Outbreak of infectious bursal disease associated with acute septicaemic colibacillosis in adult prelayer hens

An outbreak of infectious bursal disease (IBD) occurred concurrently with acute septicaemic colibacillosis in 15 week old prelayer hens. The septicaemia was preceded by a subclinical IBD. Mortality in the outbreak began with lesions of septicaemia and Escherichia coli was isolated from the heart blood of the birds. After antibiotic treatment of the bacteraemia, mortality continued, spiked, declined and then ceased. IBD was confirmed by bursal lesions characterized by severe lymphocytolysis and cystic degeneration of the lymphoid follicles. Out of 253 birds, 42 (16.60%) died within eight days. The circumstances of the outbreak suggested that lack of IBD booster vaccination favoured the establishment of subclinical IBD, which suppressed immunity to predispose the birds to colisepticaemia.