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Reporting Obligations

Individuals who have or may have syphilis shall be reported as soon as possible to the local Health Unit.

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Aetiologic Agent

The spirochete Treponema pallidum, subspecies pallidum is the infective agent.

Clinical Presentation

An acute and chronic treponemal disease characterized clinically by a primary lesion, a secondary eruption involving skin and mucous membranes, long periods of latency, and late lesions of skin, bone, viscera, the central nervous system (CNS) and cardiovascular system.

Four stages in syphilis infection include:  primary, secondary, latent and tertiary.

Primary syphilis is characterized by one or more superficial ulcerations or chancres at the site of exposure and regional lymphadenopathy. The primary lesion usually appears 3 weeks after exposure.

Secondary syphilis generally develops following resolution of primary lesion. It is characterized by macular, maculopapular or papular lesions or a rash, typically involving the trunk, palms, and soles, generalized lymphadenopathy, fever, sore throat, malaise and mucosal lesions. A small number of cases may experience alopecia, meningitis, headaches, uveitis and retinitis.

Latent syphilis is serological evidence of infection in the absence of symptoms and is further defined as: Early latent syphilis, acquired within the preceding year, and Late latent syphilis, all other cases of latent syphilis. If left untreated, late latent syphilis can progress to tertiary syphilis.

Tertiary syphilis is rare, may manifest as gummas of the skin, musculoskeletal system, or internal organs, with cardiovascular and neurological involvement, and typically is not infectious.

During secondary, latent and tertiary stages of syphilis, the CNS can be infected causing neurosyphilis. Individuals with neurosyphilis can be asymptomatic or experience headache, vertigo, dementia, changes to their personality, and ataxia.

Primary, secondary, and early latent syphilis are considered infectious.

Symptoms and signs of syphilis may be modified in the presence of HIV co-infection. Persons co-infected with HIV may require a longer course of treatment.

Congenital syphilis can result in stillbirth, hydrops fetalis or preterm birth within the first 4–8 weeks of life.

Modes of Transmission

The primary mode of transmission is by sexual contact, including vaginal, oral and anal sex.

Transmission of syphilis from an infected mother to her infant can occur before or at the time of birth. Mother to fetus is most probable during early maternal syphilis, but can occur throughout the latent period. Infected infants may have moist mucocutaneous lesions that are more widespread than in adult syphilis and are a potential source of infection. Breastfeeding by mothers with primary or secondary lesions of syphilis carries a theoretical risk of transmission of syphilis to the baby.

Incubation Period

From 10 days–3 months; usually 3 weeks.

Period of Communicability

Communicability exists when moist mucocutaneous lesions of primary and secondary syphilis are present. Primary, secondary, and early latent syphilis are considered infectious. Direct (often intimate) contact with lesions of primary and secondary syphilis poses the greatest risk of transmission. Early latent syphilis is considered infectious because of the 25% chance of relapse to secondary stage.

Risk Factors/Susceptibility

Those who have had sexual contact with a known case of syphilis and in the following individuals: MSM, sex workers, those with street involvement/homeless, injection drug users, those with multiple sexual partners, those with a history of syphilis, HIV and other STIs, those originating from or having sex with an individual from a country with a high prevalence of syphilis.

Approximately 30% of exposures result in infection. Untreated infection leads to gradual development of immunity against T. palladium. Patients treated during the primary and secondary stages do not typically develop immunity and therefore are susceptible to reinfection.

Diagnosis and Laboratory Testing

Diagnosis of syphilis requires combination of history including epidemiologic risk factors or exposure, physical examination and laboratory tests as there is no single optimum diagnostic criterion. Refer to “Syphilis: Screening, Testing & Treatment algorithm.”

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Treatment and Case Management

Treatment is under the direction of the attending health care provider. Management depends on the stage of syphilis infection. Cases should refrain from sexual activity until treatment is completed and symptoms disappear. Refer to the “Canadian Guidelines on Sexually Transmitted Infections, evergreen edition” and “Syphilis: Screening, Testing & Treatment algorithm“.

If applicable, identify and treat sexual contacts, provide education about the infection and methods of preventing further spread and encourage testing for HIV and other STIs.

Patient Information

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Additional Resources

Syphilis – Sex & U (


Ministry of Health and Long-Term Care, Infectious Diseases Protocol, 2022.

Public Health Agency of Canada. “Canadian Guidelines on Sexually Transmitted Infections, evergreen edition.”

Heymann, D.L. Control of Communicable Disease Manual (19th Ed.). Washington, American Public Health Association, 2008.