Pasteurella haemolytica Found in the Respiratory Tract of Fowl

Abstract

SUMMARY An incidence of Pasteurella haemolytica of 97% in the tracheal flora of 322 healthy chickens from 23 flocks was in contrast to its low incidence (3%) or absence in the tracheal flora of 91 healthy turkeys from eight flocks and 32 ducks from three flocks. This organism was infrequent or absent in the specimens from the trachea of nondomestic birds. In a collection of 68 P. haemolytica strains from cases of respiratory disease in poultry, the number of isolations was significantly high from chickens (87%) by comparison with isolations from turkeys (9%) and geese (4%). The biochemical characteristics and virulence of the P. haemolytica isolated did not appear to differ between healthy birds and birds with clinical symptoms. It is postulated that P. haemolytica is a member of the normal flora of the respiratory tract of chickens but not of turkeys or ducks. Under conditions of stress, however, this bacterium may acquire the role of an opportunist, participating in pathological processes.