Syphilis is a sexually transmitted infection (STI) caused by the spirochete bacterium Treponema pallidum (Pic. 1) transmitted through sex or vertically during pregnancy (congenital syphilis). It is characterized by periods of activity and latency, disseminated systemic involvement (affects a number of organs and tissues), and progression to acute complications in patients that remain untreated or have been inadequately treated.

Syphilis can present with signs and symptoms (this is called primary or secondary syphilis) or without signs and symptoms (this is called early latent syphilis). The primary stage classically presents itself with a single chancre (a firm, painless, non-itchy skin ulceration; Pic. 2). Secondary syphilis shows itself with a diffuse rash that frequently involves the palms of the hands (Pic. 3) and soles of the feet. Latent syphilis displays little to no symptoms, and neurosyphilis (tertiary) can result in neurological and cardiac symptoms because the syphilis has been undiagnosed or untreated for many years. All of these stages are infectious and can be passed on to sexual partners for up to two years if the person is not treated. Not everyone who has syphilis has signs of infection, so a person can have it and pass it on without knowing.

Syphilis is transmitted primarily by sexual contact or during pregnancy from a mother to her fetus. The spirochete is able to pass through intact mucous membranes or compromised skin. Therefore, it is transmissible by kissing, or oral, vaginal, and anal sex. Approximately 30 to 60 percent of those exposed to primary or secondary syphilis will get the disease. It can be transmitted via blood products, but, many countries test for it, and thus the risk is low. The risk of transmission from sharing needles appears limited. Syphilis cannot be contracted through toilet seats, daily activities, hot tubs, or sharing eating utensils or clothing.

A simple blood test is usually used to diagnose syphilis. If a person has an ulcer or sore this can also be tested for syphilis with a swab. There is a short period after exposure to syphilis when the tests may not pick up the early stages of infection and repeat tests may be necessary. If a person has contracted syphilis they will test positive by blood tests three months after infection, and usually much earlier. Sometimes people with syphilis have other sexually transmissible infections. So tests for other STIs should be done at the same time.

Syphilis can be effectively treated with antibiotics, specifically the preferred intramuscular penicillin G (given intravenously for neurosyphilis), or else ceftriaxone, and in those who have a severe penicillin allergy, oral doxycycline or azithromycin. It is important to have regular blood tests three to six months after syphilis treatment to check that the treatment has worked.

Even after treatment, some of the blood tests will remain positive for syphilis. This does not mean that the person is still infected. It just shows that they have had syphilis in the past. It is important that all sexual partners get treated to stop re-infection and to prevent the infection spreading in the community. 

Associated diseases

  • sexually transmitted diseases (STI)
  • HIV infection
  • cardiovascular diseases
  • pelvic inflammatory disease (PID)


If the infection is not treated, the signs and symptoms will go away, although some of them may come and go for up to a year. However, the syphilis infection still remains in the body and people can pass syphilis onto their sexual partners during this time for up to two years.

If a pregnant woman has untreated syphilis, the infection can pass, via the placenta, to her unborn baby. This can seriously affect the baby. Infection can pass from mother to baby for a much longer period than for sexual partners. It is believed to be a risk for any pregnancy for up to eight years after initial infection if that infection was not treated. Untreated syphilis in pregnancy leads to adverse outcomes among more than half of the women with active disease, including early fetal loss, stillbirth, prematurity, low birth weight, neonatal and infant death, and congenital disease among newborn babies.

If late latent syphilis is not treated, over time (which may be many years), the syphilis infection can affect different parts of the body. It can cause problems with nerves (neurosyphilis), the brain and the large vessels near the heart.


Neurosyphilis occurs when syphilis is left untreated from many years. The brain and spinal cord become infected with the syphilis bacterium, Treponema pallidum, during the secondary stage of infection and can remain latent for 10 to 20 years after the initial infection. Eventually, this infection begins to damage the tissues of the brain and spinal cord, resulting in neurosyphilis. Neurosyphilis is characterized by neurological and psychiatric symptoms, such as confusion, blindness, abnormal gait and dementia. Left untreated, neurosyphilis symptoms will worsen over time and can lead to death. Treatment for neurosyphilis is the same as any other stage of syphilis, requiring only a short course of penicillin.

