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Co-infections and Related Conditions (CRC)

CTNPT 036: Novel Assay for Syphilis

Using a novel assay to detect syphilis infection early in asymptomatic men who have sex with men (MSM) undergoing STI screening

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About the study (objectives)

This pilot study is looking at the acceptability and performance of a new test that could allow for earlier detection of syphilis in men who have sex with men (MSM) who do not yet have symptoms. This is important, as earlier diagnosis in people who may have the infection but do not know it would allow for earlier treatment, potentially preventing the development of troublesome symptoms and complications; also, it could prevent passing the infection to others. This study aims to illuminate some of the missing information about syphilis testing, potentially leading to better and faster ways of diagnosing the infection.

About the disease/condition (background/context)

There has been a recent spike in syphilis cases reported in Canada and many other countries. These record-high syphilis rates disproportionately affect MSM and about two thirds of syphilis cases in Canada are in MSM living with HIV, and rates of reinfection are also high. Syphilis infection can cause serious complications as well as increase risk of both passing and acquiring HIV.

The current screening method for syphilis detects antibodies, the immune system’s response to an infection. However, it can take up to 6 weeks for the immune system to respond with enough antibody to be detected by the test. This means that people may appear syphilis-negative and be unknowingly passing the infection along during that time period. Detection of syphilis in people living with HIV may take even longer.

In response to the current testing tool and to the resurgence of syphilis as a public health concern, Dr. Troy Grennan is leading a study to evaluate the use of polymerase chain reaction (PCR), a technique which can detect the presence of syphilis DNA using a swab of an affected area, or in the blood. As a pilot study, this investigation is primarily concerned with how participants perceive the test — whether they find it acceptable and whether they would be willing to do it again.

Study Approach (methodology)

The study will recruit 406 sexually active MSM living with or without HIV at several HIV and STI clinics in Vancouver. During routine STI screening visits and testing, participants will self-collect anal and throat samples, blood samples will be drawn, and physical examination will be completed. The self-collected swabs will be tested using the PCR technique and the blood samples will be analyzed using both the current and PCR tests. A questionnaire will also be administered that will collect information about clinical information, sexual history, and syphilis swab acceptability.

The research team will analyze the data to determine the proportion of participants who had a favourable opinion of the test and who would do it again. The team will also look at how the novel PCR test compares to traditional testing and whether new syphilis cases are diagnosed earlier with the new test. The outcomes of this study will help researchers decide whether they should proceed with a larger clinical trial and implementation of the new test.

Eligibility criteria


  • Self-identify as MSM;
  • Age 19 years or older;
  • Self-reported history of condomless anal and oral sex in the last three months

Not Allowed:

  • Confirmed syphilis infection in the three months prior to visit;
  • Presence of signs, symptoms and/or clinical history consistent with current syphilis infection;
  • Current or recent use (i.e. within last two weeks) of any antibiotic from the following classes with the potential to treat or prevent syphilis: penicillins, tetracyclines, cephalosporins, macrolides;
  • Inability to provide informed consent.

Additional Information

For more information about the study, please contact the principal investigator.

Participating Sites


BCCDC Provincial STI clinic
655 West 12th Ave

Principal Investigator

Dr. Troy Grennan, MD, FRCPC
Physician Lead, HIV/STI Program
BC Centre for Disease Control
655 West 12thAvenue, Vancouver, BC
V5Z 4R4


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