[Ornithosis--studies in correlation with an outbreak].

An outbreak of ornithosis with 8 cases of ornithosis pneumonia and 2 lethal complications was investigated in workers in a poultry farm and processing plant and a comparative seroepidemiological study of antigen responses was performed in 3 collectives: No. I: n = 82/87 workers in the processing plant, where the outbreak occurred; No. II: n = 83 workers in a chicken slaughter-house; No. III: n = 82 as matched-pair group to collective No. I with the same age and sex, but without occupational risk. The test systems were: genus specific complement fixation reaction (CFR), Ipazyme commercial slide kit containing LGV antigen and a type-specific microimmunofluorescence (MIF) technique with antigens binding C. psittaci, pneumonia and trachomatis IgA, IgG and IgM. 57/82 (71.9%) workers in group No. I were chlamydial antibody-positive, whereas only 22/82 of the population Nr. III--control group (odds ratio 6.2/3.2-12.3 p < or = 0.05). 16/83 (19.3%) of the workers in the chicken slaughterhouse had antibodies against chlamydia group antigens. 30/82 of the collective No. I had serological evidence of a recent or current infection with higher antibody titres in CFR and IPAZYME-Test and/or antibody response against IgA and IgM (MIF). 43.3% of the latter could be serologically detected as specific infections with C. psittaci. 10 of 18 (55%) workers employed in the recent 3 months had serological signs of an acute infection. There was no association between the point of contact with the poultry (live hang areas, slaughtery, evisceration, cooling carcasses) and the prevalence of antibody response. The possible routes of infection, inhalation of dried excretions or aerosols and via hand-to-mouth contacts are discussed. In specimens of cloacal swabs and faeces of the ducks chlamydiae could be found although the animals were asymptomatic. The results of this study demonstrate that in poultry plants, where ducks and other poultry living in an aqueous habitat are slaughtered and processed, a high risk of C. psittaci infection (70.2%) and ornithosis morbidity (25%) with a lethality of 8.3% can exist. Since the eradication of C. psittaci in poultry does not seem to be possible at the moment, preventive measures e.g. gloves, masks, information and medical examinations of the workers must be implemented in those slaughterhouses and plants where C. psittaci is suspected or common.