Occurrence of haemagglutination-inhibition antibodies against egg drop syndrome 1976 virus in broilers

From a total of 22 broiler flocks 347 serum samples were screened by the haemagglutination inhibition (HI) test and 114 (32.9%) were positive for antibodies to egg drop syndrome 1976 (EDS'76). The HI titres of the serum samples ranged from 2 to 9 log2 and the overall geometric mean titre was 3.9 log2. Of the serum samples 82.5% showed HI titres between 2(2) to 2(5) and the most frequent titre was 2(3). All the flocks were positive and the flock prevalence of HI antibodies ranged from 13.3 to 46.6 per cent. The age distribution of HI antibodies and their titres have also been recorded. The widespread prevalence of EDS'76 virus infection in broilers and its likely significance are discussed.