Risk factors

  • engage in unprotected sex
  • have sex with multiple partners
  • being a man who has sex with men
  • being infected with HIV, the virus that causes AIDS 
  • babies of mothers who have not had adequate antenatal care, including syphilis testing during pregnancy

Nowadays, sexually transmitted diseases are one of the most common public health issues. Among its consequences are the possibility of transmission from mother to baby – which may cause miscarriages and congenital disease, male and female infertility, and the increase of HIV infection risk.

Male infertility

Although a direct toxic effect of syphilis on male fertility has not been reported in the literature, complications of syphilis can affect fertility. Syphilis of the testicles confined to the epididymis (the coiled tube on the back of the testicle) has the potential to cause obstruction of the epididymis (syphilitic epididymitis). Chronic inflammation of the intima or inner lining of an artery) that results in an occlusion of the lumen of the artery (obliterative endarteritis) and interstitial (surrounding the body structures) inflammation can occur in congenital or tertiary syphilis and lead to small, fibrotic testes as a sequel to inflammation or degeneration. Long-term syphilitics infection (terciary) is usually associated with gummatous lesions (Pic. 4). Gummas have a firm, necrotic center surrounded by inflamed tissue and cause destruction of the local tissue and, if occurring in the testicles, may have an impact on testicular function and fertility. There can also be an indirect effect: tabes dorsalis, a form of neurosyphilis characterized with slowly progressive degeneration of the spinal cord, can cause erectile dysfunction.

Female infertility

Syphilis can cause pelvic inflammatory diseases, which can lead to endometrial damage. Furthermore, this damage results in repeated repair and regeneration processes, which may thicken the endometrial lining and lead to abnormal endometrial functioning and reduced endometrial receptivity (the ability to perceive the embryo), resulting in infertility. 

Much more common than the complications of syphilis are the devastating effects of untreated infectious syphilis on pregnancy and the newborn. Spontaneous abortion and still birth occur in 50% of pregnancies, with mortality of infected infants being over 10%. Before proceeding with any form of fertility treatment, it is imperative that both partners should be tested for syphilis and treated when indicated.

Use of condoms and dissemination of information to the population comprise some measures to control syphilis adopted by health program organizers.

The safest ways to protect against syphilis are to:

  • Always use condoms and water based lubricant. Condoms are the best way of protecting against syphilis and other STIs. However, condom use does not completely eliminate the risk.
  • Avoid having sex with someone who has a visible ulcer or sore on their genitals and/or mouth.
  • Have a relationship where neither partner has other sexual partners.
  • Have fewer sexual partners.
  • Have regular STI check-ups, especially if partners change. 
  • If diagnosed with an STI, complete the recommended course of treatment.

All women should have a syphilis test in the first 12 weeks of pregnancy or at the first antenatal visit. The earlier syphilis is treated during the pregnancy, the lower the risk of the baby being affected by syphilis.

There is no vaccine for syphilis. Previous infection and previous treatment do not protect a person from getting syphilis again.

Primary syphilis

Primary syphilis is typically acquired by direct sexual contact with the infectious lesions of another person. Approximately three to 90 days after the initial exposure (average 21 days) a skin lesion, called a chancre (Pic. 5), appears at the point of contact. This chancre is classically a single, firm, painless, non-itchy skin ulceration with a clean base and sharp borders between 0.3 and 3.0 cm in size. However, the lesion may take on almost any form. In the classic form, it evolves from a macule to a papule and finally to an erosion or ulcer. Occasionally, multiple lesions may be present, with multiple lesions more common when co-infected with HIV. Lesions may be painful or tender (in 30 percent of those infected), and they may occur outside of the genitals (2 to 7 percent). The lesion may persist for three to six weeks without treatment.

Secondary syphilis

Secondary syphilis occurs approximately four to 10 weeks after the primary infection. While secondary disease is known for the many different ways it can manifest, symptoms most commonly involve the skin, mucous membranes, and lymph nodes. There may be a symmetrical, reddish-pink, non-itchy rash on the trunk and extremities, including the palms and soles of the feet. The rash may become maculopapular (a flat or raised red bump on the skin) or pustular (containing vesicles with purulent material). It may form flat, broad, whitish, wart-like lesions known as condyloma latum on mucous membranes. All of these lesions harbor bacteria and are infectious.

Early latent syphilis

This means that the person does not have any signs or symptoms but is infectious. The only way they would know they had syphilis is to have a blood test.

