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In 2020, the Public Health Agency of Canada (PHAC) published a report on syphilis that summarizes epidemiological trends, describes recent syphilis outbreaks and discusses proposed interventions and policies to support the control of syphilis.1 This article highlights key parts of this report relevant to frontline service providers in Canada.

Overview of syphilis

Syphilis is a bacterial infection that is primarily transmitted through vaginal, anal or oral sex. It can also be passed from a parent to a baby during pregnancy or childbirth (called congenital syphilis).

If syphilis is left untreated, it can progress through four stages:

  • Primary stage (usually three or more weeks after infection): A person may have a sore at the site of infection and/or the nearby lymph nodes might be swollen.
  • Secondary stage (usually two to 12 weeks after the primary stage begins): A person may get a rash, have mild flu-like symptoms, have wart-like lesions or have other symptoms (e.g., blurred vision, hearing loss).
  • Latent stage: The person has no symptoms. The latent stage can last many years. The first year is referred to as the early latent stage, and during this time a person is infectious. After the first year, the disease progresses to late latent syphilis, and the person is no longer infectious.
  • Tertiary stage (usually within 15 years after infection): It is rare for latent syphilis to progress to tertiary syphilis. If a person does progress to this stage, they may start to experience more severe health consequences such as problems with the brain, heart and other organs. In rare cases, untreated syphilis can be life threatening at the tertiary stage.

At any stage of infection, a person can experience neurosyphilis. This happens when syphilis spreads to the nervous system. Many people who have neurosyphilis do not experience symptoms. For those who experience symptoms, they can include problems related to the brain such as meningitis, and problems with vision or hearing.

Congenital syphilis is when syphilis is passed to a baby during pregnancy or childbirth. It can cause miscarriage, stillbirth, neonatal death or debilitating symptoms and abnormalities that may be present at birth or show up later. If syphilis is treated early in pregnancy the chance of congenital syphilis is dramatically reduced.

A person is only infectious (meaning they can pass syphilis to others) if they are in the primary stage, the secondary stage or the early latent stage.

The most common test for syphilis is a blood test. However, if a person presents with a sore, the sore can be swabbed to test for syphilis.

Syphilis is usually easily treated with penicillin. However, treatment can be more complicated for people who are diagnosed late in their infection or for those who are allergic to penicillin.

Congenital syphilis and factors that contribute to risk

The number of cases of congenital syphilis has been rising sharply in recent years. In 2018, there were 17 cases of congenital syphilis reported in Canada. This was the first time in several decades that more than 10 cases were reported in one year. Even more concerning is that new data released since the publication of the PHAC report show that there were 45 cases of congenital syphilis in 20192 and 73 cases in 2020.3

There is limited evidence on the determinants and risk factors associated with maternal and congenital syphilis in Canada. According to this limited evidence, access to appropriate prenatal care, being younger than 20 years of age or older than 30 years of age and using substances are the most commonly reported risk factors of maternal and congenital syphilis. The literature suggests having a lower income, residing in a rural or remote location and having experienced stigma and discrimination or historical trauma are all underlying social and structural determinants.

The most important way to prevent congenital syphilis is to support access to appropriate prenatal care. This includes both screening and treatment for syphilis. PHAC’s testing guidelines for sexually transmitted and blood-borne infections (STBBI) recommend screening all pregnant people for syphilis in the first trimester of their pregnancy or at their first prenatal visit. Guidelines also recommend that re-screening each trimester should be considered for people at risk for syphilis, and in regions where there is an outbreak of syphilis in heterosexual populations. People who experience a stillbirth should be tested for syphilis as well.

Increasing access to quality pregnancy care and syphilis testing is critical for preventing congenital syphilis. Access can be improved through initiatives such as testing pregnant women when they present to hospital emergency departments. Interventions are also needed to address the systemic barriers that prevent people from accessing care, including racism, stigma and discrimination.

Epidemiological trends in syphilis

Canadian data are available for infectious syphilis only, because late-stage syphilis is not reportable in some provinces.

National trends

Syphilis has been a reportable infection in Canada since 1924. The rate of infectious syphilis was very high in the 1940s and started to decline steadily after that period. It continued to decline in the 1980s and was very low by the mid-1990s. However, the rate began to climb again in the early 2000s and has risen dramatically in recent years. The graph below shows the rate of infectious syphilis per 100,000 people reported per year over 20 years (from 1999 to 2018) (Graph 1).

