Abstract
Isolation of Haemophilus pleuropneumoniae (Hpn) from nasal cavities of healthy pigs was investigated. The organisms produced typical transparent and smooth colonies with iridescence on the S agar medium. Isolation was done according to the growth chracteristics. A total of 293 Hpn strains (47.3%) was isolated from 619 pigs housed on 87 farms in different geographic districts of Japan during 1982/83. The organisms were isolated from all ages of pigs, and they were distributed in varying rates (20% to 100%) among the 87 farms. The organisms appeared to be one of common bacteria present in the upper respiratory tract of pigs. All the isolates were identified as serotype 2, therefore, the serotype 2 strains of Hpn were distributed widely among pigs in recent Japanese field as a clinically inapparent carrier state. Significant correlation (P<0.01) was observed between the presence of Hpn in nasal cavities and positive complement-fixation (CF) antibodies in pigs. The prevalence of Hpn among live pigs can be estimated by the CF test instead of the bacterial isolation test. The CF test might be useful for detection of the carrier pigs.
