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Hundreds of thousands of Americans may have chlamydia – and they don’t even know it.

According to a new government report, approximately 1.8 million people in the United States have the sexually transmitted disease, but only 1.4 million infections have been recorded, HealthDay News reported.  That equates to about 400,000 undiagnosed cases.

For their study, which was presented Tuesday at the STD Prevention Conference in Atlanta, researchers analyzed data from the 2007 to 2012 National Health and Nutrition Examination Survey.  Along with the revelation of underreported cases, they also found that young women are at a much greater risk of harboring chlamydia, with infection rates the highest among sexually active girls between the ages of 14 and 19.

Additionally, rates were much different between races; around 18.6 percent of sexually active black teens were found to have chlamydia compared to 3.2 percent of sexually active white teen girls.

Chlamydia is a sexually transmitted infection that can cause serious damage to a woman’s reproductive system, hindering her chances of getting pregnant later on in life.  Many people who have chlamydia may not exhibit symptoms until several weeks after having sex with an infected partner.  Symptoms can include abnormal discharge from the vagina or penis, a burning sensation during urination and pain or swelling in the testicles for men.

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