Read condition-specific symptoms and clinical context for Treponema pallidum. The spiral bacterium behind syphilis, an infection that moves through stages and can go quiet for years.
PHAC describes T. pallidum as a spiral-shaped, microaerobic, non-spore-forming, motile bacterium measuring 6 to 20 micrometres in length and 0.1 to 0.2 micrometres in diameter, with a protoplasmic cylinder and cytoplasmic membrane bound by a thin peptidoglycan sacculus and outer membrane; although structurally double-membraned, its outer membrane lacks lipopolysaccharides and differs markedly from a typical Gram-negative outer membrane. It could not be grown in pure culture for more than a century, and a long-term tissue-culture system was only reported in 2018. WHO estimated 7.1 million new syphilis infections worldwide in 2020, and 1.1 million pregnant women estimated infected in 2022, resulting in over 390,000 adverse birth outcomes. This profile describes the subspecies pallidum, which causes venereal syphilis.
CDC describes the first stage as a single sore or multiple sores at the site where infection entered the body. PHAC gives a median incubation of 21 days with a range of 3 to 90 days.
Possible symptoms: A single sore or multiple sores (chancre); Sore that is usually painless; Sore that heals on its own in 3 to 6 weeks.
CDC notes the sore heals whether or not treatment is given, so disappearance of the sore is not evidence that the infection has gone. Diagnosis and treatment are clinical decisions.
CDC describes the second stage as skin rashes and/or sores in the mouth, vagina or anus. PHAC places it within 6 to 8 weeks after resolution of primary lesions.
Possible symptoms: Skin rash; Sores in the mouth, vagina or anus; Fever; Swollen lymph nodes; Sore throat; Hair loss; Headaches; Weight loss; Muscle aches.
CDC states the symptoms of this stage will go away whether or not treatment is received, and PHAC records that the acute manifestations typically resolve spontaneously even without therapy. Resolution again does not mean cure.
CDC describes the latent stage as a period when there are no visible signs or symptoms, and states that people can carry the infection for years without awareness.
PHAC describes latent syphilis as occurring between the resolution of secondary symptoms and the onset of tertiary syphilis, during which patients are asymptomatic. There is no symptom list for this stage and none is invented here. Latency is untreated ongoing infection, not recovery: PHAC records that approximately 15 to 40% of untreated people go on to develop tertiary disease, and that transplacental transmission can occur at any time during gestation. PHAC also notes sexual transmission occurs during the first 1 to 2 years after infection.
Latent infection is found by testing rather than by symptoms. Staging and treatment are clinical decisions and are not reproduced here.
CDC states that most people with untreated syphilis do not develop tertiary syphilis, but that when it occurs it can affect many different organ systems and would occur 10 to 30 years after infection began.
Possible symptoms: Problems affecting many organ systems; Heart and blood-vessel disease; Nervous-system disease.
CDC states that most people with untreated syphilis do not reach this stage. The figures above describe untreated infection, and treatment at any earlier stage changes that course.
Source check: 2026-09-20. Educational content; independent scientific review remains pending.