Abstract
In September of 1988, nine 7-day-old nursing piglets in a litter of a farm in Niigata Prefecture suddenly showed depression and anorexia. Moreover, two of the nine piglets moved in circles in one derection with frothy fluid. One of the two died and another was dying on that day. After 3 days, their dam died without clinical sign. Those two piglets and their dam were examined.
On autopsy, the three pigs had similar lesions. A large mount of straw colored fluid and fibrin were present in their peritoneal cavity. Histopathologically, suppurative fibrious serositis was observed. No viruses were isolated. Pasteurella multocida (Pm) serotype A: 3·4 was isolated in pure culture from their hearts, lungs, livers, spleens, kidneys and brains. The disease was diagnosed as suppurative fibrious serositis caused by infection with serotype A: 3·4 strain of Pm. The median lethal does (LD50) of the isolate in mice was 101.2 colony-forming units.
An indirect hemagglutination test demonstrated the antibody against the Pm isolate in 177 (97.3%) of 182 pigs on the farm where the outbreak occurred and in 298 (82.8%) of 360 pigs on the 67 other farms of Niigata Prefecture. The antibody titers ranged from 4 to 256 on the former farm and from 4 to 64 on the latter.
