The study finds 26 percent of women age 14 to 19 infected with at least one of the most common sexually transmitted diseases such as human papillomavirus, chlamydia, herpes simplex virus and trichomoniasis.

The study, presented Tuesday at the National STD Prevention Conference in Chicago, is the first to examine the combined national prevalence of common STDs among adolescent women in the United States.

Study leader Dr. Sara Forhan also finds nearly half of the young African-American women are infected with an STD, compared to 20 percent of young white women.

Using data based on the 2003 to 2004 National Health and Nutrition Examination Survey, the study finds the two most common STDs overall are human papillomavirus at 18 percent and chlamydia at 4 percent.

The CDC (NASDAQ:HINA) recommends annual chlamydia screening for sexually active women under age 25 and that girls and women between the ages of 11 and 26 should be fully vaccinated against HPV.