Characterization and pathogenicity of Haemophilus paragallinarum serotype C in local chickens of Taiwan.

Two strains (Strains 39 & B) of Haemophilus paragallinarum were isolated and identified as serotype C by dot-blotting analysis in Taiwan in 1994. To identify their virulence and pathogenicity in Taiwanese local chickens, local chickens were inoculated via nostril with the isolates, and examined for 14 days. Clinical signs of swollen face, and nasal discharge were first seen at 24 hr after inoculation, and the infectivity of Strains 39 and B at 14 days after inoculation among the inoculated chickens was 50.0-71.4% and 55.6-77.8%, respectively. From the results, we concluded that the two bacterial isolates were pathogenic to local chickens with a maximum morbidity of 77.8%.