Psittacosis outbreak in employees of a turkey-processing plant.

In June 1976, 28 employees of a Nebraska poultry processing plant had clinical onset of an illness compatible with psittacosis. The diagnosis was serologically confirmed in 22 patients by fourfold or greater changes in their complement fixation antibody titers, using a Chlamydia group antigen. Lack of serologic response in the remaining patients could not be readily explained by therapy differences, timing of serologic evaluation, or severity of clinical illness. The comparable attack rates in the various processing departments were consistent with an airborne infection. However, results of the investigation also suggested that workers having both frequent contact with turkey tissues and skin injuries were more likely to be infected than other processing workers. The cost of the outbreak for reimbursed medical costs, workmen's compensation, and lost wages was $19,000. A single turkey flock was implicated as the source of infection. This flock had been screened on a voluntary basis for evidence of infection prior to slaughter, using criteria developed by the United States Department of Agriculture. Although the preslaughter screening failed to detect psittacosis infection, two turkeys from the same flock which inadvertently had not been sent to slaught were subsequently found to be infected.