Cases of HIV and syphilis among gay men in Bangkok are on the rise, according to data released by US and Thai health authorities on Friday.
Syphilis cases among gay men more than doubled from five percent in 2005 to 12.5 percent in 2011, said the report in the Centers for Disease Control and Prevention's Morbidity and Mortality Weekly Report.
Meanwhile, the annual prevalence of HIV also rose "significantly," from 24.5 percent in 2005 to 29.4 percent in 2011 among men who have sex with men (MSM), it said.
"These data show ongoing and increasing epidemics of HIV and syphilis infection among MSM in Bangkok," said the report.
The data came from the Silom Community Clinic, located in a central Bangkok hospital and near entertainment venues for gay men.
The clinic was founded in 2005 by a joint collaboration between the Thailand Ministry of Public Health and the US CDC, offering free and confidential tests in an environment "receptive to the health and concerns of the MSM community."
When the team first began collecting data about HIV infections in gay men in Bangkok in 2003, the HIV prevalence was 17 percent.
By 2005 the HIV prevalence in that group had risen to 28 percent, and now it is around 30 percent, said the report.
The data reported by the CDC on Friday was based only on patients who went to the Silom Community Clinic and requested a test for sexually transmitted infection (STI), and may not be representative of the wider gay population in Thailand, the study noted.
Researchers also cautioned that patients who seek out tests and retests tend to engage in higher levels of risky behavior such as anal sex without a condom, and so the findings may be skewed upward.
However, the data underscore "the urgent need for preventive interventions to reduce the spread of HIV and STI in this population," the study said.
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