Abstract
Serological tests for chlamydial infection are one of the most frequently used methods in the diagnosis of atypical respiratory infections. Use of serological tests has implicated chlamydial infections in asthma, arthritis and coronary heart disease, but the specificity of chlamydial serology tests has been questioned. The immunofluorescence test is the most sensitive and specific serological test available for detection of chlamydial antibodies. This study compares two commercially available immunofluorescent antibody tests. The SeroFIA test using purified elementary bodies of Chlamydia pneumoniae, C. psittaci and C. trachomatis, detected 24 cases of acute C. pneumoniae infection, whereas the Spot IF test using whole cell antigen of C. psittaci and C. trachomatis, misdiagnosed 20 of these as psittacosis and missed four cases.