Syphilis

Syphilis is a bacterial infection that spreads through sexual contact and can cause serious health problems if left untreated. With early detection and proper antibiotic treatment, this infection can be cured before it causes lasting damage to the body.

Table of contents

• What is syphilis?
• How syphilis spreads
• Stages of syphilis
• Signs and symptoms
• Special forms: neurosyphilis, ocular, and otosyphilis
• Syphilis in pregnancy and newborns
• Who is at risk?
• How syphilis is diagnosed
• Treatment
• Prevention
• Complications of untreated syphilis

What is syphilis?

Syphilis is a sexually transmitted infection (STI) caused by bacteria called Treponema pallidum^[1][2]. This infection has been affecting people for hundreds of years and is sometimes called “the great imitator” because its symptoms can look like many other diseases^[2][4].

The infection develops in stages, and each stage has different signs and symptoms. Without treatment, syphilis can stay in the body for many years and cause serious damage to the heart, brain, and other organs^[1][2]. However, the good news is that syphilis can be cured with antibiotics, especially when caught early^[1][2].

Cases of syphilis are currently rising in the United States. In 2021, there were over 176,000 reported cases, which marked a 74% increase since 2017^[8]. Globally, the World Health Organization estimates that 8 million adults between 15 and 49 years old acquired syphilis in 2022^[5].

How syphilis spreads

Syphilis is caused by the bacterium Treponema pallidum. This bacteria is primarily transmitted through direct contact with syphilis sores during sexual activities^[8].

The infection spreads when you have vaginal, anal, or oral sex with someone who has syphilis^[1][3]. You can get syphilis through direct contact with a syphilis sore, which is called a chancre. These sores usually occur in, on, or around the penis, vagina, anus, rectum, lips, or in the mouth^[1].

A pregnant woman with syphilis can pass the infection to her unborn baby through the placenta during pregnancy or during childbirth. This is called congenital syphilis^[2][8]. The infection can also be transmitted through blood transfusions, though routine screening of donated blood makes this risk very low in the United States^[8].

Syphilis cannot be spread through casual contact with objects like toilet seats, doorknobs, swimming pools, bathtubs, or shared clothing or eating utensils^[8]. The bacteria are extremely fragile and cannot survive outside the body^[4].

People can transmit syphilis during the primary, secondary, and early latent stages. During the late latent and tertiary stages, syphilis cannot be transmitted through sexual contact, though a pregnant woman can still pass it to her baby^[8].

Stages of syphilis

Syphilis progresses through four different stages if left untreated. Each stage has its own characteristics and symptoms^[1][3].

Primary syphilis

The first stage happens two to 12 weeks after exposure to someone with syphilis^[3]. The first symptom is usually a small, painless sore called a chancre that appears about three weeks after infection^[2]. The chancre is usually firm, round, and painless^[1]. Most people develop only one chancre, but some may have multiple sores^[2].

The sore appears at the spot where the bacteria entered the body. Because the sore is painless, many people don’t notice it^[1]. The sore usually lasts 3 to 6 weeks and heals on its own, even without treatment^[1]. However, this does not mean the infection is gone. Without proper treatment with medication, the infection will move to the second stage^[3].

Secondary syphilis

This stage develops about one to six months after the syphilis sore goes away^[3]. The stage usually starts with a rash that can appear when the primary sore is healing or several weeks after it has healed^[1].

The rash can cover the entire body, including the palms of the hands and soles of the feet^[1][3]. The rash often looks rough, red, or reddish-brown and usually doesn’t itch^[1]. Sometimes the rash is so faint that people don’t notice it^[1].

Other symptoms during secondary syphilis may include fever, swollen lymph glands, sore throat, patchy hair loss, headaches, weight loss, muscle aches, and fatigue (feeling very tired)^[1][3]. Some people may also develop wart-like sores^[3].

These symptoms can last from 2 to 6 weeks and will go away on their own, whether or not you receive treatment^[1]. However, without the right treatment, the infection will move to the latent and possibly tertiary stages^[1].

Latent syphilis

The latent stage is a period when there are no visible signs or symptoms of syphilis^[1][3]. This stage can last for many years, even up to 20 years^[3]. Without treatment, the infection remains in the body, and some people may experience mild flare-ups from time to time^[3].

During this stage, the infection can silently damage the heart, bones, nerves, and organs^[3]. It is rare to pass syphilis to sexual partners during the latent stage^[3].

Tertiary (late) syphilis

Most people with untreated syphilis do not develop tertiary syphilis^[1]. However, about 20% of people without treatment progress to this late phase^[3]. This stage occurs 10 to 30 years after the infection began^[1].

When tertiary syphilis does happen, it can affect many different organ systems, including the heart and blood vessels, and the brain and nervous system^[1]. It causes a range of serious health problems that develop slowly and include brain damage, dementia, cognitive health problems, heart disease, movement disorders, muscle problems, nerve damage, seizures, and vision problems including blindness^[3]. In tertiary syphilis, the disease damages internal organs and can result in death^[1].

