Pulmonary clearance and lesions of lung and air sac in passively immunized and unimmunized turkeys following exposure to aerosolized Escherichia coli.

Two groups of young turkeys, one passively immunized with homologous hyperimmune serum and the other unimmunized but receiving normal turkey serum, were aerosolized with Escherichia coli. Clearance of bacteria from lung and gross and microscopic lung and air-sac lesions were determined after necropsy at timed intervals. The group mean bacterial count in lungs of passively immunized turkeys was significantly less than the mean count in unimmunized turkeys. Lung lesions were generally similar in both groups and were focused in lymphoid nodules, at the junction of primary and secondary bronchi, and at the ostia to the air sacs. Unimmunized birds developed grossly evident purulent airsacculitis by 72 hours after aerosol exposure, whereas passively immunized birds did not.