Prevalence of antichlamydial antibody in London blood donors.

The prevalence of type-specific antichlamydial antibody in a population of blood donors in London was studied using a microimmunofluorescence test. Twenty-six (17%) of 150 women and 38 (26%) of 150 men had antichlamydial antibody (IgG at greater than or equal to 1/16 or IgM greater than or equal to 1/8 or both). Of these, five (3%) women had one (0.75%) man had this antibody directed against Chlamydia trachomatis serotypes D-K, responsible for genital infections, and one man had antibody to Chlamydia psittaci agents. The remaining 57 men and women had antibody against an atypical chlamydial isolate designated Chlamydia IOL-207, which is iodine-negative and serologically distinct from both C trachomatis and C psittaci. The nature and location of infection by this agent are obscure. The results of this study suggest that the prevalence of sexually transmitted infection with C trachomatis serotypes D-K in a normal adult population in London is very low.