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Prevalence of chlamydia high among young adults in U.S.

The JAMA Network Journals

Approximately 4 percent of young adults in the U.S. have chlamydial infection, with substantial racial/ethnic disparities present in the prevalence, according to a study in the May 12 issue of The Journal of the American Medical Association (JAMA).

According to background information in the article, the sexually transmitted diseases Chlamydia trachomatis (chlamydia) and Neisseria gonorrhoeae (gonorrhea) cause substantial illness in the United States. In women, chlamydial and gonococcal infections may cause pelvic inflammatory disease, tubal infertility, chronic pelvic pain, and ectopic pregnancy. Chlamydial infection may also be linked to cervical cancer. Chlamydial and gonococcal infections may increase susceptibility to and transmission of human immunodeficiency virus in both men and women. Early detection and treatment of these infections is challenging because most women and men with chlamydial infection and many women with gonorrhea are asymptomatic. Although screening for chlamydia is widely recommended among young adult women, little information is available regarding the prevalence of chlamydial and gonococcal infections in the general young adult population.

William C. Miller, M.D., Ph.D., M.P.H., of the University of North Carolina at Chapel Hill, N.C., and colleagues conducted a study involving a nationally representative sample of 14,322 young adults aged 18 to 26 years. In-home interviews were conducted across the United States for Wave III of The National Longitudinal Study of Adolescent Health (Add Health) from April 2, 2001, to May 9, 2002. This study sample represented 66.3 percent of the original 18,924 participants in Wave I of Add Health. Urine specimens were available for 12,548 (87.6 percent) of the Wave III participants, and were tested for evidence of chlamydial and gonococcal infections.

The researchers found that the overall prevalence of chlamydial infection in this sample of young adults was 4.19 percent. Prevalence varied little by age, but was more common among women (4.74 percent) than men (3.67 percent). Prevalence was more than 2 times higher in the south (5.39 percent) than in the northeast (2.39 percent) region.

The prevalence of chlamydial infection varied significantly by race/ethnicity. Prevalence was lowest in white young adults (1.94 percent) and more than 6 times higher in black young adults (12.54 percent). Intermediate prevalences were observed in Latino young adults (5.89 percent). The highest prevalence in any group was among black women (13.95 percent), followed by black men (11.12 percent). The lowest prevalences were among Asian American men (1.14 percent), white men (1.38 percent), and white women (2.52 percent).

Overall prevalence of gonorrhea was 0.43 percent. Among black men and women, the prevalence was 2.13 percent and among white young adults, 0.10 percent. Overall, the prevalence of co-infection with both chlamydial and gonococcal infections was 0.03 percent.

"The high prevalence of chlamydial infection in both men and women suggests that current screening approaches that focus primarily on clinic-based testing of young women are inadequate. The reduction of disparities in the prevalence of both chlamydial and gonococcal infections across racial/ethnic groups must also be a priority," the authors conclude.


(JAMA. 2004;291:2229-2236. Available post-embargo at

Editor's Note: For information on the funding of the study, please see the JAMA article.

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