Syphilis testing update and screening recommendations

To: Ottawa Physicians and Nurse Practitioners
Date: July 29, 2025
From: Dr. Michelle Foote, Associate Medical Officer of Health
Subject: Syphilis testing update and screening recommendations

Public Health Ontario Laboratory (PHOL) has updated its testing approach for syphilis lesion specimens. This alert provides an overview of the new testing protocol, current epidemiologic trends, and screening recommendations.

Changes to syphilis testing for lesion specimens

Effective July 7, 2025, PHOL has introduced polymerase chain reaction (PCR) for detecting Treponema pallidum in skin and mucosal lesion specimens. PCR testing will replace direct fluorescence antibody (DFA) testing; DFA will be discontinued on August 9, 2025. PCR testing should be used in conjunction with syphilis serology.

PCR testing is more sensitive compared to DFA and offers improved turnaround time (up to four business days), supporting early and accurate detection of syphilis. PCR is available for lesion-based specimens only. It is recommended for individuals with suspected primary syphilis, particularly when a chancre is present. It may also aid in secondary syphilis assessment, though diagnosis is typically based on serology, clinical findings, and risk factors.

Acceptable specimens include swabs of lesion or lesion exudates from skin or mucosal sites placed in Universal Transport Media (UTM). To order swabs and transport media for syphilis PCR testing, use the PHO Specimen Containers and Supplies Order Form. Submit all specimens with a completed General Test Requisition, ensuring the lesion site and “syphilis PCR – lesion” are clearly indicated. Additional information can be found at Syphilis PCR – Public Health Ontario.

Current Epidemiologic Trends

According to the PHO Syphilis and Congenital Syphilis Surveillance Report, rates of infectious syphilis have been steadily increasing in Ontario for more than a decade. Between 2014 and 2023, provincial rates more than tripled, rising from 6.5 to 20.9 per 100,000 population.

While men who have sex with men (MSM) continue to represent a large proportion of cases, recent increases have been most pronounced among women of reproductive age (from 3.8% to 18.0% over the same period). This shift has contributed to a rise in congenital syphilis across the province from 3 cases in 2019 to a high of 23 cases in 2022.

In Ottawa, syphilis trends reflect the provincial pattern. Local rates among females of reproductive age have increased in recent years, and one confirmed case of congenital syphilis was reported in 2023. For further information, please see Infectious Diseases Data and Reports - Ottawa Public Health.

Testing and Screening Recommendations

Syphilis serology remains the standard method for routine screening, diagnosis of suspected infection, and monitoring treatment response.

All pregnant individuals should be screened with serology during the first trimester or at the first prenatal visit. For those with ongoing or elevated risk, repeat testing should be considered at 28–32 weeks gestation and again at delivery. When investigating congenital syphilis, maternal serum should be submitted along with the newborn’s specimen on a separate requisition. For more information on prenatal screening, please see PHO Prenatal Serology.

Screening is also recommended for individuals with risk factors, including new or multiple sexual partners or upon patient request. For those with multiple partners or ongoing risk, repeat screening every 3 to 6 months is advised. For more information on syphilis screening, refer to the Canadian Guidelines on Sexually Transmitted Infections.

Syphilis is reportable to Ottawa Public Health

Monday to Friday from 8:30 am to 4:30 pm: Call 613-580-2424, extension 24224 and leave a detailed, confidential message including your contact information; or fax 613-580-9640. A reporting form and a generic webform are available for your convenience.

Resources:

• Ottawa Public Health: Order free STI medications and free condoms for clinic waiting rooms.
• PHAC: Sexually transmitted and blood-borne infections: Guides for health professionals (formerly Canadian Guidelines on STIs).
• Public Health Ontario Laboratory: Test Information Index. Scroll down to S for Syphilis.
• Public Health Ontario: Syphilis.
• GetaKit.ca Online HIV and STI Testing Service: eligible persons in Ottawa can obtain clinically indicated HIV and STI testing services through GetaKit.ca, including at-home HIV self-tests, and requisitions for laboratory-based testing for chlamydia, gonorrhea, syphilis, hepatitis C, and HIV.