Epidemiology

Incidence

Chlamydia is the most common reportable STD in the United States. There are 3 million estimated cases of chlamydia in the U.S. each year.

The direct and indirect annual costs of chlamydial infection, including costs of treating complications, total $2.4 billion. Yet, this figure may not adequately represent the cost of the disease since many cases of chlamydia are asymptomatic or treated presumptively.

Prevalence

Chlamydia is a reportable STD in all 50 states. The female and male rate differential is partly attributable to screening practices. With the availability of new (urine-based) screening methods, it is likely that reported incidence in males will increase. Increases are at least in part due to increased testing with more sensitive tests.

Rates are highest among adolescents and young adults. Racial and ethnic minorities continue to be disproportionately affected by sexually transmitted diseases in the United States. These disparities may be, in part, because racial and ethnic minorities are more likely to seek care in public health clinics that report STDs more completely than private providers. However, this reporting bias does not fully explain these differences. Other contributing factors include limited access to quality health care, poverty, and higher prevalence of disease in these populations.

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Chlamydia positivity in CDC’s prevalence monitoring system differs in various populations and settings.

• Family planning clinics: 3.0%-14.2%
• Youth detention facilities: 6.3% -28.3%
• Indian Health Service: 7.4%-9.7%
• National Job Training Program entrants: 4.4% -16.8%

Chlamydia test positivity in regional Infertility Prevention Project family planning clinics has been relatively stable between 2002-2006.

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