What is the Syphilis Testing Window?

Syphilis is a sexually transmitted infection (STI) caused by a bacteria called Treponema pallidum. In the 1990s, North America was close to eradicating the disease, but since 2014, Canada has experienced a steep increase in infection rates due to many contributing factors such as reduced funding for prevention and treatment, as well as barriers to accessing healthcare.

Currently, syphilis is circulating throughout the Canadian population with an increase in reported cases among heterosexual women. However, gay and bisexual men continue to be disproportionately affected by the disease and other sexually transmitted and bloodborne infections.

Although it can be considered one of the most serious STIs, it’s also both preventable and curable. However, if left untreated, it can cause serious health problems and even death. 

Here’s what you need to know about the syphilis testing window — in other words, how to ensure accurate results on your syphilis STI test and minimize the risk of false negatives.

Symptoms of syphilis: What you need to know

Syphilis is now one of the most common STIs in Canada, among gonorrhea and chlamydia. Understanding the symptoms of syphilis is crucial for early detection and treatment. Knowing when and how to test for syphilis is equally important, as accurate testing and early diagnosis can prevent the severe complications associated with untreated infections.

Syphilis is transmitted through: 

• Sexual activity (including vaginal, anal, or oral sex)
• Sharing sex toys
• Contact with a syphilis sore (called a chancre) or rash
• During pregnancy, from the mother to the fetus
• Childbirth, if a baby comes in contact with lesions or fluids
• Direct transfer such as needle sharing or blood transfusions (Note: In Canada, all donated blood is screened for syphilis)

Practicing safer sex using condoms or dental dams can help lower the chances of contracting or transmitting syphilis, as can STI testing. Not everyone with syphilis experiences symptoms, which means it’s easy to pass it on to someone else — that’s why regular STI testing is so important. Aim to get tested every year, or more often if your situation has changed, such as a relationship status, sexual activity, or sexual partner(s).

While, as mentioned, not everyone experiences symptoms with a syphilis infection, particularly in the early stages. When symptoms do arise, the early stages may include:

• Headaches
• Painless chancre
• Rashes
• Fever
• Difficulty getting and maintaining an erection
• Changes to one’s personality

But other symptoms can arise, depending on how long the disease has been left undetected and untreated and, therefore, which stage syphilis is in.

Here’s how each of the four stages present:

• Primary syphilis: A single painless ulcer (chancre) or multiple painful lesions at the site of infection 
• Secondary syphilis: Skin rash, lesions, swollen lymph nodes, fever, patchy hair loss
• Latent syphilis: No symptoms, but can damage organs
• Tertiary syphilis: This can last for decades after contracting the infection, leads to damage to organs like the heart, brain, and blood vessels, and can cause serious health problems including tumors, blindness and death

The syphilis testing window

The syphilis testing window refers to the period between when someone contracts syphilis and when a test can reliably detect the infection. Typically, the incubation period for syphilis ranges from 30 to 90 days, depending on whether symptoms are present.

If you’re experiencing symptoms such as genital sores (chancres), they often appear within three weeks of exposure. In this case, a blood test can detect syphilis one to two weeks after the sore appears, so it’s best to get tested four to five weeks after exposure.

If you don’t have symptoms, it’s recommended to wait 90 days after exposure to get tested or to retest for a more accurate result.

In the meantime, whether you have symptoms or not, if you’re feeling anxious about potential exposure, consider speaking with a healthcare provider. They can offer advice, help you understand your options and guide you on the best course of action to protect your health.

Types of tests

Depending on the symptoms, your healthcare provider may recommend a diagnostic test via a blood test or sample visible lesions. Less commonly, tests can also be done on samples of cerebrospinal fluid.

Serologic testing

Healthcare providers use serologic testing to measure the presence and amount of antibodies in the blood to diagnose and monitor syphilis and other infectious diseases. 

