1. Sexual Behavior and the Prevalence of Chlamydia trachomatis Infection in Asymptomatic Students in Germany and Spain Christiane Stock 1, Francisco Guillén Grima 2, Luise Prüfer- Krämer 1, Inmaculada Serrano Monzo 3, Blanca Marin Fernandez 2, Ines Aguinaga Ontoso 3, Alexander Krämer 1 1 School of Public Health, University of Bielefeld, Bielefeld, Germany 2 Dept. of Health Sciences, Navarra Public University, Pamplona, Spain 3 School of Nursing, University of Navarra, Pamplona, Spain

2. Background u University students belong to the group of young sexually active persons that are at high risk for sexually transmitted diseases (STDs). u Chlamydia trachomatis is one of the most prevalent STDs in many industrialized countries. u There are only rare prevalence studies in unselected, asymptomatic populations involving men and women. u Students tend to underestimate their risk to acquire a STD and have a low acceptance of condoms.

3. Objectives The characterization of differences in patterns of sexual behaviors and prevalence of Chlamydia trachomatis infection in two samples of university students in Germany and Spain.

4. Materials and Methods Samples u188 asymptomatic students at the University of Bielefeld (UB), Germany Follow-up of a longitudinal students´ health study u590 asymptomatic students of the Universidad Publica de Navarra (UPNA), Pamplona, Spain Baseline study of a longitudinal students´ health study Self-administered questionnaire ustandardized, anonymous questionnaire in German, Spanish and Basque version Laboratory uFirst void urine samples, ligase chain reaction (LcX) method (Abbott)

5. Study Populations

6. Methods of Contraception in Females

7. Consequent Use of Condoms with a New Sexual Partner

8. Number of Sexual Partners in the Last 12 Months

9. Frequency of Sexual Intercourse (≥ 2 times per week)

10. Odds ratios for sexual behaviors and use of contraceptive methods in Spanish students compared to German students (reference group) adjusted for age, sex, and educational level of father

11. Prevalence of Chlamydia trachomatis Infection

12. Results u Spanish students were less likely to have more than one sex partner within the last 12 months and to have two or more times sexual intercourse per week. u They reported a lower use of oral contraceptives, a higher use of condoms, and were more likely to always use condoms with a new sex partner. u The prevalence of chlamydia infection was considerably higher in German students than in Spanish students, where no case was found.

13. Conclusions u It can be assumed that the higher prevalence in chlamydia infection in German students can be explained by the higher level of sexual activity and the lower use of barrier contraception in this group. u We recommend educational campaigns and other preventive measures in combination with the implementation of a selected screening program for chlamydia infection in Germany.  Further research is needed in Spain to monitor the chlamydia prevalence in the future.