An occurrence of avian influenza virus infection in laying chickens.

The isolation of avian influenza virus from chickens is reported for the first time in the United States since the fowl plague outbreak of 1929. The type-A virus was isolated from commercial Leghorn laying hens between 54 and 55 weeks old and involved three different farms in north-central Alabama. These flocks experienced up to 69% mortality and a severe decrease in egg production within a 14-day period.