Detection of bacteremia in cattle inoculated with bovine viral diarrhea virus.

Bovine viral diarrhea virus infection of cattle interfered with normal blood clearance mechanisms, as evidenced by the detection of an endogenous bacteremia in up to 85% of infected calves during the first 5 days after infection. The occurrence of detectable bacteremia correlated with the period of leukopenia and depression of lymphocyte responses to mitogens. Noninoculated control animals, reinoculated immune calves, or calves inoculated with infectious bovine rhinotracheitis virus yielded consistently negative cultures. Bacillus spp were isolated in almost all calves. Similar organisms were isolated from the blood of normal calves when medium containing sodium poly-anetholesulfonate was used for culture. It was concluded that bovine viral diarrhea virus infection depressed the normal defense mechanisms, presumably humoral factors or phagocytic function, resulting in uninhibited blood circulation of bacteria during infection.