[Anti-Legionella pneumophila antibody titers in blood from children and adults with lung diseases of unknown etiology].

175 sera from children and 101 sera from adults both with respiratory illness of unknown origin were collected between September 1980 and February 1983 and studied by using the indirect immunofluorescence test for Legionnaires' disease. By using the criteria of the Center for Disease Control for a positive (fourfold increase in titer over 128 during convalescence) or presumptive (single titer greater than or equal to 256) serological test, 8 samples from adults (7.92%) and 11 samples from children (6.27%) gave a positive result. These results suggest that the frequency of Legionnaires' disease is similar in both adults and children.