Sexual behaviors after universal screening of sexually transmitted infections in healthy young women.

Objective: To prospectively study the relationship between diagnosis of sexually transmitted infections (STIs) at entry to U.S. Marines recruit training and subsequent sexual behaviors during vacation.

Methods: Of all women entering recruit training (June 1999-June 2000), 2,157 (94%) voluntarily enrolled. At baseline, women received universal screening for Chlamydia trachomatis, Neisseria gonorrhoeae, and Trichomonas vaginalis and treatment and counseling for positive STIs. Recruit training (13 weeks) precluded any social activities. Unrestricted vacation followed (median 10 days). After training resumed (3 weeks), questionnaires and repeat STI screening were administered. Multivariable logistic regression examined STI diagnosis at baseline as a predictor for risky sexual behaviors at vacation and STI-positive diagnosis after vacation.

Results: The study was completed by 1,712 (79%) women (median age 18 years); 1,038 reported sexual activity during vacation; 71% used condoms inconsistently; 19% had casual partners. At baseline, 152 (15%) tested STI-positive. Baseline STI diagnosis was unrelated to inconsistent condom use, nonmonogamous partnerships, or multiple partnerships. However, women testing STI-positive at baseline were more likely to test STI-positive after vacation (adjusted odds ratio 3.74, 95% confidence interval 2.10-6.65). Baseline STI diagnosis predicted casual partnerships among women aged 19-21 years (adjusted odds ratio 2.48, 95% confidence interval 1.12-5.50).

Conclusion: Substantial numbers of women engaged in risky sexual behaviors after universal STI screening and counseling. Compared with STI-negative women, STI-positive women were at increased risk for subsequent STI acquisition regardless of their similar behaviors. As universal STI screening is increasingly implemented, follow-up care will likely be required to further reduce risky behaviors and address network-level factors.

Level Of Evidence: II.