Medical health officer Dr. Reka Gustafson of Vancouver Coastal Health said Thursday that 561 new syphilis cases were reported in British Columbia last year, and 86 per cent of them were among gay and bisexual men.
She said syphilis rates in 2012 across the Lower Mainland were already at their highest in 30 years, and the numbers climbed further in 2013.
Men who have more than one partner at the same time are at greater risk of becoming infected, Gustafson said.
The highest rates in Vancouver are among men between 30 and 49, though infections are increasing in all age groups.
She urged men who have sex with men to get tested every three to six months through blood tests available at doctors' offices, walk-in clinics, the B.C. Centre for Disease Control and other facilities.
Treatment involves antibiotics, especially penicillin.
"If you're a sexually active individual, especially a gay man in Vancouver, you're at risk for syphilis. The earlier you're diagnosed, the easier the treatment is and also the less likely you are to transmit to someone else. And the treatment is curative."
Syphilis is spread primarily by oral, vaginal or anal sex and if left untreated the disease can lead to blindness, hearing loss, brain damage and even death.
An infected person may not have any symptoms or initial ulcers or sores resembling bug bites on genitals and rashes on the palms and soles of the feet may disappear while the infection circulates through the body, Gustafson said.
"So awareness becomes really, really important. The initial symptoms, even if you have them, including the initial ulcers, can be painless."
Many factors are involved in the syphilis epidemic among gay and bisexual men but behaviour could be a key issue, Gustafson said.
"Our syphilis outbreak right now in Vancouver is affecting adult men, and a disproportionate rate are HIV-positive — about 69 per cent. Men who are HIV-positive typically have sex with other men who are similarly affected."
But the idea of preventing HIV transmission by having unprotected sex with someone of a similar HIV status may backfire when it comes to syphilis.
Gustafson said transmission doesn't necessarily involve intercourse because the disease can be passed on through oral sex or close skin-to-skin contact.
While rates of syphilis among men began to increase around 2003 and 2005, there was a dip in 2007 before a spike in 2010, she said.
Sometimes a temporary immunity to a sexually transmitted disease reduces rates before they rise again, Gustafson said, adding cities across Canada and elsewhere are struggling to deal with the issue.
"Practise safe sex, have fewer sexual partners and get tested and treated as soon as possible. Make sure all your partners are also tested and treated."
The latest Public Health Agency of Canada report in 2010 said that while reported syphilis rates across the country had declined overall, they started climbing sharply among men in 2001.
That report also cited the highest rates among men who have sex with men, as is the case in the United States and Europe.
"The causes for these increases are complex and include demographic shifts, as well as changing sexual attitudes and social contexts related to increased risky sexual behaviour," the report said.