Untreated chlamydial infection among adolescents and young adults in Baltimore, MD, USA

Chlamydia is the most frequently reported bacterial sexually transmitted disease in the U.S. It is the leading cause of female infertility and is associated with epididymitis and infertility among men. Chlamydia may increase the likelihood of HIV/AIDS transmission in both sexes.

Reported rates of chlamydia reflect cases detected and treated by providers and laboratories. Substantial under-reporting of chlamydia is likely because most (50-75%) infections are asymptomatic and thus remain undetected and untreated.

The Monitoring STIs study monitors the prevalence of three sexually transmitted infections -- gonorrhea, chlamydia, and trichomoniasis -- among a probability sample of adolescents and young adults (15-35 years) in Baltimore, MD. The study uses telephone surveys combined with testing of self-collected mail-in urine specimens. Data collection began September 2006.

In this paper we report findings from the first year of survey sampling on the prevalence and correlates, demographic and behavioral, of untreated chlamydial infection. We also compare our survey results to the number of infections reported to Baltimore City Health Department (BCHD) during the same time period.

Preliminary Results.

1109 Baltimore residents, aged 15-35 years, were surveyed. 70% provided a urine specimen, and 4.8% tested positive for chlamydia. Prevalence was higher among black participants than among whites – 7.0% v. 1.5%. Unexpectedly, prevalence was also higher among males than among females – 6.1% v. 3.5% --suggesting the need for increased screening among males.

Analyses of BCHD data suggest that undiagnosed, untreated Ct infections among 15-35 year-olds exceed the number of reported and treated infections by a factor of 1.4.