Written by Ada’s Medical Knowledge Team
What is syphilis?
Syphilis is a sexually transmitted disease (STD) caused by bacterial infection. The medical term for syphilis that is diagnosed in the earliest stages is primary syphilis; other stages include secondary syphilis, latent syphilis and tertiary syphilis. Young adults are the group most commonly affected by syphilis. The early symptoms are small, painless sores on the genitals and enlarged lymph nodes in the neck or groin. This condition can affect many different parts of the body, so later, symptoms can differ widely from person to person. Practicing safe sex using condoms or dental dams helps to reduce the risk of catching syphilis. Antibiotics are used to treat the infection. With early and effective treatment, most people recover well.
Causes and risk factors
Syphilis is a sexually transmitted infection caused by a microorganism called Treponema pallidum. If a syphilis infection is not diagnosed and treated, it tends to cause waves of symptoms. These are called the primary, secondary and tertiary (late) stages. It can take years for syphilis to progress from the first stage to the late stage. Young adults between the ages of 15 and 24 are most commonly diagnosed. Factors that increase the chances of contracting syphilis include:
- Unprotected sex, i.e. sex without a condom or dental dam
- Sex with new partners whose STI statuses are not known
- Sharing hypodermic needles and/or injection apparatus
It is also possible for pregnant people who have contracted syphilis during pregnancy to pass on the infection to their children in utero, meaning in the womb.
If you are concerned that you may have contracted an infection, you can do a free symptom assessment using the Ada app at any time.
Stages of syphilis
Syphilis has four stages: primary, secondary, latent and tertiary.
Primary syphilis is the initial stage of infection. In this stage, a flat, painless ulcer known as a chancre develops at the point where the infection entered the body. The chancre usually appears between 10 and 90 days after infection and heals on its own after about two to twelve weeks. The chancre will heal whether or not the affected person receives treatment. However, unless the infection is treated, the affected person remains infectious even once the chancre has healed.
Secondary syphilis affects about a quarter of all people who are not treated for primary syphilis and comes two to ten weeks after primary syphilis. It has many symptoms, including a distinctive rash, which is typically most severe between three and four months after infection. Secondary syphilis can last between about one and six months. If secondary syphilis is not treated, up to 80 percent of people enter the latent phase, in which they will be asymptomatic.
Latent syphilis, early and late. In early latent syphilis, the infected person has no symptoms, but can still infect sexual partners. In late latent syphilis, the person is also asymptomatic, but is also less infectious. Because of improved testing and treatment for syphilis, latent syphilis is now quite rare.
Many people with latent syphilis are only diagnosed after routine STI screening, as they are asymptomatic. The latent phase may last for up to 25 years in some cases, although not all individuals will have a latent stage. About a third of people with latent syphilis go on to develop tertiary syphilis.
Tertiary syphilis can occur from about 3 to 15 years after the initial infection. This is when the affected individual develops complications from long-term infection. The complications can include severe neurological and cardiovascular effects. In this stage, soft, rounded, tumor-like areas of inflammation called gummas can also appear.
Neurosyphilis is a form of syphilis that affects the brain, the membranes covering the brain, and the spinal cord. Although it is most often associated with the tertiary stage of syphilis, it can occur at any stage of the condition. These days, neurosyphilis is often associated with HIV infection: approximately half of all people who develop neurosyphilis are HIV-positive. Before the invention and widespread use of antibiotic drugs, neurosyphilis was more common.
The pathogen Treponema pallidum can easily cross the placental barrier between the mother’s bloodstream and that of the infant. Mothers who have untreated syphilis run an increased risk of stillbirth or neonatal death. Untreated syphilis in a mother can lead to the death of the infant in up to 40 percent of cases. Mothers who are treated for syphilis while pregnant have a lower chance of their children being affected. This is especially true if the infection is identified and treatment given early in the pregnancy, as the Treponema organism does not cross the placental barrier until about the fifth month of pregnancy.
Babies born with a syphilis infection may be asymptomatic at first, but can develop problems later. Babies that show the symptoms of congenital syphilis within the first two years of life are said to have early congenital syphilis, while those who develop symptoms later in life have late congenital syphilis. Especially common is a cluster of symptoms known as Hutchinson’s triad, which includes deformed incisor and molar teeth, deafness and scarring of the cornea due to swelling inside the eye. Other signs include saddle nose, a condition where the bridge of the nose collapses, and Parrot’s furrows, which are radiating scars around the mouth caused by the healing-over of skin lesions.
