BOSTON -- Public health officials are using Facebook to educate teens about the rising spread of sexually transmitted infections, as nearly one in four young people admit to having multiple sexual partners.

The campaign mixes street outreach, the Internet, and traditional media and targets sexually active teens between the ages 15 and 19, who represent the highest percentage of new cases of Chlamydia and gonorrhea in Boston.

"This campaign breaks new ground for the city of Boston in our efforts to reach young people wherever they are -- be it on Facebook or watching BET,” said Mayor Thomas M. Menino. “We know that with awareness comes changes in behavior, and that's what we are trying to achieve.”

According the 2009 Health of Boston report, 56 percent of Boston Public High School students have had sex, including 40 percent of those younger than 16; 24 percent of sexually active BPS students had more than six partners. Only 71 percent of sexually active students had used a condom during their last sexual contact.

As part of the campaign, the Public Health Commission created a Facebook page, which chronicles campaign activities with YouTube videos. Fans of the page are allowed to anonymously post questions about sexual health that are answered by Boston Public Health Commission staff. They can also participate in opinion polls or get answers to frequently asked questions about sexually transmitted infections, or link to free STI testing sites in Boston.

“STIs are entirely preventable, and yet too many of our youths in Boston and across the country are getting infected,'' said Dr. Barbara Ferrer, executive director of the Boston Public Health Commission. “It is critically important that we create an environment where young people can start to have a conversation about the fact that this behavior is not OK."

That conversation started this spring with a student video contest called Get Reel: Check Yourself, which ran on YouTube and was sponsored by Menino and the Public Health Commission.

The winning video, created by Heidi Hillary Little, 16, and Anastasia Tatiana Walker, 15, was a comedy skit set in a makeshift classroom where a teacher, Ms. Tinkleberry, offers students instructions on how to avoid STIs. One student confuses STIs with the SAT, the college entrance exam, and winds up getting infected. The message of the one-minute video was that youths should use condoms to reduce their risk of contracting a sexually transmitted infection.

Out of that video came the campaign’s message: “A perfect score on the SATs might be hard, but preventing STIs isn’t. Do your homework. Protect yourself. Don’t get infected.”

In 2008, the incidence rate for chlamydia among 15- to 19-year-old females was 4,726 per 100,000, compared to 673 per 100,000 for women of other ages. In males ages 15-19, the incidence rate was 1,608 per 100,000.

"Clearly, we need to do a better job of educating teens about sexually transmitted infections,” Barry said. “The costs of staying silent are too high.”