Sera from nine out of 30 (30,0 %) apparently healthy unvaccinated indigenous (Tswana) chickens had
precipitating antibodies to infectious bursal disease (IBD) virus using the agar gel precipitation test.
Similarly, sera from 11 out of 49 (22,4 %) chickens of exotic breeds with no history of vaccination against
IBD were positive for antibodies against the virus.
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