Fowl cholera epornitic: antigenic characterization and virulence of selected Pasteurella multocida isolates.

An epornitic of fowl cholera involving turkey flocks of several farms within a 15-mile radius in Utah was studied. Pasteurella multocida strains isolated from birds in affected flocks were antigenically characterized as A:1, A:3, and B:4, based on capsular serogrouping and somatic serotyping results. Experimental exposure of poults with each of two strains representing the rarely reported capsular group B indicated that both were virulent.