1. RTI International is a trade name of Research Triangle Institute www.rti.org Untreated chlamydial infection among adolescents and young adults in Baltimore, MD Elizabeth Eggleston, DrPH 1 ; Susan M. Rogers, PhD 1 ; Charles F. Turner, PhD 2, Anthony Roman, MA 3 ; Sylvia Tan, MS 1 ; Emily Erbelding, MD, MPH 4 (1) Statistics and Epidemiology, Research Triangle Institute, Washington, DC; (2) Queens College, City University of New York; (3) Center for Survey Research, University of Massachusetts-Boston; (4) Johns Hopkins University School of Medicine, Baltimore, MD. Presented at The 136th Annual Meeting of the American Public Health Association San Diego, CA October 25–29, 2008 Phone: 202.728.2080 Email: eeggleston@rti.org

2. Chlamydia Trachomatis (CT)  Most frequently reported bacterial sexually transmitted infection in the U.S.  348 cases per 100,000 population reported to CDC in 2006 – up 5.6% from 2005  Reported rate among women 3 times higher than among men

3. Chlamydia: morbidity  Among women, untreated chlamydia may result in pelvic inflammatory disease (a major cause of infertility, ectopic pregnancy, chronic pelvic pain)  Among men, CT associated with urethritis & epididymitis.  Untreated CT infections facilitate HIV transmission among both men & women

4. Chlamydia surveillance  Laboratories and medical providers required by law to report diagnosed cases of chlamydia.  Reported cases represent only those infections that are detected and, presumably, treated.  Chlamydia infections are usually asymptomatic; 75% women and 50% men have no symptoms.  Surveillance data reflect standard screening practices – CDC recommends testing all sexually active women under age 26 annually.

5. Monitoring STIs Survey Program (MSSP)  Continuous monitoring of three STIs (CT, Tv, GC) over three years in Baltimore, starting in 2006  Designed to address shortcomings of current surveillance methods (incomplete coverage, skewed in response to screening norms)  Funding provided by NICHD  Collaboration between RTI, Univ. of Mass-Boston, UNC- Chapel Hill, Johns Hopkins Univ. School of Medicine/BCHD

6. MSSP, continued  Data collection via TACASI interview and mailed-in urine specimens  Study participants: aged 15-35, male and female, English speaking

7. MSSP, Year 1 analysis  In Year 1 (Sept 06 – Aug 07), 1248 Baltimore residents aged 15-35 completed a TACASI interview; 69% (n=866) provided a urine specimen.  We calculate prevalence estimates of CT in the population.  We assess associations between demographic/behavioral characteristics and CT prevalence using chi-square tests.  We compare our study data to BCHD surveillance data.  All MSSP data are weighted.

8. MSSP: Estimated prevalence of chlamydia, overall and by gender and race

9. MSSP: Estimated prevalence of chlamydia by age group

10. MSSP: Estimated prevalence of chlamydia by marital status and education

11. MSSP: Estimated prevalence of chlamydia by risk factors

12. MSSP: Estimated prevalence of chlamydia by STI history

13. Surveillance data  Cases of CT infection reported to Baltimore City Health Dept. (BCHD) by medical providers and laboratories  Percentages for population prevalences calculated using 2000 U.S. Census reports of population size as denominator  Surveillance data grouped by age using U.S. Census age categories  MSSP data presented for comparison with same age categories

14. Surveillance data v. MSSP: Estimated chlamydia prevalence, ages 15-34

15. Surveillance data v. MSSP: Estimated CT prevalence, by gender and race

16. Surveillance data v. MSSP: Estimated CT prevalence, by age

17. Conclusion  Nearly 5% of 15-35 year-olds had an undetected chlamydial infection in MSSP.  CT prevalence slightly higher among males and among blacks, but small sample sizes limit generalizability of these findings.  Infections most prevalent among 18-23 year olds, those with least education  Having multiple partners strongly associated with CT infection, even as few as 2 in past year.  Previous infection strong predictor of current infection.

18. Conclusion, continued  Comparison of MSSP to surveillance data suggests that undiagnosed, untreated CT infections among 15-34 year-olds exceed diagnosed/reported infections by a factor of 1.3.  Ct prevalence in MSSP higher among males than females, while opposite pattern emerges in surveillance data -- suggesting need for increased Ct screening among males.