The reasons for this dramatic increase are not fully known, but some factors probably contributed to this rise. The rise in syphilis cases coincides with the introduction of highly effective HIV treatment in the late 1990s, which may have contributed to a decrease in condom use. Since the early 2000s, dating apps have become more popular, which facilitates meeting more potential sexual partners. The increase in syphilis also coincides with an increase in the use of drugs while having sex, called party and play (PnP).

Provincial and territorial trends

While almost all provinces and territories have seen an increase in the rate of syphilis in recent years, some areas of Canada have been affected much more than others. In 2018, the overall rate of syphilis infection in Canada was 17.1 per 100,000 people. Nunavut, Manitoba, the Northwest Territories and Alberta all had rates of syphilis above the national average. Data released since the publication of the PHAC report show that in 2019, the overall rate in Canada was 21.4 per 100,000 people and that the Northwest Territories, Nunavut, Alberta, Manitoba and Saskatchewan had rates higher than the national average.2 Table 1 shows the rate for each province and territory, in 2018 and 2019.

Table 1. Rate of syphilis per 100,000 people by province or territory in 2018 and 2019

Province or territory

Rate per 100,000 people in 2018

Rate per 100,000 people in 2019

British Columbia


















New Brunswick



Prince Edward Island



Nova Scotia



Newfoundland and Labrador






Northwest Territories






Since 2017, most provinces and territories have declared a syphilis outbreak, either in a particular region or across the whole jurisdiction. Outbreaks have been declared in British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, Quebec, Northwest Territories, Nunavut and Nova Scotia.


Demographic characteristics


Between 1991 and 2000, males and females had similar rates of syphilis. Since 2002, males have had significantly higher rates of syphilis than females. In 2018, the rate among males was 27.1 per 100,000 people and in females it was 7 per 100,000 people. The increase in reported cases among males was driven mainly by cases among gay, bisexual and other men who have sex with men (gbMSM).

While much lower than the rate among males, the number of infections among females has grown sharply in recent years. The infection rate in 2018 nearly tripled from the rate in 2017 (2.4 per 100,000 people in 2017 to 7.0 per 100,000 people in 2018). The most dramatic increases among females have been in Alberta and Manitoba, which have both reported outbreaks among heterosexual populations. Between 2014 and 2018, the rate of infection among females in Canada overall increased by 204%. In comparison, the rate among females increased by 416% in Alberta and by 240% in Manitoba.


The rate of syphilis diagnosis has risen among every age group in recent years, except for people aged 15 years and under. In 2018, the rate was highest among people aged 25 to 29 years (45.4 per 100,000 people), closely followed by those aged 30 to 39 years (37.7 per 100,000 people). Among females, the largest increases from 2017 to 2018 were among females of child-bearing age (15 to 39 years), with those aged 20 to 24 years having the highest rate of syphilis in 2018 (26.4 cases per 100,000 people). This has contributed to the increase in cases of congenital syphilis. Among males, the increase in cases is more evenly distributed across age groups, with the highest rate in 2018 reported among males aged 25 to 29 years (65.1 per 100,000 people).

What factors contribute to a person’s risk of contracting syphilis?

There are many factors that have been found to be associated with a greater likelihood of acquiring syphilis. These include both underlying determinants and proximate determinants. Underlying determinants do not put a person directly at risk for syphilis but shape the conditions of people’s lives and their access to resources, which influence vulnerability to syphilis. Proximate determinants are factors that directly increase risk of syphilis.

Underlying determinants

While not all of these underlying determinants have a large amount of evidence to support their influence, there is at least limited data to support these findings.

Underlying determinants fall into five broad categories.

Demographic characteristics: Being male, of younger age and experiencing ongoing colonialism and structural disenfranchisement as an Indigenous person are associated with an increased risk for syphilis.

Socioeconomic factors: Having a low income and not having secure housing are associated with an increased risk for syphilis.

Physical environments: Living in certain provinces and territories (some regions are more heavily affected than others), living in urban centres rather than rural areas and having a history of incarceration are associated with an increased risk for syphilis.

Social norms and sexuality: Changes in sexual behaviours and sexual culture are associated with an increased risk for syphilis. Hormonal contraceptives and dating apps are examples of ways in which sexual behaviours and cultures have changed.

