Conference Coverage

Chlamydia prevalence is high, many infections go undiagnosed



ATLANTA – An estimated 1 in 15 sexually active adolescent girls has a chlamydial infection, and many of these infections go undiagnosed, according to an analysis of National Health and Nutrition Examination Survey data.

According to 2007-2012 NHANES data, the overall prevalence of chlamydia among sexually active adolescents and adults aged 14-39 years is 1.7%, suggesting that there are 1.8 million infections nationally, Elizabeth Torrone, Ph.D., reported in a poster at a conference on STD prevention sponsored by the Centers for Disease Control and Prevention.

CDC/Dr. E. Arum; Dr. N. Jacobs

This photomicrograph reveals McCoy cell monolayers with Chlamydia trachomatis inclusion bodies.

However, only 1.4 million infections are reported annually, according to information from the CDC, suggests that approximately 400,000 infections go undetected each year.

Adolescent girls – and particularly adolescent non-Hispanic black girls – are at highest risk, according to Dr. Torrone.

The estimated overall prevalence among adolescent girls aged 14-19 years in this study was 6.4%. The estimated prevalence among white girls in this age group was 3.2%, and among black girls in this age group it was 18.6%, reported Dr. Torrone of the division of STD prevention, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention at the CDC, Atlanta.

The overall prevalence was 1.4% among males, 2.0% among females, 2.4% among persons aged 14-19 years, 2.9% among those aged 20-24 years, 1.1% among those aged 25-39 years, 2.3% among Mexican Americans, 5.2% among non-Hispanic blacks, and 0.8% among whites.

Having multiple sex partners in the past year was associated with increased prevalence: 3.2% for those with two or more partners, compared with 1.4% among those with one or no partner.

NHANES respondents included in this analysis were 8,330 adolescents and adults aged 14-39 years between 2007 and 2012 who were tested for C. trachomatis using the Gen-Probe Aptima test. Prevalence estimates were based on demographics and self-reported sexual activity measured through audio, computer-assessed self-interviews.

Estimates were weighted to be nationally representative and to account for oversampling and nonresponse, and the number of infections in the population was estimated by multiplying census estimates by weighted prevalence, Dr. Torrone explained.

Chlamydia is the most commonly reported infection in the United States, and annual screening is currently recommended for all sexually active females under age 25 years, she noted.

Since the findings of this study likely represent an underestimate of the true burden of disease because the estimates do not account for nongenital infection and infections in nonsampled populations where prevalence may be higher (such as incarcerated individuals), they highlight a need for targeted interventions to reduce the impact of chlamydia among young African American women and underscore the importance of adhering to the screening recommendations.

"Health care providers should screen all sexually active young females annually and ensure that all sex partners of patients diagnosed with chlamydia are treated appropriately," Dr. Torrone concluded.

Dr. Torrone reported having no disclosures.

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