The early symptoms of syphilis are:
- A painless sore in the genital area, mouth or buttocks
- Enlarged lymph nodes in the groin
Good to know: These symptoms usually go away within weeks and are not noticed sometimes. Some people with syphilis infection do not have the chancre, although most do.
As the condition progresses, the affected person may develop symptoms including:
- A rash
- Joint pain
- Hair loss
- Small lumps in the genital area
- Muscle aches
The later stages of syphilis develop slowly over years, and affect the heart, brain and other parts of the body. There are many possible symptoms, including:
- Shortness of breath
- Loss of coordination
- Nerve damage
Symptoms in adults
The bulk of new cases of syphilis are found among adults, and the majority of these are contracted through sexual contact. All syphilis infections among adults begin with primary syphilis – it is not possible to have secondary or tertiary syphilis without having had primary syphilis. If primary syphilis is not treated, about a quarter of all people affected will develop secondary syphilis. In some cases the condition will then progress to latent syphilis and, finally, to tertiary syphilis.
Primary syphilis is the first stage of infection and causes a chancre, which is a firm, round or oval ulcer that appears at the location where the infection entered the body. The chancre discharges a clear serum, which contains large numbers of Treponema pallidum, and is therefore very infectious. Chancres may affect the:
- Anal canal
- Mouth and lips
The chancre is typically not painful and does not discharge pus. Usually, only one chancre appears. However, in some cases, they may be painful, discharge pus or appear in groups. Lymph nodes near the chancre may also be enlarged and tender.
The chancre usually appears between ten and 90 days after the initial infection. It heals on its own in about two to twelve weeks, whether or not the affected person receives treatment. The affected person will still be infectious, unless they have received treatment.
Good to know: Because the symptoms of primary syphilis, including the chancre, can be vague, it is possible for primary syphilis to go unnoticed.
If you’re concerned that you or someone you care for may have this disorder, you can do a free symptom assessment at any time using the Ada app.
- Headaches at night
- Muscle and joint aches
- Sore throat
- Swollen lymph nodes
Less common symptoms of secondary syphilis include:
- Patchy hair loss
- Weight loss
- Meningitis, inflammation of membranes covering the brain
- Hepatitis, inflammation of the liver
- Enlarged spleen
- Inflammation of the membranes surrounding bone, known as periostitis
- Inflammation of the middle layer of the eye, known as uveitis
- Kidney problems, such as glomerulonephritis
- Cranial nerve palsies, which affect the nerves in the head and face, sometimes causing vision problems such as double vision
About 80 percent of people with untreated secondary syphilis will progress to latent syphilis, which can last for life. Some will experience a relapse of secondary syphilis symptoms within the first year of latent syphilis.
Latent syphilis is often asymptomatic. Due to effective treatments now available for primary and secondary syphilis, it is rarely seen nowadays.
Tertiary syphilis has a number of symptoms. Tertiary syphilis is a complex stage, because the cardiovascular and neurological effects of the condition manifest in many different ways.
- Aortic aneurysm, in which the wall of the aorta weakens and forms a bulge, which can leak
- Aortitis, in which the aorta is inflamed
- Angina, a painful condition in which blood flow to the heart muscle is reduced
- Tabes dorsalis
- General paresis of the insane
- Meningeal syphilis
- Meningovascular syphilis
For more information on these conditions, see below.
Gummae, or gummatous lesions, are large soft benign tumors that can form in the skin anywhere on the body and also in the mouth, organs, bones, testes and upper respiratory tract. They are most commonly found on the lower leg. Gummae tend to have a somewhat rubbery texture with a centre of dead tissue. Occasionally, gummae may ulcerate and destroy tissue. Gummae are an uncommon manifestation of tertiary syphilis.
Congenital syphilis symptoms in children
Congenital syphilis may remain asymptomatic throughout life, but in many cases symptoms do appear. It is rare for symptoms to be apparent at the time of birth: over 60% of babies with congenital syphilis only show symptoms later in life.
