Seroprevalence of anti-Chlamydia trachomatis IgG in outpatients attending a sexually transmitted disease clinic in Italy.

Prevalence of anti-Chlamydia trachomatis specific IgG antibodies was evaluated in a sexually transmitted disease outpatient population composed of 741 heterosexuals, 470 males and 271 females, and of 147 homosexual-bisexual men. The prevalence rates were 60.0% in heterosexual males, 50.6% in females and 73.5% in homosexuals-bisexuals. A positive association between age and antibody prevalence was found in males. Among heterosexuals there is an increasing trend of seropositivity with number of partners during the previous year. A significant association between anti-chlamydial and anti-herpes simplex, type 2, antibodies has been demonstrated.