Syphilis Blood Test: Results Guide for Canadians (2025)

A syphilis blood test is one of the most important tools doctors use to detect and monitor syphilis, a serious bacterial infection spread mainly through sexual contact. In Canada, syphilis rates have been climbing steadily in recent years, making routine testing more critical than ever for protecting your health and the health of your partners.

How Does a Syphilis Blood Test Work?

Syphilis testing in Canada typically involves a simple blood draw that checks for antibodies produced by your immune system in response to the Treponema pallidum bacterium. Whether you are experiencing symptoms, have had a known exposure, or are pregnant, understanding how this test works and what the results mean can help you take the right next steps. This article covers the test process, how to read your results, and when you should speak with your family doctor or visit a walk-in clinic.

What Is Syphilis?

Stages of Syphilis: What to Expect and When to Get a Syphilis Blood Test

Stage	Key Characteristics	Common Symptoms	Recommended Management
Primary Syphilis	Occurs 10–90 days after exposure; highly infectious	One or more painless sores (chancres) on genitals, anus, or mouth; swollen lymph nodes	Syphilis blood test (RPR or VDRL); single dose of benzathine penicillin G; notify sexual partners
Secondary Syphilis	Develops weeks to months after primary stage; bacteria spread throughout the body	Non-itchy rash on palms and soles, flu-like symptoms, mucous membrane lesions, hair loss	Syphilis blood test confirmation; benzathine penicillin G; partner notification and testing
Latent Syphilis	No visible symptoms; early latent (under 1 year) vs. late latent (over 1 year); still detectable by testing	No symptoms; infection remains in the body and can be transmitted during early latent phase	Routine syphilis blood test screening; penicillin treatment (dosage depends on latency duration); ongoing monitoring
Tertiary Syphilis	Occurs years to decades after initial infection; affects major organ systems	Gummas (soft tissue growths), cardiovascular complications, neurological damage (neurosyphilis)	Specialist referral; intravenous penicillin G for neurosyphilis; regular follow-up blood tests to monitor response
Congenital Syphilis	Transmitted from mother to baby during pregnancy or childbirth; a growing concern in Canada	Stillbirth, premature birth, bone deformities, rash, jaundice, anemia, developmental delays	Mandatory syphilis blood test screening during pregnancy; prompt penicillin treatment of infected mothers; newborn evaluation and treatment

Syphilis is a contagious infection caused by the bacterium Treponema pallidum. It spreads through vaginal, oral, and anal sexual contact. It can also pass from a pregnant person to their unborn baby, which is called congenital syphilis.

What makes syphilis tricky is that it progresses through stages. Each stage has different symptoms, and some stages have no symptoms at all. Without treatment, the infection can cause serious, long-term health problems.

According to Health Canada, syphilis is a reportable infection, meaning healthcare providers must notify public health when a case is confirmed. Early testing and treatment are key to stopping its spread.

The Four Stages of Syphilis

Understanding the stages of syphilis helps explain why a syphilis blood test may be recommended even when you feel fine. The infection behaves differently at each stage.

Primary Syphilis

About three weeks after exposure, one or more small sores called chancres appear. These sores are usually painless and often appear on the genitals, where they can be hard to notice. The sores heal on their own within four to six weeks, even without treatment. However, healing does not mean the infection is gone.

Secondary Syphilis

One to five weeks after the sores heal, a new set of symptoms can appear. These include a reddish-brown rash that may cover the entire body, including the palms of the hands and soles of the feet. Moist sores called condyloma lata may also develop on mucous membranes. These symptoms also clear up on their own, which can give a false sense of recovery.

Latent Syphilis

After secondary symptoms fade, the infection enters a latent (hidden) stage. During the early latent phase, which lasts less than one year, there are no symptoms but the infection can still flare up. In late latent syphilis, the person usually has no symptoms and is no longer contagious through sexual contact. However, a pregnant person can still pass the infection to their baby for up to four years after the initial infection.

Tertiary Syphilis

If left untreated for three to fifteen years, syphilis can reach its most serious stage. Tertiary syphilis affects multiple body systems and can cause:

• Gummatous syphilis — soft, tumour-like growths on the skin, bones, muscles, or organs, occurring in about 15% of untreated cases
• Cardiovascular syphilis — inflammation of the aorta, affecting about 10% of untreated cases
• Neurosyphilis — affecting the brain and nervous system, causing meningitis, dementia, paralysis, or stroke-like events in about 6.5% of untreated cases

Congenital Syphilis

When syphilis passes from a parent to a baby during pregnancy or childbirth, it is called congenital syphilis. Unlike the adult form, congenital syphilis does not have a primary stage. Instead, it can cause a range of serious problems in newborns and infants, including:

• Nasal discharge and congestion
• Skin sores or rashes
• Enlarged liver and spleen
• Eye inflammation (keratitis)
• Perforation of the hard palate
• Bone and joint abnormalities
• Vision loss

This is why screening for syphilis is a routine part of prenatal care in Canada. If you are pregnant, your provincial health plan typically covers syphilis testing as part of your regular prenatal blood work.

