Porcine parvovirus infection in a commercial piggery

We have recently been involved in a consultative role with a 60-sow commercial piggery. Over the year preceding the incident recorded here, this unit had approximately doubled in size by the purchase of improved large white gilts. An infertility problem involving irregular returns to service and small litter sizes was first noted around Christmas 1984. In early January 198.5 all the adult stock were bled and serological tests undertaken. There was no evidence of infection with Aujeszky`s disease virus or leptospires, but 42 sows had haemagglutination inhibition (HI) titres of >320 against porcine parvovirus (PP), and were considered to have been actively infected. Seventeen other gilts and sows in their second pregnancy had titres ≤320 and were considered to be still susceptible to infection. These animals were bled again 75 days later and HI tests on the paired sera showed that 15 of the 17 had now seroconverted (minimum titre 1,280). Eleven of these animals were in early to mid-pregnancy during the period of seroconversion. Five of these animals subsequently failed to farrow, and the remaining six produced a mean of only 6.5 (SD. 2.8) live piglets at birth. In contrast the two animals which did not seroconvert, and four other previously infected gilts with HI titre of 110,240 at the first bleeding, produced a mean of 9.8 (S.D. 1.7) live piglets. This was considered a satisfactory live birth rate…