WASHINGTON — The overall incidence of syphilis has been dropping in the United States since the mid 1990s, but a syphilis epidemic is raging among men who have sex with men.
Several factors appear to be driving this syphilis epidemic, the most notable of which has been an increase in unprotected sex between men who are infected with HIV, Matthew Golden, M.D., said at the annual Interscience Conference on Antimicrobial Agents and Chemotherapy.
Based on data collected in Seattle and King County, Wash., men who are HIV positive are often having unprotected sex with other HIV-positive men. The rate of unprotected sex rose from 32% in 1994 to 45% in 2004. The percentage of HIV-positive men who have sex with men who said they had more than two sex partners in the preceding 2 months rose from 25% in 1993 to 39% in 2004.
These factors may help explain why the incidence of syphilis among HIV-positive men who have sex with men soared from about 55 cases/100,000 people in Seattle and King County in 1997 to a projected incidence of nearly 1,200/100,000 people in 2004, reported Dr. Golden, medical director for public health at the Seattle King County STD clinic.
“A 1%/yr rate is extraordinary,” compared with typical rates in the U.S. population, Dr. Golden said at the conference, sponsored by the American Society for Microbiology.
Although an education campaign about the risks of sexually transmitted diseases is being targeted to HIV-infected men in Seattle and King County, additional education programs appear needed, Dr. Golden added.
Other factors that may be helping to feed this syphilis epidemic include the recent growth in the availability and popularity of methamphetamine, and the growth of the Internet as a way for HIV-infected men to meet other HIV-infected men as potential sex partners. But the possible roles played by any of these factors remain speculative for the time being, Dr. Golden cautioned.