In early congenital syphilis, which appears within the first two years of life, symptoms can include:
- Rash on the infant’s palms and soles
- Skin lesions around the nose and mouth
- Skin lesions in the diaper area
- Enlarged lymph nodes
- An enlarged spleen and liver
- A runny nose, known as rhinitis, with bloody mucus
- Failure to thrive
- Hydrocephalus, a buildup of fluid on the brain
- Acute meningitis
- Intellectual disabilities
Good to know: The nasal discharge of infants with syphilis-related rhinitis contains large numbers of Treponema pallidum, and is therefore infectious.
In late congenital syphilis, symptoms can include:
- Gumma and gumma-related ulcers affecting the nose and mouth
- Central nervous system abnormalities such as hydrocephalus, seizures, intellectual disability, loss of sight, and problems with movement
- Loss of sight
- Loss of hearing
- Dental deformities
- Abnormally swollen knee joints, known as Clutton’s joints, and shin bones, known as saber shins, a condition in which the shinbone becomes deformed due to softening
The symptoms of syphilis transmitted by sexual activity are rare in children, but in the uncommon cases where they do occur, they are the same as those in adults.
Rash and sores in syphilis
In primary syphilis, the most distinctive symptom of the infection is the chancre, a small, flat and painless ulcer that develops at the site of infection. This chancre may be pink and is usually round or oval in shape.
In secondary syphilis, a rash is one of the most distinctive symptoms. This rash does not have a uniform appearance, but may take on several different forms, including:
A red and/or pink skin rash, which turns reddish-brown. It may be faint. This rash can affect the soles, the palms and the face. This rash may occasionally spread to cover the entire body, but it does not itch.
Flat, soft growths, known as condylomata lata, which occur around the vagina and/or anus, or other warm, moist areas of the body and mucus membranes. These are pink or grey, not painful or itchy, and often disappear spontaneously.
White patches on tongue and/or roof of the mouth.
A rash is not a common feature of other stages of syphilis, but in tertiary syphilis, gummatous lesions affecting the skin may develop. If you are concerned that you might have contracted syphilis, you can check your symptoms using the free Ada app.
Symptoms of neurosyphilis
- Acute syphilitic meningitis
- Meningovascular syphilis
- General paresis (of the insane)
- Tabes dorsalis
Good to know: Neurosyphilis can also be asymptomatic.
Acute syphilitic meningitis, also known as meningeal syphilis, presents much the same as viral meningitis and bacterial meningitis do, with symptoms such as a stiff neck, a headache, nausea and vomiting. In some cases, the affected person may lose vision or hearing. This complication can occur within a few months of the initial syphilis infection.
Meningovascular syphilis usually occurs about seven years after the affected person first contracts syphilis. Symptoms include headache, stiff neck, nausea, vomiting and stroke. Stroke typically comes last, while headache, stiff neck, nausea and vomiting are prodromal symptoms, meaning they indicate that something more serious is coming. Meningovascular syphilis occurs when the blood vessels in the subarachnoid space, i.e. between the meningeal membranes, become inflamed, which can lead to clotting and blockages and therefore to stroke, even in younger people.
General paresis (of the insane) (GPI) typically occurs two to three decades after the initial infection and develops slowly. Symptoms of general paresis may initially be more obvious to close associates, such as friends, family and colleagues of the affected person than they are to the affected person. Symptoms of GPI may include:
- Memory problems
- Apathy and withdrawal
- Loss of interest in work or personal affairs
- Mood changes
- Personality changes
GPI can also manifest as schizophrenia or other cognitive disorders, but most commonly presents as presenile dementia. Symptoms of presenile dementia include depression, confusion, memory loss and impairment of judgement.
Learn more about Signs of Dementia
Tabes dorsalis is a condition resulting from a slow, progressive degeneration of tissues around the spinal cord. It can take anything from about five to 50 years for tabes dorsalis to develop. Symptoms of tabes dorsalis may include:
- Loss of ability to sense pain, vibration and position
- Worsening ataxia, a condition that can result from loss of a sense of the relative position of body parts and causes changes in movement and function
- Loss of reflexes
- Loss of bladder control
- Loss of sexual function
- Sharp, excruciating, sudden stabs of pain in the abdomen and limbs, known as lancinating pains
- Nausea and vomiting
- Severe pain around the upper abdominal region
Good to know: Ataxia affects gait, speech and eye movements, as well as voluntary muscle movements and coordination. As ataxia progresses, the affected person may begin to speak indistinctly or have difficulty speaking, develop a gait in which the forward foot slaps the ground rather than being steadily placed, and be unable to control the direction of their gaze.
