[Bovine virus diarrhea virus infections in swine]

Since 1976 nineteen naturally occurring and eight experimentally induced incidents of congenital bovine viral diarrhoea virus (BVDV) infections were detected in routine laboratory diagnosis of swine fever. In nearly all naturally occurring cases, the disease was limited to one litter only. Clinical signs of disease and gross pathological lesions resembled those of chronic swine fever. Nearly all piglets born infected with the disease died within four months of birth. One pig remained persistently infected and immunotolerant until slaughtered at the age of 24 months; one of its litter mates seroconverted when six months old. In contrast, postnatal infections of pigs with BVDV strains isolated from swine ran a nearly or completely subclinical course. A serological survey of slaughter sows and boars showed that 20 per cent of the animals had antibodies against BVDV. The percentage of seropositive pigs was significantly higher on farms where cattle were present, and the percentage increased with age regardless of whether cattle were present. Sheep, pigs and humans can also transmit BVDV infections to pigs.