Prevalence of Stocker Calves Persistently Infected with Bovine Viral Diarrhea Virus in the Southeast Determined Using Immunohistochemistry on Skin Biopsies
Type of DegreeThesis
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Bovine viral diarrhea virus (BVDV) is an insidious disease affecting cattle worldwide. It can cause early embryonic death, congenital defects, abortions, respiratory disease, immunosuppression, reproductive failure and may cause mortality. Animals that are born persistently infected (PI) with BVDV are considered the direct viral reservoirs that shed copious amounts of virus into the environment through aerosols, mucus secretions and fecal matter. Stocker calves from auction markets in the Southeastern USA (Alabama, Florida, Georgia, Mississippi and Tennessee) were sampled from March to December 2005. Once organized into average weight groups, the calves were processed and skin biopsies were collected in zinc buffered formalin for the detection of BVDV persistent infection using immunohistochemistry. Twenty four BVDV positive calves were detected of the 7,544 calves sampled. Confirmation testing at a later date was not an option in this study. The overall BVDV-PI prevalence rate of stocker calves sampled in the Southeast was estimated at 0.3%. This prevalence rate compared closely, if not less than, other PI prevalence rates reported in other areas of the U.S. In addition, calves in the less than 400 lbs. weight group had a 2.78 times higher probability of having a PI animal present when compared to the greater than or equal to 400 lbs. weight group. Therefore, a PI prevalence rate of 0.3% was found in stocker calves sampled from the Southeastern U.S. and the low weight groups less than 400 lbs. had a 2.78 times greater chance of having a PI animal in that group when compared to the heavier weight groups.