Fatal BVD Virus-induced Disease

Role of Persistently Infected Animals

Abstract

Bovine virus diarrhea (BYD) virus has been recognized as a cause for an acute diarrheal disease of cattle and mucosal disease. However, the diagnosis of mucosal disease is reserved for a more chronic or wasting syndrome in which there may be extensive erosion of the oral mucosa, intermittent diarrhea, anorexia, dehydration and eventual death. Attempts to experimentally replicate these field cases of disease were uniformly unsuccessful even though viral isolates from fatal cases were used. Over the intervening years, a few pieces of the BYD virus puzzle were identified, but no clear picture emerged until very recently. I will briefly review these recent findings and indicate areas of research which are needed in order to develop effective strategies for the prevention of BYD virus-induced disease. It now appears that most fatalities associated with BYD infections alone were due to the superinfection of persistently infected animals. This common mechanism for disease production was obscured because of the widely different clinical presentations of the disease.