Can HIV Drugs Boost Syphilis Risk?

MONDAY, Jan. 16, 2017 -- Gay and bisexual men taking antiretroviral drugs to treat HIV infection may be at increased risk for syphilis, new research contends.

Based on a review of available evidence, the investigators concluded that the drugs may boost susceptibility to the bacterium that causes syphilis, although the study did not prove cause-and-effect.

The finding might explain why new and repeat cases of syphilis in gay and bisexual men have risen sharply compared to other sexually transmitted infections over the past decade, the researchers wrote.

The study team was led by Dr. Michael Rekart, from the University of British Columbia's School of Population and Public Health in Vancouver. The findings were published in the Jan. 16 issue of the journal Sexually Transmitted Infections.

The authors of an editorial that accompanied the study said the theory is "intriguing" and "warrants careful consideration." But the editorial also suggested that the increase in syphilis cases among gay and bisexual men may be due to other factors.

"We are living in an era where [antiretroviral therapy] is being used to effectively treat and prevent HIV infection. To some extent this seems to have tempered the urgency to control other [sexually transmitted infections]. As history has shown many times over, that would be a costly mistake," said Susan Tuddenham, Maunank Shah and Khalil Ghanem, from Johns Hopkins University School of Medicine in Baltimore.

"Over the past 15 years, syphilis rates among [gay and bisexual men] have been rising unabated," Tuddenham and colleagues noted in a journal news release.

"If further investigations support a role for [antiretroviral therapy] in increasing susceptibility to syphilis, this will provide one more reason why screening, diagnosis and treatment of [sexually transmitted infections] in [gay and bisexual men] must be prioritized," the editorial concluded.