http://www.nytimes.com/2008/03/12/sc...hp&oref=slogin
The NY Times report is more specific:-
Nearly half the African-Americans in the study of teenagers ages 14 to 19 were infected with at least one of the diseases monitored in the study — human papillomavirus (HPV), chlamydia, genital herpes and trichomoniasis, a common parasite. The 50 percent figure compared with 20 percent of white teenagers, health officials and researchers said at a news conference at a scientific meeting in Chicago. The two most common sexually transmitted diseases, or S.T.D.’s, among all the participants tested were HPV, at 18 percent, and chlamydia, at 4 percent, according to the analysis, part of the National Health and Nutrition Examination Survey.
.... Although earlier annual surveys have tested for a single sexually transmitted disease in a specified population, this is the first time the national study has collected data on all the most common sexual diseases in adolescent women at the same time. It is also the first time the study measured human papillomavirus.
Dr. Douglas said that because the new survey was based on direct testing, it was more reliable than analyses derived from data that doctors and clinics sent to the diseases center through state and local health departments.