The diagnosis is usually made based on the symptoms, a physical examination and a blood test for syphilis antibodies, which are proteins that fight the infection. Many people are diagnosed by screening, i.e. testing people at risk without symptoms, because syphilis can cause no symptoms, or very unusual symptoms. If there is an ulcer present, a sample of fluid from the ulcer may be taken and investigated for signs of the bacteria.
Laboratory tests for syphilis
Testing for syphilis is usually done on blood samples. In some cases, where neurological effects are being seen or neurosyphilis is suspected, a lumbar puncture may be carried out to obtain a sample of cerebrospinal fluid (CSF), which is then tested.
The two main types of laboratory tests for syphilis are nontreponemal tests and treponemal tests.
Nontreponemal tests test for antigens produced by a syphilis infection, not specifically for the Treponema pallidum microorganism itself. This sort of test is used for syphilis screening.
While this sort of test is widely used, it can result in false-positive results if the tested person is pregnant, uses intravenous drugs, or has other infections or autoimmune disorders. Furthermore, if the person being tested is in very early primary syphilis or late latent syphilis, they may get a false-negative result.
Generally, people who test positive using a nontreponemal test will need a follow-up treponemal test to confirm the diagnosis.
Treponemal tests detect antibodies that are specific to Treponema pallidum. These tests were initially more expensive and difficult to carry out than nontreponemal tests and were therefore not used for screening, but are used to confirm a diagnosis. These days, it is possible to use them for screening, known as reverse screening. However, treponemal tests cannot tell whether a syphilis infection is active or latent and should therefore be followed by a nontreponemal test, which can tell the difference.
Previously, the best way to test for syphilis was to use a process known as darkfield microscopy to see whether there were Treponema pallidum microorganisms in a sample of fluid taken from a chancre. This is no longer the best method, as it is not suitable for asymptomatic cases, as well as being expensive, difficult and requiring highly-trained staff. It is no longer often used in clinical practice. While rapid tests for syphilis are being developed and may have limited availability in the U.S.A., they are not yet thought to be as reliable as laboratory-based tests.
Good to know: Home test kits are available, but are not recommended as they are not considered to be reliable.
Treatment and management
Syphilis is treated with antibiotics. Follow-up tests are usually done to test if the infection has been completely treated. Benzathine penicillin is the first-line treatment of choice for all stages of syphilis. Other options, especially if the affected person is allergic to penicillin, are doxycycline and ceftriaxone. Benzathine penicillin is usually administered via an intramuscular injection, while doxycycline and ceftriaxone are usually administered either intravenously or intramuscularly. All three are administered in large doses, over one or several consecutive days. Benzathine penicillin can be administered in several different dosage patterns, depending on the stage of syphilis being treated.
Although it is not always necessary for someone receiving this kind of treatment to be hospitalized, the size of the dosage and the method of delivery usually means that treatment is done under the direct supervision of a doctor or nurse. This supervision also improves the chances that the affected person will complete the course of treatment, as receiving a single dose given by a doctor means that there is no possibility of the affected person missing a dose when they go home.
After treatment, improvement is usually swift. However, an uncomfortable condition known as the Jarisch-Herxheimer reaction may occur shortly after receiving antibiotics, as dying Treponema pallidum organisms release toxins into the bloodstream. This condition is short-term and is usually not dangerous. Symptoms include:
- Muscle pain
- A rapid heartbeat
If this reaction occurs, antibiotics will **not be discontinued, ** but a corticosteroid such as prednisone or cortisone may be prescribed as treatment.
If treated correctly with antibiotic therapy, primary and secondary syphilis have an excellent prognosis. However, because tertiary syphilis usually occurs after years of latent infection, the overall prognosis of syphilis varies. Untreated tertiary syphilis can be fatal, especially if it has involved the cardiovascular system. People affected by gummatous tertiary syphilis, however, often see improvement after treatment.
Newborn babies affected by congenital syphilis have variable outcomes, but fatality can occur.
People affected by neurosyphilis have different outcomes. People who have asymptomatic neurosyphilis and meningeal neurosyphilis usually return to normal health. People with meningovascular syphilis may improve, but, especially if a stroke has occurred, seldom return to normal health.
