Increase in sexual risk behavior and prevalence of Chlamydia trachomatis among adolescents in Northern Thailand.

BACKGROUND

Monitoring changes in adolescent sexual risk behaviors and sexually transmitted infections is critical for evaluating the effectiveness of human immunodeficiency virus and other prevention programs, but population-based data on adolescents in Thailand are limited. We report findings from 2 cross-sectional surveys conducted in 1999 and 2002 among 15-to 21-year-old vocational students.

METHODS

In 1999 and 2002, 1725 and 966 students, respectively, were interviewed using computer-assisted self-interview methods. Urine samples were collected and tested for Chlamydia trachomatis and Neisseria gonorrhoeae by polymerase chain reaction.

RESULTS

From 1999 to 2002 C. trachomatis prevalence increased from 3.2% to 7.5% (P <0.001) in women and from 2.5% to 6.0% (P <0.001) in men. There was an increase in the reported mean lifetime number of steady sexual partners among both men (3.4-4.7, P = 0.01) and women (2.5-3.3, P <0.001), and in the mean lifetime number of casual partners among men (1.1-2.1, P <0.001) and women (0.3-1.1, P = 0.04). Reported consistent condom use decreased significantly among women with casual partners (43%-19%, P = 0.03) but not among men (25%-31%, P = 0.31).

CONCLUSIONS

Our study identified important increases in the prevalence of chlamydial infection and in sexual risk behaviors among Thai adolescents over a 3-year period. These findings are consistent with other studies suggesting profound social changes are changing norms of adolescent sexual behavior in Thailand, and highlight the need for adolescent sexual health services and prevention programming.