There are no perfect tests in detecting syphilis. Some are more sensitive than others at detecting T. pallidum or the antibodies against the bacteria, but there can be false results with any test. This is why the Public Health Agency of Canada provides healthcare providers guidance in the next steps. In Canada, the type of test(s) to diagnose syphilis may differ between provinces and territories but may include one or a combination of the following tests:

• Venereal disease research laboratory (VDRL) 
• Rapid plasma reagin (RPR) 
• Trepomenal-specific enzyme imminoassay (EIA) 
• Fluorescent trepomenal antibody absorption (FTA-ABS)
• T. pallidum particle agglutination (TP-PA) 
• Chemiluminescent immunoassay (CIA)
• Microhemagglutination assay for T. pallidum  (MHA-TP)
  

The non-treponemal tests(VDRL and RPR) look for antibodies against cardiolipin, a type of lipid in the bacteria membrane, in the blood or cerebrospinal fluid (CSF). These tests are only positive after the first lesion or chancre develops, peaks in the first year, and then taper down. They can be undetectable in later stages of syphilis and, therefore, are not used to monitor disease progression. This type of test requires a trained lab technician. 

Treponemal tests (EIA, FTA-ABS, TP-PA, CIA, and MHA-TP) screen for antibodies directly against T. pallidum. A positive treponemal test can be detected early, but cannot tell the difference between a new exposure and a previously treated infection. So once this type of test is positive, it will remain positive for life and it is not an appropriate test to monitor disease progression. 

Rapid tests are approved and available to Canadians to help detect syphilis early and improve accessibility of testing. 

False positives may occur during serologic testing for those with conditions such as pregnancy, collagen-vascular disease, Lyme Disease, or injection drug use.

Direct tests and lesion samples

Also known as non-serological tests, direct tests are executed on lesions in the primary and secondary stages of syphilis. Direct tests are used less often than serologic testing methods and may not be offered at every laboratory due to the time sensitivity and required technician skill set and reliability of the tests. These types of tests can include darkfield microscopy, immunofluorescent antibody staining, Nucleic Acid Amplification Tests (NAAT), immunohistochemistry, or silver staining. A healthcare provider may conduct a physical examination including a neurologic exam if they suspect latent or tertiary syphilis. 

Cerebrospinal fluid (CSF)

The cerebrospinal fluid Venereal Disease Research Laboratory (CSF-VDRL test) is performed to diagnose syphilis in its late stage, when the disease may have reached the brain or spinal cord. That’s because untreated syphilis can cause neurosyphilis, an infection in the central nervous system. The CSF-VDRL test (also called a neurosyphilis test) looks for antibodies in CSF to diagnose neurosyphilis — meaning, syphilis in its late stage.

Congenital syphilis

Pregnant women with syphilis could pass the disease onto their babies, which can cause miscarriage, stillbirth, premature birth, or future health problems for the baby, such as brain or nerve problems, and bone or joint abnormalities, among others. 

An assessment for congenital syphilis should be performed at 20 weeks of pregnancy with a detailed obstetrical ultrasound, or in infancy for children presenting signs or symptoms. The condition can be managed through a consultation with an obstetric/maternal-fetal specialist. 

Importance of early testing

Early testing for syphilis helps prevent the spread of the infection. Identifying and treating the STI means you won’t transmit it to others and can prevent spreading it to a newborn. If left untreated, syphilis can cause permanent damage to your health, such as neurosyphilis (an infection in the central nervous system that affects the brain and spinal cord) and in some cases, death.

Syphilis treatment

Syphilis can be easily cured in the early stages of the infection with penicillin. It’s an antibiotic medicine that can kill T. pallidum, the bacteria responsible for syphilis. Alternatives such as doxycycline or ceftriaxone can be used for people with penicillin allergies. If there are concerns about neurologic involvement such as neurosyphilis, a neurologist and/or infectious disease specialist may also be involved in your care path.

If you think you have an STI but don’t have access to a primary care provider. Maple can help. We’ll connect you virtually with a primary care provider — like a Canadian-licensed doctor or nurse practitioner — who can diagnose you and give you insight on next steps. Primary care providers — like doctors and nurse practitioners — are available 24/7/365 in minutes, and you can connect over secure text, audio, or video call. You’ll always feel confident that your conversation stays between you and your provider.

Taking control of your sexual health is essential, and understanding the syphilis testing window is a key part of that process. Early detection and treatment not only protect your health but also prevent the spread of this serious infection to others. Whether you’re experiencing symptoms or simply want peace of mind, timely testing can make all the difference. 

The information presented here is for educational purposes and is not meant to replace the advice from your medical professional. Virtual care is not meant for medical emergencies. If you are experiencing an emergency like chest pain or difficulty breathing, for example, please call 911 or go to your nearest emergency room.