Title: Follow up study of sexually transmitted disease (STD), sexual practice and human immunodeficiency virus (HIV) serology in homosexual men attending an STD clinic.
Abstract: evaluated a whole inclusion assay for detecting IgG antibodies to Chlamydia trachomatis and found its value to be questionable.In 1975 Richmond and Caul' reported that this technique detects anti- bodies to both C psittaci and C trachomatis.I have also found this test to be genus specific, capable of detecting antibodies to both chlamydial species as well as to an atypical chlamydial strain (C IOL-207) now tentatively designated as a "TWAR" strain of Cpsittaci.TWAR agents appear not to be sexually transmitted but to cause respiratory disease in adults.Antibodies to these agents are common in human populations and have been detected in groups from Great Britain, western and eastern Europe, the Middle East, and Africa2 as well as from the United States of America.3Serological tests that detect genus specific chlamydial anti- bodies, such as inclusion assays and some enzyme linked immunosorbent assays (ELISAs) will give positive results with anti- bodies to TWAR agents.In one study we estimated that around 50% of antibodies detected by an inclusion assay were due to exposure to TWAR agents and not C tra- chomatis.4Schachter has also reported that repeat testing of serum samples from early antibody studies has shown that sero- conversions attributed to C trachomatis were actually due to cross reacting anti- bodies to TWAR agents.5Several kits are now commercially avail- able for detecting antibodies to C trachomatis.I would urge that the specificity of any serology test be considered carefully when evaluating the results obtained.