Treatment for Infectious Syphilis

Advisory Alert

August 20, 2021

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To: Community Health Care Providers


The purpose of this Advisory Alert is to provide an update regarding the importance of proper treatment of diagnosed infectious Syphilis cases. Due to a recent increase in diagnosed cases in our community, this alert will serve as reminder of treatment for cases as per the Canadian Guidelines on Sexually Transmitted Infections.

Local Epidemiology

The number of cases of infectious syphilis has been on the rise across Canada, provincially and locally over the last several years. Since 2014, a total of 100 cases have been confirmed in the Sudbury & Districts area, with 33 in each of 2019 and 2020 and 10 cases for the first six months of 2021.

Etiology, Transmission, Signs and Symptoms

Syphilis is a sexually transmitted infection (STI) caused by the bacterium Treponema pallidum. Clinical manifestations vary by stage (primary, secondary, latent, tertiary). Primary, secondary, and early-latent syphilis are considered infectious (see Table 1, below) and are the focus of this alert. The main mode of transmission is by vaginal, anal, and oral sexual contact. Vertical transmission can occur, resulting in congenital syphilis.

Direct contact with lesions of primary and secondary syphilis pose the greatest risk of transmission. Not all lesions may be readily apparent. A high proportion of individuals fail
to recall primary chancre. Signs and symptoms may be modified in the presence of HIV

Table 1: Clinical Manifestations of Infectious Syphilis by Stage of Infection

StageClinical ManifestationsIncubation PeriodImage
PrimaryChancre, regional lymphadenopathy3 weeks (3-90 days)Clinical Manifestations of Infectious Syphilis by Stage of Infection - 3 weeks (3-90 days)
SecondaryRash, fever, malaise, lymphadenopathy, mucous lesions, condyloma lata, patchy or diffuse alopecia, meningitis, headaches, uveitis, retinitis2-12 weeks (2 weeks to 6 months)Clinical Manifestations of Infectious Syphilis by Stage of Infection - 2-12 weeks (2 weeks to 6 months)
Early LatentAsymptomatic˂1 year

Diagnosis: Laboratory Testing

  1. Testing from lesions of primary and secondary syphilis: use direct fluorescence for detection of T. pallidum. Submit serous exudates from suspected lesions or chancres obtained in accordance with the instructions in the Direct Fluorescence Kit. The slide is to be labelled with the patient’s full name and date of birth. Use the General Test Requisition from Public Health Ontario Laboratory available at:
  2. Serology: indicated for routine diagnosis of suspected syphilis cases, monitoring of treatment of diagnosed syphilis, and as part of prenatal screening, and donor screening. Submit serum for analysis along with a completed General Test Requisition as above.

Long acting benzathine penicillin is required to adequately treat infectious syphilis and achieve detectable serum levels of penicillin for two (2) to four (4) weeks. A longer course of treatment is required to cure infections of longer duration (late latent and/or tertiary syphilis).

Short acting penicillin agents are not adequate to cure syphilis. Alternative treatments (e.g. doxycycline, ceftriaxone) may take longer and individuals should be advised to abstain from sexual contact until treatment of the index case and (if indicated) all current partners has been completed and ideally for seven (7) days after completion of treatment.

Note: To avoid unnecessary retreatment, obtain and document prior history of treatment for syphilis and prior serologic results.

Table 2: The following table outlines the preferred treatment for infectious syphilis:

PatientPreferred treatment
All non-pregnant adults with primary, secondary or early latent syphilisBenzathine penicillin G-LA 2.4 million units IM as a single dose
Epidemiological treatment* of all sexual contacts in the preceding 90 days to primary, secondary or early latent syphilis
Pregnant women with primary, secondary or early latent syphilisBenzathine penicillin G-LA 2.4 million units IM as a single dose [B-II]
Benzathine penicillin-LA G 2.4 million units IM as a single dose weekly for two (2) doses [C-III]
(Manage people diagnosed with infectious syphilis during pregnancy in consultation with an obstetric/maternal-fetal specialist)
*Refers to treatment provided when diagnosis is considered likely on clinical, laboratory or epidemiologic grounds, but before results of confirmatory tests are known

Please consult the Canadian Guidelines on Sexually Transmitted Infections for additional guidance at:

Health care practitioners can refer for or have access to publicly funded syphilis treatment by contacting the Sexual Health Clinic using the contact information below. Patients who are referred to the clinic for treatment must have a prescription which includes staging.


Report all confirmed and suspected cases of syphilis to Public Health Sudbury & Districts at 705.522.9200, ext. 482.


Original Signed By

Dr. Penny Sutcliffe
Medical Officer of Health and Chief Executive Officer

NOTE: All Advisory Alerts are found on our website.

This item was last modified on August 20, 2021