Serological survey of infectious bursal disease virus serotypes 1 and 2 in California turkeys.

The prevalence of two infectious bursal disease (IBD) viruses--serotype 1, of chicken origin, and serotype 2, of turkey origin--was studied in California turkeys. Serum samples were collected from 15 turkey flocks representing nine counties. The virus-neutralization test was used. Overall, only 15% of 342 samples were positive for serotype 1, whereas 89% were positive for serotype 2. However, 12 out of 15 flocks had a least one sample positive for serotype 1, and 14 out of 15 flocks had at least one sample positive for serotype 2. Flocks with antibodies to serotype 1 had low geometric mean titers (GMTs) (1.5 to 8.8) and low-to-medium prevalence rates (5 to 53.3%). Flocks with antibodies to serotype 2 had high GMTs (36.8 to 2048) and high prevalence rates (60 to 100%). Results of this study lead us to question the efficacy of IBD vaccination in turkeys.