General paresis of the insane and tabes dorsalis have lifelong effects: while the affected person may improve, they will not regain lost functions. The earlier the disorder is identified and treated, the better the prognosis.
Practicing safe sex can prevent new syphilis infections. Barrier methods such as condoms and dental dams are, if used correctly and with appropriate lubricants, effective in preventing syphilis being passed from one partner to another.
Pregnant women are usually screened, i.e. tested without symptoms for syphilis to prevent passing the bacteria to their child.
Syphilis and HIV
The rates of syphilis infection in the U.S.A. decreased after the 1970s, largely due to improved treatment methods and sexual health education. However, since the 2000s, rates of syphilis infection have increased worldwide. In the U.K and the U.S.A., new cases of syphilis infection are concentrated among men who have sex with men (MSM).
In the U.S., about half of MSM with syphilis are also living with HIV. Sexual behaviors that increase the chances of acquiring an STI such as syphilis also increase the risk of contracting HIV. People who already have an STI that creates breaks in the skin, such as syphilis, are several times more likely to acquire HIV if they are exposed to the virus.
While being HIV-positive does not always change the course of a syphilis infection, there is some evidence that syphilis can progress from stage to stage more quickly in people with HIV. There is also some evidence that, because HIV hinders the immune system’s responses to a syphilis infection, this leads to more severe symptoms and less effective treatment.
Q: Is syphilis contagious?
A: Yes. Syphilis can be passed from person to person. Most people contract syphilis through sexual contact with an infected person, but it is also possible for mothers with syphilis to pass the infection on to their children during pregnancy. Rarely, people who share injection apparatus or who are pricked by a contaminated hypodermic needle may contract syphilis if the needle has been used by someone with syphilis.
- Any asymptomatic person who is concerned that they may have been exposed to syphilis by a sexual or intimate partner
- Anyone showing any symptoms of any stage of syphilis
- All pregnant women or women who are planning to become pregnant
- Anyone who has recently had unprotected sex with a new partner whose STI status they do not know
- Anyone who has recently had unprotected sex with multiple partners
- Anyone who has another STI, such as chlamydia or gonorrhea, or whose partner has disclosed that they have an STI
- Anyone who is HIV-positive
- Men who have sex with men
- Anyone who has previously had syphilis
Q: What should I do if I think I have syphilis?
A: Anyone who suspects that they may have syphilis should go to a doctor, clinic or specialized sexual health clinic and ask to be tested for syphilis.
Q: Should people who do not show symptoms but think they may have been exposed to syphilis seek testing for syphilis?
A: Yes. It is possible for syphilis to be asymptomatic. If you think you have been exposed to syphilis by an intimate or sexual partner, but do not show symptoms, you should seek testing. It is especially important to seek testing if you may fall pregnant, engaged in unprotected sex, and/or have multiple sexual partners.
Q: Are people who have unprotected sex at risk of contracting syphilis?
A: Yes. Syphilis is spread by sexual activity, such as oral sex, anal sex and vaginal sex, as well as any other genital contact and sharing of sex toys. Syphilis is transmitted by direct contact with a chancre during sex. Preventing contact with an infectious chancre, for example by using a condom or dental dam, cuts down on the risk of the infection being transmitted.
Q: Can one contract syphilis through administering first aid to someone with syphilis?
A: Syphilis is a blood-borne pathogen, and it is possible that contact with the blood of someone who has syphilis, as might happen while administering first aid, might pass on the infection. The primary risk to first-aiders and emergency medical technicians, however, comes from injury with a contaminated needle.
Q: Can one contract syphilis through sharing sex toys?
A: Yes, if one’s sexual partner has syphilis, and sex toys are shared between partners. The risk of this can be reduced by:
Using condoms on sex toys, with a new condom for each partner.
Cleaning the toys thoroughly between uses, using soap and water or a dedicated toy-cleaning solution.
Using the correct type of lubricant, as using the incorrect type will cause damage to the toy’s surface, making it more difficult to clean.
Other names for syphilis infection
- Primary, secondary or tertiary syphilis
- Lues primary state
- Primary lues venerea
- Primary syphilis infection
Centers for Disease Control and Prevention. "Syphilis & MSM (Men Who Have Sex With Men) - CDC Fact Sheet". 26 September 2017. Accessed 12 December 2018. ↩