Is there immunity to chlamydial infections of the human genital tract?

Chlamydia trachomatis is commonly found in the urethra of men with gonococcal urethritis. Studies report a 20%-40% rate of double infection. A two-year study of men attending a venereal disease clinic in California showed that only 4% (4/99) or 7% (10/147) of men with gonorrhea had concomitant chlamydial infection, whereas 25-31% of the men with nongonococcal urethritis (NGU) had chlamydial infection. Men with gonorrhea seemed to have substantial recent exposure to chlamydial infection, since C. trachomatis was isolated from the cervix of 20% (36/180) of female contacts. Microimmunofluorescence (micro IF) tests showed that 93.6% (131/141) of the men with gonorrhea had IgG antibodies to Chlamydia and 36% (51/141) had IgM antibodies. IgG antibody rates were higher than those found among men who had NGU or no urethritis (83% and 65%, respectively), a fact which suggests that in this clinic setting the men with gonorrhea had very high antecedent exposure to C. trachomatis and may have been resistant to reinfection.