About 1 in 4 teenage girls in the United States - and nearly half of black girls - has at least one sexually transmitted disease, according to a study released yesterday, providing the first national snapshot of infection rates among this age group.
Those numbers translate into an estimated 3.2 million adolescent females infected with one of the four most common STDs - many of whom may not even know they have a disease or that they are passing it to their sex partners.
"What we found is alarming," said Dr. Sara Forhan, a researcher with the Centers for Disease Control and Prevention and the study's lead author. "This means that far too many young women are at risk for the serious health effects of untreated STDs, including infertility and cervical cancer."
The study's authors analyzed data on 838 girls between ages 14 and 19 who participated in the 2003-04 National Health and Nutrition Examination Survey, an annual study that assesses a broad range of health issues. For the analysis, the teens were tested for human papillomavirus (HPV), chlamydia, trichomoniasis, and herpes. By far, the most common sexually transmitted disease was HPV. Of those infected, 15 percent had more than one STD.
"It shows that what people have always suspected is true," said Dr. Emily J. Erbelding, an infectious diseases specialist at Johns Hopkins Bayview Medical Center. "Sexually transmitted infections have been called a hidden epidemic because a lot of these conditions are going to be asymptomatic when they're diagnosed, but they're highly common."
The overall figures could be slightly higher because other sexually transmitted diseases - syphilis, HIV, and gonorrhea - were not included in the study, although epidemiologists say the prevalence is low for those infections among adolescents. The study did not include teenage boys.
The paper was being presented this week at a CDC conference on STD prevention in Chicago.
Forhan said she was surprised to see how readily the risk to young women appears. Of those in the study who said they had just one sexual partner in their lifetime, the prevalence of STDs was 20 percent, she said.
While parents may be surprised by the study, it's a reflection of what doctors have been seeing in their practices in recent years, said Dr. Ligia Peralta, chief of the Division of Adolescent and Young Adult Medicine at the University of Maryland Hospital for Children in Baltimore. In a small study done among girls in her university clinic in 2000, primarily black teens, 90 percent of the sexually active teens had HPV.
She called the CDC study "critical information for parents" and encouraged them to use this knowledge to be sure their daughters are being properly screened and taught about protection and prevention.
There are 19 million sexually transmitted diseases in the United States - costing the healthcare system $15 billion a year - and almost half occur among the 14-to-25 age group, said Dr. Kevin Fenton of the CDC. Officials called sexually transmitted diseases a public health epidemic and said efforts must be made to improve screening, education, and other prevention strategies for sexually active teens.