How Does a Syphilis Blood Test Work?

A syphilis blood test detects antibodies your immune system produces in response to the infection. There are two main types of antibodies that labs look for, and each requires a different type of test.

Non-Treponemal Tests: VDRL and RPR

The VDRL (Venereal Disease Research Laboratory) and RPR (Rapid Plasma Reagin) tests detect non-specific antibodies. These antibodies appear about three weeks after infection. These tests are very useful for tracking how the disease progresses and whether treatment is working.

A fourfold increase in the antibody level (called the titre) suggests the infection is active and progressing. A fourfold decrease in the titre after treatment suggests the therapy is working well. These tests use agglutination and haemagglutination methods to detect the antibodies.

Treponemal Tests: TPHA

The TPHA (Treponema pallidum Haemagglutination Assay) test detects antibodies that react specifically with T. pallidum antigens. Doctors use this test to confirm a positive VDRL or RPR result. However, this test is not used to monitor the progress of treatment, because treponemal antibodies often remain positive for years — or even permanently — even after a successful cure.

The one exception is congenital syphilis. In those cases, the TPHA test can be useful in monitoring the baby’s response to treatment. According to the Mayo Clinic’s syphilis diagnosis and treatment guide, combining both types of tests gives the most accurate picture of the infection.

What Do the Results Mean?

Getting your results back can feel confusing. Here is a simple breakdown of what different outcomes typically mean.

Positive VDRL/RPR, Confirmed by Positive TPHA

This result strongly suggests a current or past syphilis infection. Your doctor will assess which stage you are in and recommend the right course of treatment. In Canada, syphilis is treated with antibiotics, most commonly penicillin.

Positive VDRL/RPR, Negative TPHA

This is called a biological false positive. It means the non-treponemal test reacted to something other than syphilis. The test reagent contains cardiolipin, lecithin, and cholesterol, which can cross-react with antibodies from other conditions.

Conditions that can cause false positive results include:

• Autoimmune diseases such as lupus or antiphospholipid syndrome
• HIV infection
• Intravenous drug use
• Pregnancy
• Older age (about 10% of people over 70 may show false positives)
• Tuberculosis
• Certain cancers
• Malaria
• Viral infections such as hepatitis or infectious mononucleosis
• Hansen’s disease (leprosy)

Negative Result

A negative result does not always mean you do not have syphilis. False negatives can occur in the very early stages of infection, before antibodies have had time to develop. They can also occur in people living with HIV or those with weakened immune systems. Therefore, if you have had recent unprotected sex or suspect exposure, talk to your doctor even if your first test is negative.

No Special Preparation Needed

One of the simplest things about the syphilis blood test is that it requires no preparation. You do not need to fast beforehand, and there are no special instructions to follow. A healthcare provider draws a small sample of blood, typically from a vein in your arm, and sends it to a lab for analysis.

Results are usually available within a few days, depending on your province and the laboratory used. Your family doctor or the clinic where you were tested will contact you with results and next steps.

Monitoring Children with Congenital Syphilis

Babies born to mothers who tested positive for syphilis, or babies diagnosed with congenital syphilis, require ongoing monitoring. Healthcare providers check these children every two to three months until the antibody titre falls to a negative level. This close follow-up is an important part of ensuring the baby’s full recovery.

The World Health Organization’s syphilis fact sheet highlights the elimination of congenital syphilis as a global health priority. Canada has its own national targets for reducing congenital syphilis rates through improved prenatal screening programmes.

When to See a Doctor

You should speak with your family doctor or visit a walk-in clinic for a syphilis blood test if any of the following apply to you:

• You have had unprotected sexual contact with a new or unknown partner
• You or your partner have had multiple sexual partners
• You have noticed unusual sores, rashes, or lesions on your body
• You are pregnant or planning to become pregnant
• You have been notified by a partner that they tested positive for syphilis
• You are a man who has sex with men — Canadian guidelines recommend regular testing for this group
• You are living with HIV

Most provincial health plans in Canada cover syphilis testing when it is medically indicated. Walk-in clinics, sexual health clinics, and your family doctor’s office can all arrange a test. If you are unsure where to go, call Health Link (811) in many provinces for guidance.

Remember, syphilis is highly treatable, especially when caught early. Getting tested is a straightforward and responsible step for your health and the health of your partners.

Frequently Asked Questions

Key Takeaways

• A syphilis blood test detects antibodies your body makes in response to Treponema pallidum infection.
• Two main types of tests are used: VDRL/RPR for monitoring the disease and treatment response, and TPHA for confirming a positive result.
• Syphilis has four stages, some of which have no symptoms — making regular testing important for sexually active Canadians.
• Congenital syphilis can pass from parent to baby and requires routine prenatal screening, which is covered under most provincial health plans.
• False positive and false negative results are possible; always discuss your results with a qualified healthcare provider.
• Syphilis is fully treatable with antibiotics, especially when caught early through a simple blood test.
• If you have any concerns about syphilis or other STIs, speak with your family doctor or visit a walk-in clinic — getting tested is the right thing to do for your health and your community.