Serology of Legionnaires disease: comparison of indirect fluorescent antibody, immune adherence hemagglutination, and indirect hemagglutination tests.

An immune adherence hemagglutination (IAHA) test for the measurement of antibodies to Legionella pneumophila was developed and evaluated for the diagnosis of Legionnaires disease. Its sensitivity was compared to that of the indirect fluorescent antibody (IFA) test and a recently developed indirect hemagglutination (IHA) test. The sensitivity of the three tests appeared to be similar, with the IFA test giving slightly higher titers. Both the IHA and IAHA tests appear useful for the serodiagnosis of Legionnaires disease; the IAHA test has the advantage that it can be used with many other serological antigens.