Syphilis

How syphilis spreads

Treponema pallidum passes through tiny breaks in the skin or mucous membranes during contact with a syphilis sore or the moist rash of secondary syphilis. This happens during:

• vaginal, anal and oral sex
• kissing, if there is a sore in or around the mouth (less common)
• pregnancy, from mother to baby (congenital syphilis)
• rarely, sharing needles or blood transfusion (blood is screened in the US)

Syphilis is not spread through toilet seats, doorknobs, swimming pools, bathtubs, shared clothing or eating utensils. People are most infectious in the primary and secondary stages. Having syphilis sores also makes it easier to catch and pass on HIV.

Syphilis stages and symptoms

Syphilis is called "the great imitator" because its signs can look like many other diseases. Symptoms come and go, and many people never notice them.

Primary syphilis: the chancre

• a firm, round, painless sore, usually single, at the site of entry: penis, vulva, vagina, cervix, anus, rectum, lips or mouth
• appears 10 to 90 days after exposure, typically around 3 weeks
• often with swollen, painless lymph nodes nearby
• heals by itself in 3 to 6 weeks, even without treatment, but the infection continues

Sores inside the vagina, rectum or mouth often go unnoticed.

Secondary syphilis: the rash

Weeks to a few months later, the bacteria spread through the body:

• a non-itchy rash of rough, red or reddish-brown spots, classically on the palms of the hands and soles of the feet, but it can cover the trunk and be faint
• fever, sore throat, tiredness, muscle aches and headache
• swollen lymph nodes throughout the body
• patchy hair loss ("moth-eaten" scalp, thinning eyebrows)
• gray-white patches inside the mouth (mucous patches)
• raised, moist, wart-like gray patches in warm areas such as the groin and anus (condylomata lata), which are highly infectious

These signs also clear without treatment within weeks, and may come back during the first year.

Latent syphilis

No signs or symptoms. Only a blood test shows the infection. It can last for years.

• Early latent: infection within the past 12 months.
• Late latent or unknown duration: longer than 12 months.

Tertiary syphilis

In about 15% to 30% of people who are never treated, serious damage appears 10 to 30 years later:

• gummas: destructive soft lumps in skin, bone, liver or other organs
• cardiovascular syphilis: inflammation of the aorta, leading to aortic aneurysm and valve leaks
• late neurosyphilis: dementia, personality change, and tabes dorsalis (loss of position sense, shooting pains, unsteady walking)

Neurosyphilis, ocular and otic syphilis

The bacteria can reach the nervous system, eyes or ears at any stage, including early. Symptoms include headache, confusion, stroke, uveitis (eye inflammation), vision loss, hearing loss and tinnitus. These are medical urgencies. See neurosyphilis.

Syphilis in women and in pregnancy

In women, the chancre is often hidden inside the vagina or on the cervix, so the first sign may be the secondary rash or only a positive screening test. Syphilis in pregnancy can cause miscarriage, stillbirth, premature birth and congenital syphilis, in which babies may have rash, bone problems, enlarged liver, anemia, deafness or developmental problems, or may die shortly after birth. US cases of congenital syphilis have increased more than tenfold over the past decade.

The CDC recommends testing all pregnant people at the first prenatal visit, and again at 28 weeks and at delivery for those at higher risk or living in high-prevalence areas. Treating with penicillin at least 30 days before delivery prevents most congenital infections.

Syphilis vs other genital sores

The secondary rash can be mistaken for pityriasis rosea, drug rashes, psoriasis or a viral illness.

How syphilis is diagnosed

Syphilis is diagnosed with two types of blood test together:

• Treponemal tests (such as TP-PA, EIA or CIA): detect antibodies to T. pallidum. They usually remain positive for life, even after cure.
• Non-treponemal tests (RPR or VDRL): measure a level (titer) that rises with active infection and falls after treatment. They are used to monitor response.

A positive result on both indicates current or past infection. Early tests can be negative in the first few weeks after a sore appears, so repeat testing may be needed. A swab of a sore can be tested by PCR or dark-field microscopy where available. A lumbar puncture tests spinal fluid when neurosyphilis is suspected.

Anyone diagnosed with syphilis should also be tested for HIV, gonorrhea and chlamydia.

Treatment

Syphilis is curable. Penicillin G benzathine given as an injection into the muscle is the standard treatment:

• Primary, secondary and early latent syphilis: a single injection.
• Late latent syphilis or unknown duration: three injections, one week apart.
• Neurosyphilis, ocular or otic syphilis: IV penicillin in hospital for 10 to 14 days.
• Pregnancy: penicillin is the only recommended treatment. People allergic to penicillin are desensitized and then treated with penicillin.
• Non-pregnant people with penicillin allergy: doxycycline tablets may be used for some stages, with close follow-up.

Within 24 hours of the first injection, some people get fever, chills, headache and muscle aches. This Jarisch-Herxheimer reaction is caused by bacteria dying, is not an allergy, and settles within a day.

After treatment

• Avoid sexual contact until sores or rash have fully healed and at least 7 days after treatment.
• Recent sexual partners (within 90 days of diagnosis for early syphilis, and longer for later stages) should be tested and treated.
• Repeat RPR or VDRL tests at 6 and 12 months confirm a fourfold drop in titer. People with HIV are followed more often.
• Treatment cures the infection but does not reverse organ damage that has already occurred, and it does not protect against reinfection.

Prevention

• Use condoms consistently. They reduce but do not eliminate risk, because sores can be outside the covered area.
• Get regular testing: at least yearly for sexually active men who have sex with men, people with HIV and others at increased risk, and every 3 to 6 months for those at highest risk.
• Doxy-PEP: the CDC recommends that men who have sex with men and transgender women with a recent STI consider taking doxycycline within 72 hours after condomless sex, which reduces syphilis, chlamydia and gonorrhea.
• Tell partners after a diagnosis so they can be treated.
• Get tested in every pregnancy.

Frequently asked questions

What are the first signs of syphilis?

The first sign is usually a single, firm, painless sore called a chancre on the genitals, anus or mouth, about 3 weeks after exposure. It heals on its own in a few weeks, which is why many people miss it. Nearby lymph nodes may swell.

What does a syphilis rash look like?

The secondary syphilis rash is usually rough, red or reddish-brown spots that do not itch. It often appears on the palms and soles but can spread over the body. It may be faint and come with fever, swollen glands, sore throat and patchy hair loss.

Can syphilis be cured?

Yes. Penicillin injections cure syphilis at every stage. A single injection is enough for early syphilis. Treatment stops the infection but cannot undo damage already done to organs, and you can catch syphilis again after cure.

How long can you have syphilis without knowing?

Years. After the sore and rash fade, syphilis can stay latent with no symptoms for many years while still damaging organs in some people. This is why regular blood tests are recommended for people at risk and in every pregnancy.

How is syphilis transmitted?

Syphilis spreads through direct contact with a syphilis sore or rash during vaginal, anal or oral sex, and from a pregnant person to the baby. It is not spread by toilet seats, pools, shared clothing or utensils.

What are syphilis symptoms in women?

Women often have no noticeable first sore because it may be inside the vagina or on the cervix. Later they may have a rash on the palms or soles, fever, swollen glands, hair loss or wart-like patches around the vulva or anus. Many are diagnosed only through screening.