Quantitation of natural antibodies to infectious bursal disease in Nigerian indigenous chickens.

Serum samples collected from 687 indigenous chickens located in small scattered groups in four states of Nigeria were examined for antibodies to infectious bursal disease (IBD) virus by the agar-gel precipitation (AGPT) and counterimmunoelectrophoresis (CIEOP) tests. 51 of the positive samples were further titrated by each of the two techniques. CIEOP detected more positive reactors (74.59%) than AGPT (58.95%). CIEOP also detected higher antibody levels among the reactors [geometric mean titre (GMT) of 51 samples was 23.02] when compared to AGPT. GMT of the same 51 samples was 21.8. The prevalence of antibodies to IBD virus in the indigenous chickens ranged from 64.7 to 77.7% CIEOP reactors between states. Since reports of IBD outbreaks among these chickens are rare unlike the situation among commercial poultry flocks, it was concluded that local chickens probably act as carriers of IBD virus.