Syphilis is actually a single disease made up of several different stages. The symptoms of syphilis depend on the stage of disease.
Primary syphilis: In most cases, the only noticeable symptom of primary syphilis is a painless sore (called a "chancre") that develops within two to six weeks after someone has been infected with T. pallidum. The sore usually develops on the penis, vulva, vagina or anus. It can also develop on the cervix, tongue, lips, and other parts of the body. The sore usually heals within a few weeks without treatment. Here's what a syphilis sore/chancre can look like...
HIV is much easier to transmit when these sores are present. Someone who is HIV positive and has a syphilis sore is much more "infectious"—that is, likely to transmit his or her HIV—than someone who does not have a chancre. Similarly, HIV-negative people who have a syphilis sore are at a much higher risk of becoming infected with HIV if they have unprotected sex with someone who is HIV positive.
If you have primary syphilis and do not receive treatment, it's possible that your infection will progress to secondary syphilis.
Secondary syphilis: The most common symptom of secondary syphilis is an outbreak of small, pox-like lesions—usually brownish-pink in color—that seem like a non-itchy rash when clustered together. They can appear anywhere on the body, but a rash and lesions on the palms and soles of the feet are classic symptoms of secondary syphilis. Here's what the rash can look like...
These lesions are highly contagious! They can spread the bacteria if the skin is broken. They can also take several weeks or months to heal, and possibly recur, without treatment.
Secondary syphilis can occur months to years after primary syphilis, and can last two years or more. Other possible symptoms of secondary syphilis include fever, fatigue, soreness and aching.
Latent syphilis: Latent (hidden) syphilis is diagnosed when a person has antibodies to the bacterium but doesn't have any symptoms of the infection. Even though someone with latent syphilis generally isn't considered infectious—meaning that they are unlikely to transmit the bacteria to others—treatment is recommended to prevent serious late-stage disease complications.
Latent syphilis can either be early latent or late latent, depending on how long someone has had the infection. People with late latent syphilis (those who have been infected for at least a year) or latent syphilis of unknown duration (those who don't know how long they've been infected) require more aggressive treatment than those who with early latent infection (those who have been infected for less than a year).
Tertiary syphilis: If primary, secondary or latent syphilis is not treated, the bacteria can spread and damage internal organs, including the brain, nerves, eyes, heart, blood vessels, liver, bones and joints. This can lead to a variety of serious health problems, including stroke, paralysis, aneurysms, and heart disease.
Neurosyphilis: This occurs when T. pallidum infects the brain or spinal cord (central nervous system). Infection can occur during any syphilis stage and can cause serious neurological damage, including paralysis, numbness, gradual blindness and deafness. Neurosyphilis can be serious enough to cause permanent disability or death. Studies have found that HIV-positive people infected with T. pallidum are more likely to develop neurosyphilis, even during the early stages of infection.