Effect of bovine virus diarrhoea-mucosal disease virus infection on salmonella infection in calves.

The possibility that bovine virus diarrhoea virus (BVDV) infection could aggravate concurrent salmonella infections was investigated in two series of experiments with Salmonella dublin and S typhimurium. In both series of experiments the clinical signs tended to be more severe in dual infections than in those with salmonella alone. Faecal excretion of S dublin was similar in both single and dual infected calves. A protracted bacteraemia occurred only in two dual infected calves, one of which died from suppurative meningitis. In the case of S typhimurium, body temperatures, passage of abnormal faeces and isolation rates of salmonella from faeces were significantly increased. The results suggest that BVDV infection may indeed exacerbate the effects of salmonella infection and the aetiological relationship of the two agents should be considered during outbreaks of bovine salmonellosis.