Ornithosis in poultry workers

An outbreak of ornithosis in duck workers in the winter of 1979 and spring of 1980 was discovered by the investigation of a cluster of cases in Norfolk. A serological survey showed that 61% of duck workers but only 23% of control poultry workers had chlamydia group antibody titres of greater than or equal to 1:8. Altogether 9% of duck workers in the survey had antibody titres greater than or equal to 1:32 and a clinical illness suggestive of ornithosis. The proportions of seropositive tests and clinical attack rates were highest in workers eviscerating ducks and lowest in farm workers. It is suggested that a clinical history of contact with poultry should be considered relevant in the diagnosis of ornithosis and that clinicians caring for poultry workers should consider the possibility of ornithosis as an occupational disease.