Seroprevalence of Chlamydia trachomatis among female adults in the United States: The National Health and Nutrition Examination Surveys
Abstract Background Chlamydia trachomatis is the most common nationally notifiable sexually transmitted infectious disease in the United States; however, the seroprevalence of C. trachomatis infection is unknown. Methods This cross-sectional study was conducted among 1725 females aged 18-39 years who provided serum and urine samples in the 2013-2016 National Health and Nutrition Examination Surveys (NHANES). Presence of anti-C. trachomatis Pgp3 IgG was determined using both an enzyme-linked immunosorbent assay (ELISA) and multiplex bead array (MBA). Weighted seroprevalence estimates were calculated. Correlates of seroprevalence were examined by multivariable Poisson regression. Results In 2013-2016, overall seroprevalence of C. trachomatis Pgp3 IgG was 30.0%(95%CI=25.5%-35.0%) as measured by ELISA and 29.4%(95%CI=25.8%-33.0%) as measured by the MBA assay. Overall agreement between tests was 87.1%(1503/1725). There was a high positive agreement by the MBA assay with current detection of chlamydia in urine (86%[36/42]), a past-year diagnosis of chlamydia (82%[27/33]), and a history of treatment for pelvic inflammatory disease (61%[37/61]). Seroprevalence of C. trachomatis Pgp3 IgG, as measured by MBA, was significantly higher among non-Hispanic Blacks (68.0%; aPR=2.7[95%CI=2.3-3.3]), Mexican Americans (30.9%; aPR=1.5[95% CI=1.2-1.9]), and other Hispanics (35.0%; aPR=1.9[95%CI=1.4-2.5]) as compared to non-Hispanic Whites (21.4%). Seroprevalence was also associated with a higher lifetime number of sexual partners and a younger age at sexual debut. Conclusion Both the ELISA and MBA serologic assays revealed a high prevalence of antibodies to C. trachomatis Pgp3 in young adult females in the U.S. household population. There were major racial/ethnic disparities in exposure to C. trachomatis, with increased vulnerability among non-Hispanic Blacks.