Late latent syphilis

This means the person is not infectious. The only way the person would know they have syphilis is to have a blood test.
Other symptoms may include fever, sore throat, malaise, weight loss, hair loss, and headache. Rare manifestations include hepatitis, kidney disease, arthritis, periostitis (inflammation of the periosteum, a layer of connective tissue that surrounds bone), optic neuritis (inflammation of the optic nerve), uveitis (inflammation of the uvea, the middle layer of the eye), and interstitial keratitis (corneal scarring due to chronic inflammation of the corneal stroma). The acute symptoms usually resolve after three to six weeks; however, about 25 percent of people may experience a recurrence of secondary symptoms.

Avoiding transmission of the disease consists of detecting and initiating early and appropriate treatment of the patient and his/her partner(s). In detecting cases, the use of the rapid test in partners of patients or pregnant women may be important. Adequate treatment consists of using penicillin as a first choice and at the appropriate doses. In special situations, such as a localized increase in cases, prophylactic treatment may be considered. Surgical therapy is not used to treat syphilis.


Penicilin injections

Syphilis is usually managed with penicillin (benzathine penicillin G) injections into buttock or thigh muscle which treat the infection in five days. This is the most effective treatment for syphilis, as it is more effective and cheaper than oral antibiotics. Doxycycline and tetracycline are alternative choices for those allergic to penicillin; due to the risk of birth defects these are not recommended for pregnant women. Resistance to macrolides, rifampin, and clindamycin is often present. Ceftriaxone, a third-generation cephalosporin antibiotic, may be as effective as penicillin-based treatment. It is recommended that a treated person avoid sex until the sores are healed. 

For neurosyphilis, due to the poor penetration of penicillin G into the central nervous system, those affected are recommended to be given large doses of intravenous penicillin for a minimum of 10 days. If a person is allergic, ceftriaxone may be used or penicillin desensitization attempted. Other late presentations may be treated with once-weekly intramuscular penicillin G for three weeks. If allergic, as in the case of early disease, doxycycline or tetracycline may be used, albeit for a longer duration. Treatment at this stage limits further progression but has only slight effect on damage which has already occurred.

A person with syphilis should abstain from sexual activity until five days after completing their course of treatment and all signs and symptoms of syphilis have cleared. 

In special situations, such as a localized increase in cases, prophylactic treatment (used to prevent a disease from occurring) may be considered.

Surgical therapy

Not used.

Assisted reproduction techniques (ART) patients should receive routine syphilis serology testing. If the results are positive, the couples should receive standard anti-syphilis treatment, and be informed of the unfavorable in vitro fertilization (IVF) pregnancy outcome due to the infection. If the embryos require cryopreservation (preserved by cooling to very low temperatures), a closed loading device should be used to avoid iatrogenic cross-infection in the hospital (induced inadvertently by a physician or surgeon or by medical treatment or diagnostic procedures).

In vitro fertilization may be the last resort for couples attempting to overcome infertility. A positive history of syphilis infection can reduce the clinical pregnancy rate following IVF/ICSI. This reduction in the clinical pregnancy rate involves a variety of factors, including endometrial thickness, the number of mature oocytes, the number of fertilized, normally cleaved oocytes, and the implantation rate. However, the mechanisms underlying the effects of syphilis on IVF success are currently unclear. One previous report on the effects of syphilis on IVF outcome has shown lower fertilization and implantation rates due to infection of the male parent with latent syphilis compared with the rates in those without syphilis infection.

Infertile couples may also resort to egg donation or embryo donation when the female partner cannot have genetic children because her own eggs cannot generate a viable pregnancy. Surrogacy via a gestational carrier is also an option when a patient's medical condition prevents a safe pregnancy, when a patient has ovaries but no uterus due to congenital absence or previous surgical removal, and where a patient has no ovaries and is also unable to carry a pregnancy to full term.

Find more about related issues


Assisted reproductive technology ―sourced from Fertilitypedia licensed under CC BY-SA 4.0
Syphilis: diagnosis, treatment and control ―by Avelleira and Bottino licensed under CC BY-NC 4.0
Syphilis ―sourced from Queensland Government licensed under CC BY 3.0 AU
Syphilis ―sourced from Boundless licensed under CC BY-SA 4.0
Syphilis ―sourced from Wikipedia licensed under CC BY-SA 3.0
Approach in sexually transmitted diseases ―by Belda Junior et al. licensed under CC BY-NC 4.0
Gumma (pathology) ―sourced from Wikipedia licensed under CC BY-SA 3.0
Syphilis (1895) (14783642045) ―by Cooper and Cotterell licensed under CC BY-SA 3.0
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