Epidemiology of SwineActinobacillus pleuropneumoniaeInfection

Abstract

The serotypes ofActinobacillus pleuropneumoniae (APP) isolated from swine cases in the last 13 years were retrospectively studied and bacteriology of pneumonic lesions on slaughtered pigs and serology by complement-fixation test on swine farms were made in 1993 and 1994. All isolates before 1989 were of serotype 2, while serotype 5 in 1989 and serotypes 1 and 7 in 1994 were detected. Almost all the cases exhibited fibrinous pleuropneumonia, and in 1994 there were one case with meningitis due to serotype 7 and the other with verrucous endocarditis and arthritis due to serotype 2. In 1994, all the 12 isolates from 85 nodular abscess lesions in the lungs of slaughtered pigs were of serotype 2. Streptomycin resistant strains were isolated in 1984 and 1989 and the frequency of multiple drug resistant strains increased after 1992, and the serotypes 1 and 7 isolates were shown to have plasmids. Of 231 sera from 17 herds surveyed in 1993 and 1994, 9 sera from 4 herds, 84 from 12 herds, 1 from 1 herds, and 4 from 1 herds were positive for serotypes 1, 2, 5, and 7, respectively.