Incidence and distribution of "avian adenovirus group II splenomegaly of chickens".

Forty-six percent of 3,585 serum samples from 174 broiler-breeder chicken flocks in 9 states were positive for the precipitating antibody of hemorrhagic enteritis (HE) of turkeys/marble spleen disease (MSD) of pheasants. Seroconversion was detected only in flocks 19 weeks of age and older. The percent of individual serum samples positive within a flock increased with the age of the flock.