Chlamydial and gonococcal infections are important causes of pelvic
inflammatory disease, ectopic pregnancy, and infertility. Although screening
for Chlamydia trachomatis 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.
To determine the prevalence of chlamydial and gonoccoccal infections
in a nationally representative sample of young adults living in the United
Design, Setting, and Participants
Cross-sectional analyses of a prospective cohort study of 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% of the original 18 924
participants in Wave I of Add Health. First-void urine specimens using ligase
chain reaction assay were available for 12 548 (87.6%) of the Wave III
Main Outcome Measures
Prevalences of chlamydial and gonococcal infections in the general young
adult population, and by age, self-reported race/ethnicity, and geographic
region of current residence.
Overall prevalence of chlamydial infection was 4.19% (95% confidence
interval [CI], 3.48%-4.90%). Women (4.74%; 95% CI, 3.93%-5.71%) were more
likely to be infected than men (3.67%; 95% CI, 2.93%-4.58%; prevalence ratio,
1.29; 95% CI, 1.03-1.63). The prevalence of chlamydial infection was highest
among black women (13.95%; 95% CI, 11.25%-17.18%) and black men (11.12%; 95%
CI, 8.51%-14.42%); lowest prevalences were among Asian men (1.14%; 95% CI,
0.40%-3.21%), white men (1.38%; 95% CI, 0.93%-2.03%), and white women (2.52%;
95% CI, 1.90%-3.34%). Prevalence of chlamydial infection was highest in the
south (5.39%; 95% CI, 4.24%-6.83%) and lowest in the northeast (2.39%; 95%
CI, 1.56%-3.65%). Overall prevalence of gonorrhea was 0.43% (95% CI, 0.29%-0.63%).
Among black men and women, the prevalence was 2.13% (95% CI, 1.46%-3.10%)
and among white young adults, 0.10% (95% CI, 0.03%-0.27%). Prevalence of coinfection
with both chlamydial and gonococcal infections was 0.030% (95% CI, 0.18%-0.49%).
The prevalence of chlamydial infection is high among young adults in
the United States. Substantial racial/ethnic disparities are present in the
prevalence of both chlamydial and gonococcal infections.