An epornitic of avian cholera in waterfowl and common crows in Phelps County, Nebraska, in the spring, 1975.

In the spring of 1975, many species of waterfowl and common crows (Corvus brachyrhynchos) were found dead in Phelps County, Nebraska. About 25,000 water fowl and at least 3,000 crows died in the epornitic. Few waterfowl were seen dying, but the crows experienced a chronic illness during which they became debilitated and were lethargic and dyspneic. Gross and microscopic lesions in the waterfowl were typical for acute avian cholera. The crows had dark, firm areas within the lungs, loosely adhered yellow fibrous material in the pericardial sac and air sacs and, occasionally, liver abscesses. Microscopically, focal purulent pneumonia was present and a fibrinopurulent exudate overlaid a granulomatous reaction on the heart and lung surfaces. Isolation of Pasteurella multocida serotype 1 confirmed the diagnosis of acute and chronic avian cholera in the waterfowl and crows, respectively.