Health systems, policies and guidelines: The ways in which STBBI screening guidelines have been implemented or changed over time and educational gaps in sexual health curriculums regarding sexually transmitted infection (STI) risk factors and transmission methods have been found to be associated with an increased risk for syphilis.

Proximate determinants

There are a variety of proximate determinants that directly increase the risk of syphilis at the individual level. Proximate determinants fall into four broad categories.

Violence, discrimination and stigmaPeople who experience violence, discrimination and stigma have a higher risk of acquiring a syphilis infection. For example, people who experience intimate partner violence have an increased risk of contracting syphilis because it can be difficult or impossible to negotiate condom use in this situation. Also, experiences of discrimination and stigma in healthcare settings due to race, sexual orientation, gender identity or substance use affect an individual’s ability to access appropriate STI testing, treatment and care.

Mental health and substance use issuesMental health issues such as anxiety and depression have been associated with an increased likelihood of acquiring syphilis. This may be because mental health issues can make it difficult for people to advocate for condom use. Alcohol and drug use (both injection and non-injection) have also been shown to be associated with an increased risk of acquiring a syphilis infection. More research is needed to know whether syphilis is being transmitted because of riskier sexual behaviours among people who use drugs or if syphilis may be being transmitted through the sharing of drug use equipment. Among gbMSM, syphilis is often associated with the use of crystal meth and other stimulants when having sex (PnP). PnP often involves condomless sex, multiple sex partners and anonymous sex partners.

Sexual behaviours: People who have condomless sex are much more likely to acquire syphilis than those who consistently use condoms. Also, risk of syphilis transmission increases with the number of sex partners that a person has. In particular, gbMSM may be at increased risk of syphilis because there is a higher prevalence of multiple sex partners and condomless sex in this population, although these factors are relevant in both males and females. People who attend public sex venues such as bathhouses and cruising spots may be at increased risk because these venues are associated with inconsistent condom use and a higher number of sexual partners. While transactional sex (exchanging sex for money or other gifts/services) has historically been shown to be associated with greater syphilis risk, it does not appear to be behind the latest increases in cases.

Clinical factorsHIV and syphilis co-infection is common because both of these infections are transmitted sexually. Also, a syphilis infection makes it easier for HIV to be transmitted and vice versa. Syphilis may progress more quickly and become more difficult to treat in people who are living with HIV than in those who are not. Co-infection with syphilis and another STI, such as chlamydia, is also common.

There is some concern that use of pre-exposure prophylaxis (PrEP) may increase the risk for syphilis because of lower condom use; however, there is limited evidence to support this view.

Interventions to address syphilis for frontline service providers

There are many interventions to facilitate the prevention, detection and treatment of syphilis. Service providers working in HIV and hepatitis C can play a role in helping to address the recent rise in syphilis cases as syphilis disproportionately affects some of the populations they serve.

Primary prevention

Condoms are effective at reducing the risk of syphilis transmission, although they do not eliminate the risk. Service providers can encourage condom use through initiatives to distribute condoms and through education about condoms and healthy sexual relationships.

For healthcare providers who may not feel comfortable talking to clients about syphilis or who lack knowledge about syphilis and how it is prevented, the Public Health Agency of Canada offers tools to help them learn about syphilis and to guide them on how to talk to clients.4 It is important that healthcare providers are comfortable talking about syphilis with people of all genders and sexual orientations in a way that is not stigmatizing. It is also important that people have access to healthcare that is trauma informed and culturally adapted.

There are many factors in a person’s life that can lead to poor health outcomes including an increased risk of contracting syphilis. Interventions that help to address the social determinants of health, such as providing safe and secure housing, can indirectly help to prevent syphilis.

There is currently no approved vaccine for syphilis, but scientists are working to develop one. Another possible strategy to prevent syphilis is for people at ongoing risk to take a medication called doxycycline to reduce their chance of acquiring syphilis. Research studies are underway to determine the effectiveness of this approach.


Regular testing is important for people who may be at risk for syphilis. There are several approaches that can help to increase the uptake of syphilis testing.

Integrating syphilis screening into routine testing for other STBBIs whenever possible can help to increase uptake. Also, because HIV and syphilis co-infection is common, it is recommended that syphilis testing should be a routine part of HIV care.

For people who are at ongoing risk for syphilis, frequent testing can help to detect a syphilis infection early. Studies done in Canada, the United States and Australia suggest that testing gbMSM for syphilis every three months helps to catch infections early and helps prevent onward transmissions. It may be helpful for people to receive automatic reminders to let them know when they should test again.

