Reproductive disease and congenital malformations caused by Menangle virusin pigs

Objective To describe a new syndrome characterised by embryonic mortalities , stillbirths, mummified foetuses and congenital malformations in a herd of intensively farmed pigs. Design Field observations, laboratory investigations and examination of bre eding records. Procedure Pathology examinations were performed on mummified and congenital ly deformed piglets during an outbreak of reproductive disease at a 2600 so w intensive piggery in New South Wales from April to October 1997. Reproduc tive performance was monitored during the outbreak and breeding records wer e examined retrospectively. Serum and tissue samples from pigs were tested for evidence of infection with known porcine pathogens and for a new virus, Menangle virus, isolated from stillborn piglets with deformities from the affected piggery in August 1997. Results Reproductive disease occurred sequentially in all four breeding uni ts at the affected piggery over a period of 21 weeks. The farrowing percent ages in each unit decreased from 80 to 82% before the outbreak to 63 to 78% during the outbreak and the number of live piglets per litter declined fro m a mean of 9.6 to 9.8 before the outbreak to 7.2 to 8.9 during the outbrea k. The proportion of affected litters (litters with less than six liveborn piglets) was highest (64%) in the sixth week of the outbreak. Mummified foe tuses, stillborn piglets with arthrogryposis, craniofacial deformities and degeneration of the brain and spinal cord, were observed along with occasio nal abortions. Sera from sows that produced affected litters contained neut ralising antibodies against Menangle virus and there was evidence that this virus had been introduced to the piggery in February 1997. Conclusions Reproductive disease in pigs due to Menangle virus was characte rised by stillbirths, mummification, embryonic death and infertility, along with abortions, skeletal deformities and degeneration of the brain and spi nal cord in affected foetuses and stillborn piglets.