Epidemiologic studies of the 1975 avian influenza outbreak in chickens in Alabama.

The epidemiology of the first reported non-fowl-plague avian influenza (AI) virus, A/Chicken/Alabama/75 (Hav4Neq2), isolated from chickens in the United States is discussed. The signs and pathologic changes have been described. The environment, nutrition, and stress factors are discussed as possible contributors to the disease syndrome observed in 3 commercial egg-laying flocks. Avian influenza antibody was demonstrated by agargel precipitation in convalescent chickens through 83 days postinfection. A serological survey of 321 additional poultry flocks was negative for antibodies against avian influenza. A survey was made by serology and virus isolation techniques on 387 wild free-flying birds that fed and roosted in the area. Wild waterfowl are discussed as a possible source of the AI virus.