EXPOSURE OF CALVES TO AEROSOLS OF PARA-INFLUENZA-3 VIRUS AND PASTEURELLA-HAEMOLYTICA

  • 1 January 1983
    • journal article
    • research article
    • Vol. 47  (4) , 422-432
Abstract
The present study was undertaken to investigate whether sequential exposure to aerosols of parainfluenza-3 virus followed by P. haemolytica, or P. haemolytica followed by parainfluenza-3 virus, could lead to the production of pulmonary lesions in conventionally-raised calves. Twenty male calves with low serum antibody titers to both organisms were placed in 5 equal groups. Synergism of parainfluenza-3 virus and P. haemolytica was not demonstrated in any of the sequentially infected groups and pulmonary lesions were mild in all challenged calves. Clinical signs of disease were not present after exposure to parainfluenza-3 virus although the virus was repeatedly isolated from nasal secretions of all inoculated calves. Exposure to P. haemolytica produced a transient response which consisted of increased rectal temperatures and respiratory rates, with a mild neutrophilic leukocytosis and a mild left shift present 6 h postinoculation and returning to normal within 24 h. Results from this study suggest, although do not confirm, that reduced pulmonary clearance of inhaled P. haemolytica in parainfluenza-3 virus infected calves does not necessarily lead to production of severe pulmonary lesions and that previous exposure to aerosols of P. haemolytica may not enhance secondary parainfluenza-3 virus infection.