Infectious and Congenital Syphilis in Canada, 2010-2015

Background: Syphilis is the third most commonly reported notifiable sexually transmitted infection (STI) in Canada, following chlamydia and gonorrhea, respectively. Rates of this STI have been rising rapidly in Canada since 2001.

Objective: To summarize trends observed in syphilis rates for 2010 to 2015 in Canada.

Methods: Laboratory-confirmed cases of infectious syphilis and early congenital syphilis were reported to the Public Health Agency of Canada by all of the Canadian provinces and territories. National infectious syphilis rates were computed, as were rates per sex, age group and province/territory. Rates of congenital syphilis were also calculated.

Results: From 2010 to 2015, the rate of infectious syphilis in Canada increased by 85.6%, from 5.0 to 9.3 cases per 100,000 population. In 2015, a total of 3,321 cases of infectious syphilis were reported, mainly in males (93.7%), among whom the rate was 17.5 cases per 100,000 males versus 1.2 per 100,000 females. The rate also rose faster among males in 2010-2015, a 90.2% increase versus 27.8% among females. Individuals aged 20-39 years had the highest rates. Across the provinces and territories, the highest rates of infectious syphilis were in Nunavut, British Columbia and Manitoba. The rate of congenital syphilis decreased from 2010 to 2014 (1.6 to 0.3 cases per 100,000 live births) before increasing to 1.5 cases per 100,000 live births in 2015, which corresponds to six reported cases.

Conclusion: Rates of syphilis continue to rise in Canada, especially among young men, and this is consistent with trends in the United States of America and European Union. Based on data from Canada and from these regions, the sexual behaviour of men who have sex with men (MSM) is thought to be a major risk factor for syphilis.