Infectious syphilis and congenital syphilis in Canada, 2022

Rates between 2020 and 2022 occurred in the context of the COVID-19 pandemic, which included a period of decreased demand for and access to sexually transmitted and blood-borne infection (STBBI) services^{Footnote Ѱ}.

The COVID-19 pandemic reduced the demand for and access to services related to STBBIs, including prevention, testing, treatment, and other supportive services. This likely contributed to fewer reported cases of infectious and congenital syphilis between 2020 and 2022. As parts of the country experienced various levels of disruptions due to COVID-19 from 2020 to 2022, comparisons of reported infectious and congenital syphilis case counts and rates between the provinces and territories may also be inaccurate.

Infectious syphilis

In 2022, there were 13,953 cases of infectious syphilis^{Footnote **} reported nationally, for a rate of 36.1 cases per 100,000 population. The 2022 national rate of infectious syphilis was:

• 11% higher than the 2021 rate
• 109% higher than the 2018^{Footnote ┼} rate

The national reported rate of infectious syphilis remained relatively stable from 2016 to 2017, with a 5% increase. Substantial increases in the national reported rate of infectious syphilis were seen in subsequent years:

• From 2017 to 2018, an increase of 52%
• From 2018 to 2019, an increase of 42%
• From 2019 to 2020, a relatively stable rate, with an increase of 2%^{Footnote Ѱ}
• From 2020 to 2021, an increase of 9%^{Footnote Ѱ}

Trends by sex, sexual behaviour, and age

Nationally, 35% of cases reported in 2022 occurred among females, with a male-to-female ratio of 1.8, compared to a ratio of 3.8 in 2018. In 2018, 21% of cases occurred among females compared to 79% of cases among males.

• The national reported rate of infectious syphilis was 252% higher in females and 67% higher in males in 2022, compared to 2018.
• In 2022, national reported rates of infectious syphilis were highest in the 25 to 39-year age group for males and in the 20 to 29-year age group for females.

Cases reported among gay, bisexual and other men who have sex with men (gbMSM)^{Footnote §} represented 27% of all reported infectious syphilis cases in 2022.

• gbMSM represented 41% of total reported male cases in 2022, a 4% decrease from 2021 and a 25% decrease from 2018.
• The number of reported cases among gbMSM has remained relatively stable throughout time.

Social and structural determinants of health and health inequities play a role in the inequitable occurrence of syphilis across different populations^{Footnote ‡‡}.

Since 2018, reported rates of infectious syphilis have increased in almost all provinces and territories (except for Nova Scotia, Newfoundland and Labrador and Nunavut).

• In 2022, the highest number of reported infectious syphilis cases occurred in Ontario, followed by Alberta, Saskatchewan and Manitoba.
• The highest reported rates of infectious syphilis occurred in the Northwest Territories, followed by Saskatchewan, Manitoba and Nunavut.
• The highest rate increases since 2021 occurred in Nova Scotia and Yukon, with increases of 221% and 643%, respectively.
• Provinces and territories that had reported rates of infectious syphilis higher than the national rate of 36.1 cases per 100,000 population included:
  • Northwest Territories (363.3 cases per 100,000 population)
  • Saskatchewan (186.6 cases per 100,000 population)
  • Manitoba (136.4 cases per 100,000 population)
  • Yukon (121.8 cases per 100,000 population)
  • Nunavut (113.9 cases per 100,000 population)
  • Alberta (73.9 cases per 100,000 population)
• Provinces and territories that had reported rates of infectious syphilis lower than the national rate of 36.1 cases per 100,000 population included:
  • British Columbia (28.0 cases per 100,000 population)
  • Ontario (22.9 cases per 100,000 population)
  • Québec (14.1 cases per 100,000 population)
  • New Brunswick (4.9 cases per 100,000 population)
  • Nova Scotia (4.6 cases per 100,000 population)
  • Newfoundland and Labrador (2.7 cases per 100,000 population)
  • Prince Edward Island data not shown to reduce the risk of identifying individuals (DNS)

The shift in syphilis infections to the heterosexual population and particularly women is evident in the proportion of women affected across Canada in 2022:

• 40% or more reported cases are female in Alberta, Saskatchewan and Manitoba as well as in Yukon, the Northwest Territories and Nunavut. Particularly, in Saskatchewan and Manitoba, up to 53% to 55% of reported cases are female. Females represent 48% to 50% of the overall population in these (and 50% to 51% in all other) provinces and territories.

In 2022, the highest reported rates of infectious syphilis, nationally, occurred in 20 to 39-year olds. However, in Saskatchewan, Manitoba and the Northwest Territories, this age range drops lower to include 15 to 39-year olds.

• In Nunavut, where the reported rate of infectious syphilis is the fifth highest in the country (113.9 cases per 100,000 population), 70.2% of the population is under 40 years of age, and 30.9% are under 15 year of age. In the Prairie provinces and the three territories, which collectively have the highest reported rates of infectious syphilis in the country—higher than the national reported rate of 36.1 cases per 100,000 population—more than 50% of the population is under 40 years of age.

Syphilis screening and timely treatment are essential to prevent transmission and complications. Find Public Health Agency of Canada (PHAC)'s recently updated syphilis screening recommendations in the STBBI Guides for Health Professionals.

Congenital syphilis

There were 117 cases of confirmed early congenital syphilis^{Footnote **} reported in 2022, with a rate of 31.7 cases per 100,000 live births. The 2022 national rate of confirmed early congenital syphilis was:

• 7% higher than the 2021 rate
• 599% higher than the 2018^{Footnote ┼} rate

In 2022, there were 246 reported cases of congenital syphilis, which includes confirmed early congenital syphilis, probable early congenital syphilis, syphilitic stillbirth, and unknown-stage congenital syphilis.

Note that Canada does not currently have a national case definition for probable early congenital syphilis, syphilitic stillbirth, or unknown/unspecified-stage congenital syphilis. Data for these cases are submitted according to each province and territory’s own case definitions. Currently, only Alberta, Saskatchewan and Manitoba have case definitions for probable early congenital syphilis and syphilitic stillbirth. British Columbia and Québec have case definitions for both confirmed and probable early congenital syphilis that include stillbirths, while Yukon has a case definition for confirmed cases only of early congenital syphilis that includes stillbirths. In addition, the Northwest Territories have a case definition for syphilitic stillbirth, but not for probable early congenital syphilis.

From 2018 to 2022, reported rates of infectious syphilis among females aged 15 to 39 years increased annually.

• The 2022 national reported rate of infectious syphilis among females aged 15 to 39 years was 239% higher than the 2018 rate.
• National reported rates of confirmed early congenital syphilis are also steadily increasing in parallel with the increase in reported rates among females aged 15 to 39 years.

The highest number of confirmed early congenital syphilis cases reported in 2022 occurred in the Prairie provinces and Ontario, with the following reported rates of cases per 100,000 live births: Saskatchewan, 175.0; Manitoba, 122.7; Alberta, 69.3; and Ontario, 17.3.

The number of reported cases of confirmed early congenital syphilis has increased in most provinces and territories, including British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, Québec, New Brunswick and the Northwest Territories.