Concerning Rise in Syphilis Cases in Canada

Often associated with history books or period novels, syphilis: Often associated with history books or period novels, syphilis is far from being a relic of the past. In Canada, it remains very present, and has seen a sharp increase in recent years. According to data from the Public Health Agency of Canada, the number of infectious syphilis cases nearly doubled between 2018 and 2023, rising from 6 371 to 12 135 cases.¹.

Understanding syphilis and its symptoms is an important step toward protecting your sexual health and reducing the risk of STIs.

What Exactly Is Syphilis?

Syphilis is a sexually and blood-transmissible infection (STI) caused by a bacterium called Treponema pallidum.

Nicknamed “the great imitator,” syphilis lives up to its name: its symptoms can resemble those of many other infections or even go completely unnoticed, making diagnosis challenging. Knowing how it manifests is essential for early detection and protecting your sexual health.

How Is It Transmitted?

Infectious syphilis is mainly transmitted through direct contact with a chancre, a sore or ulcer on the skin or mucous membrane. This usually occurs during sexual activity, including:

• Vaginal or frontal sex;
• Anal sex;
• Oral sex (including oral-anal contact or anulingus).

It can also spread through sharing sex toys or drug injection equipment, though these routes are less common.

Even if a person with syphilis has no symptoms, they can still spread the infection.

Syphilis can also pass from a pregnant person to their baby during pregnancy, causing congenital syphilis—a serious condition that can lead to severe complications for the child.

Symptoms of Syphilis

Syphilis can easily go unnoticed, especially in its early stages, as many people show no visible symptoms. When left untreated, it often progresses through different clinical stages,some highly infectious and others associated with late complications. There are three main categories: early syphilis (infectious period), late syphilis and neurosyphilis, which can occur at any stage.

Early Syphilis – Infectious Period

(usually within the first year after infection)

• Primary Syphilis (10 to 90 days after infection): A painless sore (chancre) at the site of infection (genital, anal, or oral), sometimes accompanied by swollen lymph nodes. The sore may heal on its own.
• Secondary Syphilis (a few weeks to a few months after infection): Widespread skin rash (often on the palms and soles), mucocutaneous lesions, flu-like symptoms, and swollen lymph nodes.
• Early Latent Syphilis (less than one year): No symptoms, but secondary symptoms may recur. The infection remains transmissible.

Late Syphilis

(infection lasting more than one year)

• Late Latent Syphilis or of Unknown Duration : No symptoms, with a low risk of transmission.
• Tertiary Syphilis: (5 to 40 years after infection): Cardiovascular complications, destructive lesions of the skin or bones, and neurological damage.

Neurosyphilis

Neurosyphilis can develop at any stage of infection and affect the brain or nervous system, causing vision or hearing problems, cognitive impairment, paralysis, or meningitis.

Il est important de noter qu’une infection à syphilis peut augmenter le risque d’être infecté·e et de transmettre le HIV.

Syphilis Cases Are Increasing: What the Latest Data Shows

In Canada, syphilis is experiencing a significant increase. According to a report from the Public Health Agency of Canada², the number of infectious syphilis cases nearly doubled between 2018 and 2023, highlighting the importance of screening and prevention.

Key Facts: Canada, 2023

• Men still account for the majority of reported cases, representing 64% of infections
• Among men, those aged 30 to 39 have the highest incidence rate
• Since 2018, the incidence rate among women has tripled.
• Among women, those aged 20 to 29 are most affected, making up 40% of female cases.
• The increase in cases is much faster in the non-GBMSM population (gay, bisexual, and other men who have sex with men), with a 177% rise compared to 2% in the GBMSM population

Alarming Increase in Québec City

The rise in syphilis cases isn’t limited to the national level: Québec City is feeling the impact particularly strongly.

According to the Public Health Directorate of the CIUSSS de la Capitale-Nationale, the incidence rate in 2025 has reached 21.4 cases per 100,000 residents, placing the region third in the province and well above the Québec average of 13.0 cases per 100,000.³.

The CIUSSS Public Health Directorate warns: 2025 could set a new record for reported cases.

Why Syphilis Is Making a Comeback: Prevention Challenges

Several factors explain why syphilis is sharply increasing in Canada:

• Insufficient Testing : Some infected individuals don’t get tested, especially if they have no visible symptoms (remember, syphilis can remain silent for a long time!).
• Limited Awareness: Gaps in sex education and STI prevention make it harder for people to recognize risks and take protective measures.
• Access to Care: Regional and socio-economic inequalities limit access to healthcare services, particularly among marginalized populations.
• Reinfection: Even after treatment, it’s entirely possible to contract syphilis again if exposed.

Syphilis Screening: What You Need to Know

Like most STIs, syphilis can go unnoticed. That’s why regular testing is recommended, even when you feel fine and have no symptoms.

Chez Prelib, le STI testing de la syphilis se fait par une prise de sang.

It’s important to consider the window period when testing for STIs, AKA the time after exposure during which an infection may be present but not yet detectable. A follow-up test at the end of the window period is recommended to confirm previous results. For syphilis, this period can last up to 12 weeks.

If you develop symptoms (such as a sore or chancre), an in-person consultation is advised, as a physical examination is essential for proper care.

How Syphilis Is Treated

Syphilis is treated with antibiotics, most often in injectable form. In most cases, a single injection is enough, but some situations may require a longer course of treatment. Regular clinical and serological follow-up is essential to monitor the response to treatment and correctly interpret subsequent test results.

Le traitement est offert gratuitement à la personne infectée et à ses partenaires, dans le cadre du Programme de gratuité des médicaments pour le traitement des infections transmissibles sexuellement.

Protecting Yourself From Syphilis Reinfection

Even after completing treatment, it’s possible to contract syphilis again if you’re exposed to the infection.

To reduce the risk of reinfection and transmission, it’s important to notify any sexual partners who may have been exposed. The look-back period for partner notification depends on the stage of the infection. This table outlines the recommended time frame for each stage to identify partners who should be informed.

Syphilis Prevention Strategies

In today’s context, prevention plays a crucial role in slowing the rise of syphilis cases. The most effective protection remains condom use, regardless of the type of sexual activity. Since it’s possible to be infected without knowing, routine testing is recommended for all sexually active single individuals—especially when new partners are involved or in cases of unprotected sex.

In addition to these measures, there is an extra prevention tool for certain at-risk individuals: doxy-PPE (Doxycycline Post-Exposure Prophylaxis). When taken within 72 hours after a high-risk exposure, doxy-PPE can reduce syphilis transmission by up to 70%⁴.

1. L’Agence de la santé publique du Canada (2025, février). https://www.canada.ca/fr/services/sante/campagnes/syphilis.html ↩︎
2. L’Agence de la santé publique du Canada (2025, février). https://www.canada.ca/fr/sante-publique/services/rapports-publications/releve-maladies-transmissibles-canada-rmtc/numero-mensuel/2025-51/numero-2-3-fevrier-mars-2025/syphilis-infectieuse-congenitale-2023.html ↩︎
3. Centre intégré universitaire de santé et de services sociaux de la Capitale-Nationale (2025, novembre). https://www.ciusss-capitalenationale.gouv.qc.ca/actualites/Hausse-syphili-infectieuse ↩︎
4. Institut national de santé publique du Québec (2025, mars). https://www.inspq.qc.ca/espace-itss/doxycycline ↩︎