Severe outbreaks of respiratory disease in dairy herds caused by bovine respiratory syncytial virus

Abstract

Blood samples were collected from 6 herds, 408 cows/herd in the acute phase of respiratory disease and 3-4 weeks later during the convalescence period. Bovine respiratory syncytial virus was shown to be the cause of outbreaks of severe respiratory illness in dairy herds throughout Sweden during 1988-89. The diagnosis was made by comparison of paired acute and convalescent serum antibody titres. An ELISA, applying a monoclonal antibody (MAb) to bovine immunoglobulin IgG was used. To screen for the prevalence of the infection on a herd basis, the indirect ELISA- test was also used for bulk milk samples. 21 milk samples from clinically ill and 15 milk samples from apparently healthy herds were tested. The mean absorbance values for positive herds were 0.94 whereas it was 0.02, for negative herds. It was concluded that this test was a highly sensitive and rapid method to screen for the prevalence of respiratory syncytial virus infection on a herd.