Prevalence and risk factors of asymptomatic chlamydial infection among students in Japan.

The objective was to determine the prevalence of asymptomatic Chlamydia trachomatis infection (CTI) among students in Japan, and to examine risk factors and methods of prevention. A total of 1004 students were analysed. Urine samples were checked for chlamydial DNA using polymerase chain reaction techniques. Prevalence of CTI was 8.3%. Risk factors were age and a history of four or more sexual partners for females, and history of CTI and contact with new sexual partners for males. Age did not represent a risk factor for male students. A correlation was identified between history of genital infection and experience with commercial sex workers for male students. Sex education programmes should be implemented encouraging use of condoms not only by students over 18 years, but also by senior high school students. Development of efficient and practical screening systems tailored to the current status of school health management in Japan is also needed.