STDs take a terrible toll on teenagers. Chlamydia is the most common and causes the most damage to teenage girls. A bacterial infection which can be easily treated if diagnosed, can cause internal scarring and lead to infertility. The younger the girl is, the more vulnerable her cervix is to infection. No one knows yet whether the damage that this STD causes to girls can also affect boys, but it can cause a pretty painful swelling of the testes. With no symptoms, kids pass this back and forth to each other.

Internal scarring in girls, resulting in infertility, sometimes is undiagnosed until the grown woman seeks infertility treatments. After months or years, undiagnosed chlamydia can lead to pelvic inflammatory disease. Most teens are unaware of how common STDs are and few can even name chlamydia, as the most common or even as an STD.

A recent press release from the Kaiser Family Foundation stated that although one in four Americans will get an STD, very few believe that they are at risk. So, a very big gap exists between the way things are and the way people think they are. According to this report, only 34 percent of women and 22 percent of men named chlamydia when asked to name STDs of which they have heard. Even though one out of four Americans will get an STD, the overwhelming majority, as high as 74 percent in the men's sample, think the odds are only one in ten.

"There's a yawning gap between theory and practice on STDs: young men and women are talking the talk, but they are not walking the walk in terms of condom use, STD conversations, and getting tested," says Cynthia Leive, Senior Editor, News and Features, Glamour.