bovine viral diarrhea virus (BVDV) persistently infected (PI) cattle in beef breeding herds was determined in 30 herds with 4530 calves. The samples collected by ear notches were tested for BVDV antigen using immunohistochemistry (IHC) and antigen capture ELISA (ACE). Animals with initial positives on both IHC and ACE were sampled again for both tests, and serums were collected for viral propagation and sequencing of a viral genomic region, 5'-untranslated region (5'-UTR) for viral subtyping. Samples were also collected from the dams of PI calves. There were 25 PI calves from 4530 samples (0.55%) and these PI calves were from 5/30 herds (16.7%). Two herds had multiple PI calves and three herds had only one PI calf. Only 1/25 PI calves' dam was PI (4.0%). The subtype of all the PI isolates was BVDV1b. Histories of the ranches indicated 23/30 had herd additions of untested breeding females. Twenty four of 30 herds had adult cowherd vaccinations against BVDV using primarily killed BVDV vaccines at pregnancy examination.