[Epidemiological study on Chlamydia trachomatis infection among sexually active female adolescents].

Sexual behaviour in 141 female adolescents, from 15 to 20 (average 17.4) years old, detained in a remedial institution was investigated from an epidemiological viewpoint, with special reference to Chlamydia trachomatis (CT) infection, from April, 1985 to March, 1986. All had experienced sexual intercourse. Nineteen subjects (13.5%) were found to be CT-antigen positive by either cell cultures (16 cases) or immunofluorescence tests (9 cases). The immunotypes of CT belonged to types D-K. CT-antigen was isolated more frequently (25.5%) from girls with uterine cervicitis than from those without inflammation (5.8%) (p less than 0.001). Younger girls seemed to be more susceptible to chlamydial infection, because CT-antigen was detected at a higher rate (21.1%) in the 15-17 year age group than in the 18-20 year group (4.6%) (p less than 0.01). Anti-CT IgG antibody (CT-antibody) was found in 65 sera (46.1%). CT-antigen was detected more frequently in CT-antibody positive girls than in those with negative tests (p less than 0.001). Such results suggest that serum antibody does not effectively prevent chlamydial infections in the genital tract. The duration of persistent chlamydial infection was estimated to be from 41 to 367 days, based on the period between the last intercourse and the latest CT-antigen positive day. CT-antigen disappeared spontaneously in some girls (9 of 15) during a 100 day period of abstinence.