Signs and symptoms

Many people with syphilis do not notice any symptoms or the symptoms are so mild they go unrecognized^[5]. The symptoms vary depending on the stage of infection^[1].

In the primary stage, the main symptom is a single painless sore or multiple sores at the location where syphilis entered the body^[1]. These sores are usually firm, round, and painless, which is why many people don’t notice them^[1].

During the secondary stage, symptoms may include skin rashes and sores in the mouth, vagina, or anus^[1]. The rash typically appears on the palms of the hands and bottoms of the feet, looks rough, red, or reddish-brown, and usually doesn’t itch^[1]. Additional symptoms can include fever, swollen lymph glands, sore throat, patchy hair loss (especially on the head, beard, and eyebrows), headaches, weight loss, muscle aches, and fatigue^[1][3]. White patches may appear in the mouth^[3].

The latent stage has no visible symptoms, but the infection is still present in the body^[1].

In the tertiary stage, symptoms relate to organ damage and can include problems with the heart, brain, blood vessels, bones, joints, skin, liver, and other organs^[1][6]. These complications can appear many years after the initial infection^[6].

Special forms: neurosyphilis, ocular, and otosyphilis

Without treatment, syphilis can spread to the brain and nervous system, the eyes, or the ears at any stage of the infection^[1][8].

Neurosyphilis

Neurosyphilis occurs when syphilis affects the brain and nervous system^[1]. Signs and symptoms can include severe headache, muscle weakness and trouble with muscle movements, and changes to mental state such as trouble focusing, confusion, personality change, or dementia (problems with memory, thinking, and decision making)^[1].

Ocular syphilis

Ocular syphilis affects the eyes and can involve structures in both the front and back of the eye^[9]. It often presents as inflammation throughout the eye, but can also cause other eye problems^[9]. Signs and symptoms include eye pain, redness, changes in vision, or even blindness^[1]. Ocular syphilis can result in permanent vision loss^[9].

Otosyphilis

Otosyphilis affects the ears and typically presents with symptoms related to hearing and balance^[9]. Signs and symptoms may include hearing loss (which can be sudden and progress rapidly), ringing, buzzing, roaring, or hissing in the ears (called tinnitus), and dizziness or vertigo (feeling like you or your surroundings are moving or spinning)^[1]. Hearing loss can be in one or both ears and can become permanent^[9].

Syphilis in pregnancy and newborns

Congenital syphilis is the disease that happens when women pass syphilis to their babies during pregnancy or childbirth^[1][2]. A pregnant woman can pass the infection to her baby through the placenta or during delivery^[8].

There has been a concerning increase in cases of congenital syphilis in recent years. In the United States, there were over 2,800 reported cases in 2021, representing a 203% increase since 2017^[8]. Over 10 times as many babies were born with syphilis in 2022 compared to 2012^[21].

Syphilis during pregnancy is a serious issue. When not treated, treated late, or treated with the incorrect antibiotic, it results in 50 to 80% of cases with adverse birth outcomes^[5]. It can cause miscarriage, stillbirth, premature birth, and even infant death^[5][6][21].

Babies born with syphilis can experience rashes, inflammation in the organs, anemia (low red blood cells), bone and joint problems, neurological conditions including blindness, deafness, and meningitis (inflammation of the membranes around the brain and spinal cord), developmental delays, and seizures^[5]. Babies born with syphilis can face lifelong medical issues^[21]. Some of these symptoms may only be noticed later in life^[5].

All pregnant people should get tested for syphilis at their first prenatal checkup^[2][3]. Testing for syphilis is recommended for all pregnant patients so infections can be found and treated, preventing transmission to the baby^[21].

Who is at risk?

Sexually active people can get syphilis through vaginal, anal, or oral sex with someone who has the infection^[1]. Anyone who is sexually active can get syphilis^[1].

While cases of syphilis are increasing among all age groups and in both men and women, certain groups are disproportionately affected. Men who have sex with men account for 36% of all primary and secondary syphilis cases and nearly 47% of all male primary and secondary syphilis cases in 2021^[8]. The World Health Organization notes that key populations such as gay men and other men who have sex with men are disproportionately affected^[5].

People who have been infected with syphilis can get it again if they have sexual contact with someone who has the infection^[8].

How syphilis is diagnosed

The only way to confirm if you have syphilis is through testing^[1]. Testing is important because many infections are without symptoms or go unrecognized^[5].

Syphilis can be found through blood tests or by testing fluid taken from sores or swollen lymph nodes that occur during primary or secondary syphilis^[21]. The definitive methods for diagnosing early syphilis include direct detection tests that look for the bacteria in fluid from lesions or tissue^[9].

A diagnosis of syphilis typically requires the use of two laboratory blood tests: a nontreponemal test (such as the Venereal Disease Research Laboratory test or rapid plasma reagin test) and a treponemal test (which looks for antibodies specific to the syphilis bacteria)^[9]. Both types of blood tests are needed to confirm that a person has syphilis^[21].

If a healthcare provider thinks you have nervous system problems from syphilis, they might recommend testing cerebrospinal fluid, which is the fluid that surrounds the brain and spinal cord^[10]. A needle is used to take a sample of this fluid from between two bones in the back in a procedure called a lumbar puncture^[10].

