Epidemiology of urogenital infections caused by Chlamydia trachomatis and outline of characteristic features of patients at risk.

A study of Chlamydia trachomatis infection was conducted in two stages on 15,656 subjects at urogenital clinics of the Faculty of Medicine and Surgery at La Sapienza University in Rome, the S. Anna Hospital in Turin, and the Niguarda Hospital in Milan. The overall incidence of the disease was 6.4% in patients examined throughout the whole study period. The rate of positive cases was 5.8% for the 5270 patients examined up to 1990, and 6.7% for the 10,386 patients examined from 1990 to 1992, showing an increasing trend. There was a much higher positivity rate in men (9.8%) than in women (6.0%); the difference was statistically significant. Of all patients, 60%, were asymptomatic. In symptomatic patients, C. trachomatis was present in 18.5% of cases of non-gonococcal urethritis and in 12.8% of cases of salpingitis. The highest incidence of C. trachomatis infection was in women who had begun sexual activity at an early age, (under 25 years in age), had several sexual partners and used intra-uterine contraceptive devices or spermicides or both.