Laboratory diagnosis of bovine viral diarrhea virus infections

IN THE LAST 10 YEARS, research on bovine viral diarrhea virus (BVDV) has produced a much clearer understanding of the virus and the diseases it causes. A byproduct of these research efforts is the availability of high-quality diagnostic reagents and procedures. The inconsistent and contradictory results of BVDV testing in many diagnostic laboratories should be of concern only for the historical record. Cell culture contamination, a problem stemming mainly from fetal serum, has been adequately documented, and effective controls should now be in place to deal with this serious source of inaccurate data. Today, detecting BVDV is not difficult compared with other viral agents. The virus is simple to isolate from various clinical specimens, high-quality reagents for antigen detection are available, and antibody detection by serum neutralization tests is uncomplicated. Identifying infected animals is an easy matter if the proper samples are submitted to the laboratory. Unfortunately, misconceptions about BVDV still exist that impede the diagnosis of BVDV-induced disease. These include ideas such as that cytopathic BVDV is an important cause of disease and that acute BVDV infections rarely produce marked clinical signs. Granted there are situations in which the correlation between clinical disease and the viral infection is not obvious, but a systematic, disease-based approach can identify the problem. The correct approach may not be inexpensive, but neither is an ongoing BVDV problem. In this article, I describe the diagnostic tests now commonly used to identify BVDV. I then discuss which tests to use in specific clinical situations.