If you have symptoms of syphilis, a doctor or nurse will check your penis, vagina, and anus for syphilis sores. They may use a swab (like a cotton bud) to collect a fluid sample from any sores. They will also check the rest of your body for other signs of syphilis like a rash, sores, or wart-like growths^[6].

You may be able to use a test that’s available without a prescription, sometimes called an at-home test, to see if you have syphilis^[10]. Self-test kits are available where you use the kit at home and send it to a laboratory to be tested^[6].

Treatment

Syphilis is simple to cure when it’s found and treated in its early stages^[10]. The infection can be cured with antibiotics^[1][2].

The preferred treatment at all stages is penicillin, an antibiotic medicine that can kill the bacteria that causes syphilis^[10][12]. Penicillin remains the drug of choice to treat syphilis and is the only recommended therapy for neurosyphilis, congenital syphilis, or syphilis during pregnancy^[9].

The recommended treatment for primary, secondary, or early-stage latent syphilis is a single shot of benzathine penicillin G^[10]. For adults and adolescents with early syphilis, benzathine penicillin G 2.4 million units given once by muscle injection is recommended^[12].

If you have had syphilis for longer than a year, you may need additional doses. For late latent syphilis or latent syphilis of unknown duration, benzathine penicillin G 2.4 million units is given by muscle injection weekly for three doses (a total of 7.2 million units)^[10][15].

If you are allergic to penicillin, your healthcare team may suggest another antibiotic or may recommend a process that safely helps your body get used to penicillin over time^[10]. When benzathine or procaine penicillin cannot be used (for example, due to penicillin allergy) or are not available, doxycycline 100 mg twice daily by mouth for 14 days or ceftriaxone 1 gram by muscle injection once daily for 10 to 14 days may be used^[12]. Doxycycline is preferred over ceftriaxone due to its lower cost and oral administration^[12].

The bacteria are made non-infectious on average within 24 hours of treatment with long-acting benzathine penicillin^[15]. People who are treated with alternative treatments may take longer to become non-infectious and should be advised to avoid sexual contact without a condom until treatment has been completed and ideally for seven days after completion of treatment^[15].

You will need to go back to the healthcare provider 6 and 12 weeks after starting treatment to be retested^[6]. It is important not to have sex (vaginal, anal, or oral) until you and your partner have finished treatment and tests have shown treatment has worked^[6].

In some people, treatment can cause flu-like symptoms such as a high temperature, headache, and aching muscles. This usually lasts for up to 24 hours^[6].

Prevention

Syphilis is a preventable disease^[5]. Using condoms consistently and correctly is the best way to prevent syphilis and many other sexually transmitted infections^[5].

Correct and consistent use of condoms during sex can prevent syphilis^[1][5]. The risk of sexual transmission can be reduced by using a latex or polyurethane condom^[2]. However, syphilis can also spread through contact with sores that are not covered by a condom^[5].

Other ways to help prevent sexually transmitted infections include limiting your sex partners, talking with your partner or partners about STIs before you have sex, and finding out if they are at risk^[17]. Remember that it is possible to have an STI and not know it^[17]. Wait to have sex with new partners until you have each been tested^[17].

Do not have sex if you have symptoms of an infection or if you are being treated for an STI^[17]. If you had sex without a condom, ask your doctor if taking a preventive medicine is recommended, as it may help prevent certain STIs if taken within 24 to 72 hours after unprotected sex^[17].

If you have syphilis, your current and any recent sexual partners will also need to be tested and treated^[6]. Tell your sex partner or partners that you have syphilis so they can get treatment even if they don’t have symptoms^[17]. The healthcare provider or sexual health clinic can advise you about contacting your sexual partners, which can be done without naming you^[6].

All pregnant people should get tested for syphilis at their first prenatal checkup^[2]. Testing during pregnancy allows infections to be found and treated, preventing transmission to the baby^[21].

Complications of untreated syphilis

If syphilis is not treated, it can cause serious and potentially life-threatening problems^[2][3][6].

Without treatment, syphilis can permanently damage your heart, brain, muscles, bones, and eyes^[3]. Complications that can appear many years after being infected with syphilis include heart problems like angina, aortic aneurysm (a bulge in the body’s main artery), and heart failure; brain problems like fits (seizures), memory problems, personality changes, and dementia; nerve problems like shooting pains, pins and needles, joint pain, and gradual damage to the joints; and problems with the skin, bones, testicles, liver, and any other organ^[6].

Some of these problems may not appear for many years after being infected with syphilis^[6]. In tertiary syphilis, the disease can damage internal organs and result in death^[1].

Untreated syphilis during pregnancy can lead to stillbirth, newborn death, and babies born with syphilis^[5]. Having syphilis during pregnancy can also increase the risk of miscarriage, premature birth, and stillbirth^[6].

With early detection and treatment, syphilis can be cured before it causes irreversible damage to organs^[8]. If the disease has progressed, antibiotics can clear the bacterial infection from the body, however damage to organs may be permanent^[8].