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Trends in STDs in the United States



Chlamydia Positivity among 15- to 24-Year-Old Women Tested in Family Planning Clinics, by State, 1999 Chlamydia is the most commonly reported infectious disease in the United States and may be one of the most dangerous sexually transmitted diseases among women today. While the disease can be easily cured with antibiotics, millions of cases go unrecognized. If left untreated, chlamydia can have severe consequences, particularly for women. Up to 40 percent of women with untreated chlamydia will develop pelvic inflammatory disease (PID), and one in five women with pid becomes infertile. Chlamydia also can cause prematurity, eye disease, and pneumonia in infants. Moreover, women infected with chlamydia are three to five times more likely to become infected with HIV, if exposed. Seventy-five percent of women and 50 percent of men with chlamydia have no symptoms. The majority of cases therefore go undiagnosed and unreported. The number of reported cases-about 660,000 cases in 1999-is merely the tip of the iceberg.

A Closer Look at Chlamydia 


A Closer Look at Chlamydia 

Chlamydia is widespread among the sexually active population, regardless of race, ethnicity, age, or gender. It is more concentrated among adolescents than any other STD with the highest rates seen among female adolescents. Data on male adolescents also reveal an alarming level of infection.


Forty percent of chlamydia cases are reported among young people, 15 to 19 years old. Reported prevalence among sexually active women is consistently more than five percent, with prevalence among teenage girls often exceeding 10 percent more than one in 10. And while the data are more limited for men, studies of adolescent males tested in high schools and other settings have found prevalence of more than five percent (Cohen, 1998; Ku, 1997). Recent studies and screening programs in multiple settings throughout the country come to the same conclusion: chlamydia continues to exact a devastating toll among our nation's young people.


Chlamydia is common among all races and ethnic groups, but prevalence is somewhat higher among racial and ethnic minorities, most likely due to the lack of access to screening and treatment programs.


Chlamydia prevalence remains higher in areas without longstanding screening and treatment programs. The highest rates are reported in the southern states. In 1999, seven out of the 10 states with the highest rates were located in the southern region of the United States. If the level of screening and treatment continues to increase, the disease will most likely decline in women across the nation.

This report is from the United States Department of Health and Human Services (US DHHS), Centers for Disease Control and Prevention (CDC), National Center for HIV, STD and TB Prevention (NCHSTP), web site (at and at as of July 6, 2004.
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This page last reviewed: Tuesday, July 21, 2015
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