While most people choose to access testing through a sexual health clinic or their primary care provider, offering testing in other settings can help to reach more people. Some alternative settings where testing can be done include community spaces, saunas/bathhouses and commercial sex venues, community events and festivals, hospital emergency departments and correctional facilities.

The time it takes to get a test and the inconvenience of going to a testing clinic can be barriers for some people. Processes that aim to make testing more convenient are sometimes called “express testing.” Examples of express testing include offering walk-in testing and shortening the time it takes to get a test by allowing clients to forgo the physical examination and skip to blood sample collection. Models for testing with an online component can also help to make testing more convenient, by reducing the number of times that a person needs to come into a clinic. There is some evidence that providing incentives for people to get tested (such as a gift card) can help to encourage people to get tested. Dried blood spot testing can help to reduce barriers because the sample does not need to be collected by a healthcare provider. Point of care testing is another promising option, but no point of care test for syphilis has been approved for use in Canada yet.

Case management

There are a few initiatives that can help to support people who are diagnosed with syphilis to identify and notify their past sexual partners and to access treatment.

Partner notification is a helpful tool for reaching people who may have been exposed to syphilis. With partner notification, a person who has tested positive for syphilis tells their past sexual partners of their diagnosis, or alternatively a healthcare or public health professional can contact them to let them know they may have been exposed to syphilis. The healthcare professional does not disclose the person’s name.

Some people are reluctant to provide the names of their sexual partners,  because of fears of being stigmatized or of emotional or physical consequences from partners, or because they may have been a victim of sexual assault. Another challenge to contact tracing is that some people may not know the names and phone numbers of one or more of their sexual partners (for example, sexual partners with whom they communicated only through a dating app). In cases like this, it may be possible to do Internet-based notification (e.g., through social networking sites, anonymous email).

Beyond standard contact tracing, it can be useful to contact people in a person’s social network more broadly than just their sexual contacts. This is called cluster notification. With this strategy, the individual identifies people in their social network who may benefit from testing. This approach may be particularly useful in areas where there is a syphilis outbreak.

In terms of treatment, it is important that people who test positive for syphilis, as well as their sexual partners, are treated as soon as possible. This benefits their own health and reduces the chance of passing syphilis to others. People who have more advanced disease, people who are pregnant, newborns and people who receive an antibiotic other than penicillin require repeated dosing and close follow-up to make sure their treatment was successful.

Related resources

Syphilis – CATIE Fact Sheet

2019 Canadian Guidelines for Sexual Health Education - Sex Information and Education Council of Canada

Canadian Guidelines on Sexually Transmitted Infections – Public Health Agency of Canada


  1. Public Health Agency of Canada. Syphilis in Canada, technical report on epidemiological trends, determinants and Interventions. Centre for Communicable Diseases and Infection Control, Infectious Disease Prevention and Control Branch, Public Health Agency of Canada; 2020. Available from: https://www.canada.ca/en/services/health/publications/diseases-conditions/syphilis-epidemiological-report.html
  2. Public Health Agency of Canada. Infectious syphilis in Canada 2019 – Canada Communicable Disease Report. Centre for Communicable Diseases and Infection Control, Infectious Disease Prevention and Control Branch, Public Health Agency of Canada; 2020. Available from: https://www.canada.ca/en/public-health/services/reports-publications/canada-communicable-disease-report-ccdr/monthly-issue/2020-46/issue-10-october-1-2020/infectious-syphilis-2019.html
  3. Public Health Agency of Canada. Infectious syphilis and congenital syphilis in Canada, 2020 (infographic). Centre for Communicable Diseases and Infection Control, Infectious Disease Prevention and Control Branch, Public Health Agency of Canada; 2021. Available from: https://www.canada.ca/en/public-health/services/publications/diseases-conditions/infectious-syphilis-congenital-syphilis-canada-2020.html
  4. Public Health Agency of Canada. Section 2: Canadian guidelines on sexually transmitted infections – primary care and sexually transmitted infections. Public Health Agency of Canada; 2013. Available from: https://www.canada.ca/en/public-health/services/infectious-diseases/sexual-health-sexually-transmitted-infections/canadian-guidelines/sexually-transmitted-infections/canadian-guidelines-sexually-transmitted-infections-17.html

About the author(s)

Mallory Harrigan is CATIE's knowledge specialist in HIV testing. She has a masters degree in community psychology.