Studies on Pasteurella gallinarum

In two outbreaks of disease in chickens associated with Pasteurella gallinarum infection swollen and inflamed wattles were symptoms. A bacteriological study was carried out of 42 P. gallinarum strains isolated from the two outbreaks and from sporadic cases in fowls. Serotyping by the gel diffusion precipitin test indicated that all five strains from one outbreak and 82% of isolants from 22 sporadic cases belonged to one serotype, antigenically unrelated to Pasteurella multocida. All four isolants from another outbreak were of a different serotype and were antigenically related to P. multocida serotypes 6 and 9. Significant titres of agglutinating antibodies against hyaluronidase-treated P. gallinarum antigens and precipitating antibodies were detected in sera from chickens infected under field conditions and experimentally.