Rates of chlamydia, gonorrhea and syphilis remain at high levels in the United States—particularly among teens—according to new data from the Centers for Disease Control and Prevention (CDC), reported on by Reuters. All three of these sexually transmitted infections (STIs) increase the risk of HIV transmission.

“Chlamydia and gonorrhea are stable at unacceptably high levels, and syphilis is resurgent after almost being eliminated,” said John Douglas, director of the division of sexually transmitted diseases at the CDC. “We have among the highest rates of [STIs] of any developed country in the world.”

Among other data, the CDC study also found that 1.2 million chlamydia cases were reported in 2008, up from 1.1 million in 2007. In addition, adolescent girls ages 15 to 19 had the most chlamydia and gonorrhea cases of any age group at 409,431. Blacks, while representing only 12 percent of the U.S. population, accounted for almost 71 percent of reported gonorrhea cases and nearly half of all chlamydia and syphilis cases in 2008. And 63 percent of syphilis cases were reported among men who have sex with men.

Douglas said that more comprehensive sex education for children and teens is necessary to promote knowledge about using condoms, limiting the number of sex partners and avoiding sex with people who have many other sex partners.

“We haven't been promoting the full battery of messages,” Douglas said. “We have been sending people out with one seat belt in the whole car.”