title: Chlamydia trachomatis trends in the United States among persons 14 to 39 years of age, 1999-2008.
abstract: BACKGROUND
  We report the first population-based assessment of national trends in chlamydia prevalence in the United States.
  
  
  METHODS
  We investigated trends in chlamydia prevalence in representative samples of the U.S. population aged 14 to 39 years using data from five 2-year survey cycles of the National Health and Nutrition Examination Survey from 1999 to 2008. Prevalence estimates and 95% confidence intervals (CI) are reported stratified by age, gender, and race/ethnicity. Percent change in prevalence over this time period was estimated from regression models.
  
  
  RESULTS
  In the 2007-2008 cycle, chlamydia prevalence among participants aged 14 to 39 years was 1.6% (95% CI: 1.1%-2.4%). Prevalence was higher among females (2.2%, 95% CI: 1.4%-3.4%) than males (1.1%, 95% CI: 0.7%-1.7%). Prevalence among non-Hispanic black persons was 6.7% (95% CI: 4.6%-9.9%) and was 2.5% (95% CI: 1.6%-3.8%) among adolescents aged 14 to 19 years. Over the five 2-year cycles, there was an estimated 40% reduction (95% CI: 8%-61%) in prevalence among participants aged 14 to 39 years. Decreases in prevalence were notable in men (53% reduction, 95% CI: 19%-72%), adolescents aged 14 to 19 years (48% reduction, 95% CI: 11%-70%), and adolescent non-Hispanic black persons (45%, reduction, 95% CI: 4%-70%). There was no change in prevalence among females aged 14 to 25 years, the population targeted for routine annual screening.
  
  
  CONCLUSIONS
  On the basis of population estimates of chlamydia prevalence, the overall chlamydia burden in the United States decreased from 1999 to 2008. However, there remains a need to reduce prevalence in populations most at risk and to reduce racial disparities.
authors.affiliation: National Center for HIV/AIDS, Viral Hepatitis, STD and TB Prevention, Centers for Disease Control and Prevention, Atlanta, GA, USA.
authors.forename: S Deblina
authors.initials: SD
authors.lastname: Datta
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Torrone
authors.forename: Deanna
authors.initials: D
authors.lastname: Kruszon-Moran
authors.forename: Stuart
authors.initials: S
authors.lastname: Berman
authors.forename: Robert
authors.initials: R
authors.lastname: Johnson
authors.forename: Catherine L
authors.initials: CL
authors.lastname: Satterwhite
authors.forename: John
authors.initials: J
authors.lastname: Papp
authors.forename: Hillard
authors.initials: H
authors.lastname: Weinstock
mesh_terms: D000293:Adolescent; D000328:Adult; D001741:Black or African American / Q000706:statistics & numerical data; D002690:Chlamydia Infections / Q000453:epidemiology* / Q000208:ethnology; D002692:Chlamydia trachomatis / Q000472:pathogenicity*; D003430:Cross-Sectional Studies; D005260:Female; D054624:Health Status Disparities; D006801:Humans; D007246:Infertility / Q000453:epidemiology* / Q000208:ethnology / Q000382:microbiology; D008297:Male; D017058:Mexican Americans / Q000706:statistics & numerical data; D009749:Nutrition Surveys; D000292:Pelvic Inflammatory Disease / Q000453:epidemiology* / Q000208:ethnology / Q000382:microbiology; D011247:Pregnancy; D011271:Pregnancy, Ectopic / Q000453:epidemiology* / Q000208:ethnology / Q000382:microbiology; D015995:Prevalence; D014481:United States / Q000453:epidemiology; D044465:White People / Q000706:statistics & numerical data; D055815:Young Adult