Syphilis guide: Etiology and epidemiology

On this page

• Etiology
• Epidemiology
• References

Etiology

Syphilis is a complex systemic disease caused by infection with the spirochete bacterium Treponema pallidum, subspecies pallidum.

Other non-venereal treponemal infections [bejel, yaws (certain African countries) and pinta (Central and South America)] are found in endemic countries.

Epidemiology

Infectious syphilis (primary, secondary and early latent stages) is the third most common nationally notifiable bacterial sexually transmitted infection (STI) in Canada.

The rate of infectious syphilis continues to increase in Canada, with rates increasing most rapidly among females. Between 2010 and 2019, female rates of syphilis had the highest increase when compared to chlamydia and gonorrhea. As rates are increasing in females, especially females of reproductive age (15-39 years old), rates of congenital syphilis increased as well^{Footnote 1}. Additionally, gay, bisexual and other men who have sex with men (gbMSM) are disproportionately affected. Higher rates are still reported in this population, although an increasing number of outbreaks in heterosexual populations have been reported in large urban centers as well as in more rural areas in Canada, since 2017^{Footnote 2}.

Congenital syphilis is re-emerging in Canada. Since congenital syphilis became reportable in Canada in 1993, the number of reported cases in Canada ranged from one to ten until 17 cases were reported in 2018, 53 in 2019 and 50 in 2020^{Footnote 1Footnote 3}.

More information

Local epidemiological information: Consult with your public health unit

National epidemiological information:

• Notifiable diseases online
• Infectious Syphilis and Congenital Syphilis in Canada, 2022 (infographic)^{Footnote 3}
• Report on sexually transmitted infections surveillances in Canada, 2019^{Footnote 1}
• Syphilis in Canada: Technical report on epidemiological trends, determinants and interventions^{Footnote 2}

Global epidemiological information: World Health Organization Report on global sexually transmitted infection surveillance

References