Reactions of Human Sera to Chlamydia and Avian Mycoplasma

Two groups of human sera (each comprising approximately 100 specimens) were examined for chlamydial antibody by complement fixation and radioisotope precipitation tests. Persons in Group I had a history of frequent exposure to poultry; those in Group II did not. Results were similar with both groups of sera in both tests. Results indicate that low to moderate levels of chlamydial antibody are common in adult human populations and that such antibody may result from contact with a variety of chlamydial agents producing both subclinical and clinical infections. All sera were tested for antibody to avian mycoplasma. Approximately 16% of sera in Group I were positive in the plate test, but all were negative in the tube test. None of Group II sera were positive.