BOSTON (Reuters) - When a syphilis outbreak struck gay or bisexual men earlier this year, the County of Los Angeles Department of Health Services used Internet chat rooms to combat it.

The campaign used anonymous Internet chatroom participants to target educational messages directly to men at risk, Harlan Rotblatt reported at the annual conference of the American Public Health Association.

Researchers in San Francisco addressed a similar outbreak earlier this year by having "experts" educate individuals in chatrooms frequented by gay or bisexual men, but according to Rotblatt, the strength of the Los Angeles approach was in using people from the targeted community.

"If you come in as the authority, you are often discounted by the target audience," he told meeting attendees. "The idea was to see whether we could push this further if the message came from people who had established credibility as being part of the community, rather than representing the health department or so-called experts."

The outbreak came to the attention of the health department in March, when a cluster of 10 syphilis cases was identified through an early intervention program for people living with HIV. By November, a total of 125 cases had been documented.

"This was of particular concern because almost half of the MSM (men who have sex with men) and transgendered individuals involved were HIV-positive, and a third or more reported sex in public sex venues with multiple, anonymous partners," Rotblatt said.

In an interview with Reuters Health, Rotblatt noted, "We were a lot more accepted than we had thought. We anticipated problems that we didn't have.

The idea that the conversation was done organically, scripted very well, and that the chatters were fairly adept at picking up the flavor of a room, blending into that and responding in kind, contributed to the success."

He added, "We were concerned that it would look odd, like dropping a lead balloon into the conversation, but it wasn't taken that way."