TYPE-II BOVINE VIRUS DIARRHEA VIRUS-INFECTION IN A CLOSED HERD OF SIMMENTAL CATTLE

This case report discusses the terminology associated with clinical fo rms of bovine virus diarrhea (BVD) virus infection and biotypes of the BVD virus. Eleven calves and 8 cows in a closed herd of 68 Simmental cattle died over an 8-week period during a disease outbreak in July-Se ptember 1993. The cows had been vaccinated with an inactivated BVD vir us vaccine approximately 2 to 3 years before the disease outbreak. The cows also received an inactivated BVD virus vaccine in the fourth wee k of the outbreak. A type II, noncytopathic BVD virus was diagnosed by virus isolation and serology. The virus caused severe clinical diseas e. In calves, the disease was marked by profuse salivation, liquid fec es, dilated pupils, fever, depression, anorexia, and death within 72 h ours. Cows consistently exhibited diarrhea, but the clinical course la sted 1 to 17 days. Thirty-nine percent of the calves and 27% of the co ws in the herd died; the case fatality rate was 85%. Recommendations w ere to isolate infected animals, increase the frequency of vaccination against BVD virus, and attempt to identify any persistently infected animals.