Prevalence of antibodies to infectious bursal disease virus serotypes I and II in 75 Ohio chicken flocks.

Serum samples from 75 Ohio layer flocks were tested for antibodies to infectious bursal disease virus (IBDV) serotypes I and II using a virus-neutralization test. Infectious bursal disease had been diagnosed in three of the 75 flocks. Antibody titers to serotype I were detected in 77% of the flocks, and antibody titers to serotype II were detected in 47% of the flocks. Of the eight flocks known to have been vaccinated using a serotype I IBDV vaccine, all had antibody titers to serotype I, and four had antibody titers to serotype II. Eleven of 17 known unvaccinated flocks had antibodies to serotype I, and seven had antibodies to serotype II.