Abstract
The incidences of growth-agglutination (GA) and IgG-GA antibodies against Erysipelothrix rhusiopathiae were examined on sera collected from 12 slaughter pigs with chronic swine erysipelas (group A), 46 clinically healthy pigs which were housed with infected pigs on 11 farms (group B), and 188 clinically healthy slaughter pigs from 18 farms where chronic erysipelas had never been previously detected at slaughter (group C). In group A, GA and IgG-GA antibodies were very high titer, ranging from 1: 256 to ≥ 1: 2, 560 and from 1: 128 to 1: 1, 280, respectively. There were no differences in the GA titer and positive rates of IgG-GA (1: 4 or above) between groups B and C, namely the former were 1: 25.1 and 1: 22.4 of geometric mean (GM), and the latter were 39.1% and 44.7%. The positive rate of IgG-GA on each farm of groups B and C varied from 0 to 100%. Eight pigs (4.3%) of group C possessed high IgG-GAtiters (1: 32 or more) suggesting that they might be infected naturally in the housing. This would mean that development of serum antibody is not enough due to retained maternal antibody derived from the vaccination.Erysipelothrix rhusiopathiae was isolated from 3 samples (2.7%) of a mixture of feces and bedding on 2 farms (4.2%). Serotypes of these isolates were 2, 5 and 7.
