It’s a scenario that happens, but no one knows precisely how often. It’s a Friday night, and two teens are getting frisky. A condom breaks, and panic ensues.

In that moment of alarm, teens in California and Washington, D.C., can turn to their cell phones for help–”via text messaging. “Txt 1 if ur condom broke. Txt 3 if s/he’s cheating on u. Txt 5 for STD info. Txt 6 if ur not sure uwant2have sex.”

Seconds later, there’s a response. If the condom broke, it says: “U may b at risk 4 STDs + pregnancy.” The message includes the name, telephone number and hours for a nearby clinic.

Each month, roughly 150 teens in San Francisco use this text message-based STD-prevention service. Of those, 40 percent text regarding broken condoms. The service is called SEXINFO.

Launched in 2006, it was developed in partnership with the San Francisco Department of Public Health and the Internet Sexuality Information Services to target African-American youth who are 15 to 19, a group considered high risk for gonorrhea and chlamydia.

Two years ago, SEXINFO was the only program of its kind in the United States. Similar programs have since developed in major metropolitan cities as advocates search for ways to spread HIV and AIDS prevention messages within the social networks of at-risk groups, such as teens.

People ages 13 to 29 accounted for 34 percent of HIV infections nationally, the largest percentage of any age group in 2006, according to the latest estimates available from the U.S. Department of Health and Human Services. That report calls HIV “an epidemic primarily of young people.”

In October, text messaging programs began in Los Angeles. In December 2007, the U.S. Centers for Disease Control and Prevention partnered with The Kaiser Family Foundation to launch KNOWIT, a national HIV-testing campaign where teens text their ZIP code to get the location of the closest testing centers. Two more text-based programs–”one for California statewide, and one in Toronto–” are expected to launch in spring 2009.

In Los Angeles, the new text message- based HIV-prevention program targets young gay and bisexual African-American and Latino men.

Unlike other programs, it’s not menubased, and relies less on public marketing.

Instead, led by a small group of teens, the program works to strengthen dialogue about health, wellness, relationships, homophobia and selfesteem within an at-risk group of 100 to 150 youths. It relies mainly on word of mouth, existing relationships and some outreach in clubs.

“It’s trying to reach a small group of young people to encourage dialogue,” said Pato Hebert of AIDS Project Los Angeles. “If you think it’s going to be plastered all over buses and billboards across the city for anyone to text, that’s not what our program is like. It’s a calculated experiment that we’re doing. It’s much more viral–”pun intended.”

Washington, D.C., adopted a texting program in 2008 called RealTalkDC. In its first month, the program saw 625 unique text messages sent to RealTalk. Neema Enriquez of Metro Teen AIDS, one of the partner organizations that launched RealTalk, said that the organization distributed surveys to one of every three people they tested. Thirty-five percent of those surveyed said they saw material for Metro Teen AIDS’s campaign.

Of those who were aware of the campaign, 76 percent said it impacted their decision to get an HIV test. “It’s hard to say whether that’s all because of texting, because we were also doing other initiatives at the same time trying to get people to get tested,” Enriquez said.

“Young people are also the least likely to use healthcare, so we’re trying to reach them in the ways they communicate,” said Michael Kharfen of the district’s department of health.

Advocates of the Los Angeles programs say their operational costs are low compared with many other initiatives, and, in the district, Kharfen estimated its program costs $25,000 annually.

“I don’t want to undersell the value of the resource, but it is something we certainly think is a very worthwhile investment,” he said.

Youth in Chicago have yet to see any such programs. A 2008 Chicago Department of Public Health report shows that for the first time since 2000, people under 30 were the leading age group of those diagnosed with HIV.

Although city officials have encouraged youth to use text messaging for other purposes, such as reporting violence in schools, the city has yet to employ that tactic for HIV and AIDS prevention and education.

“We have been in talks about it. It’s on the horizon,” said Maude Carroll of the AIDS Foundation of Chicago. “It’s great for reaching people who don’t have Internet access, and the technology is totally feasible, but we haven’t done it yet.”