Syphilis
Syphilis is a sexually transmitted infection caused by the bacterium Treponema pallidum subspecies pallidum. The signs and symptoms depend on the stage it presents: primary, secondary, latent or tertiary. The primary stage classically presents with a single chancre, though there may be multiple sores. In secondary syphilis, a diffuse rash occurs, which frequently involves the palms of the hands and soles of the feet. There may also be sores in the mouth or vagina. Latent syphilis has no symptoms and can last years. In tertiary syphilis, there are gummas, neurological problems, or heart symptoms. Syphilis has been known as "the great imitator", because it may cause symptoms similar to many other diseases.
Syphilis is most commonly spread through sexual activity. It may also be transmitted from mother to baby during pregnancy or at birth, resulting in congenital syphilis. Other diseases caused by Treponema bacteria include yaws, pinta, and nonvenereal endemic syphilis. These three diseases are not typically sexually transmitted. Diagnosis is usually made by using blood tests; the bacteria can also be detected using dark field microscopy. The Centers for Disease Control and Prevention recommends for all pregnant women to be tested.
The risk of sexual transmission of syphilis can be reduced by using a latex or polyurethane condom. Syphilis can be effectively treated with antibiotics. The preferred antibiotic for most cases is benzathine benzylpenicillin injected into a muscle. In those who have a severe penicillin allergy, doxycycline or tetracycline may be used. In those with neurosyphilis, intravenous benzylpenicillin or ceftriaxone is recommended. During treatment, people may develop fever, headache, and muscle pains, known as a Jarisch–Herxheimer reaction.
In 2015, about 45.4 million people had syphilis infections, of which six million were new cases. During 2015, it caused about 107,000 deaths, down from 202,000 in 1990. After decreasing dramatically with the availability of penicillin in the 1940s, rates of infection have increased since the turn of the millennium in many countries, often in combination with human immunodeficiency virus. This is believed to be partly due to unsafe drug use, increased prostitution, and decreased use of condoms.
Signs and symptoms
Syphilis can present in one of four different stages: primary, secondary, latent, and tertiary, and may also occur congenitally. There may be no symptoms. It was referred to as "the great imitator" by Sir William Osler due to its varied presentations.Primary
Primary syphilis is typically acquired by direct sexual contact with the infectious lesions of another person. Approximately 2–6 weeks after contact a skin lesion, called a chancre, appears at the site and this contains infectious bacteria. This is classically a single, firm, painless, non-itchy skin ulceration with a clean base and sharp borders approximately 0.3–3.0 cm in size. 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 being more common when coinfected with HIV. Lesions may be painful or tender, and they may occur in places other than the genitals. The most common location in women is the cervix, the penis in heterosexual men, and anally and rectally in men who have sex with men. Lymph node enlargement frequently occurs around the area of infection, occurring seven to 10 days after chancre formation. The lesion may persist for three to six weeks if left untreated.Secondary
Secondary syphilis occurs approximately four to ten 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. The rash may become maculopapular or pustular. It may form flat, broad, whitish, wart-like lesions on mucous membranes, known as condyloma latum. All of these lesions harbor bacteria and are infectious. Other symptoms may include fever, sore throat, malaise, weight loss, hair loss, and headache. Rare manifestations include liver inflammation, kidney disease, joint inflammation, periostitis, inflammation of the optic nerve, uveitis, and interstitial keratitis. The acute symptoms usually resolve after three to six weeks; about 25% of people may present with a recurrence of secondary symptoms. Many people who present with secondary syphilis do not report previously having had the classical chancre of primary syphilis.Latent
Latent syphilis is defined as having serologic proof of infection without symptoms of disease. It develops after secondary syphilis and is divided into early latent and late latent stages. Early latent syphilis is defined by the World Health Organization as less than 2 years after original infection. Early latent syphilis is infectious as up to 25% of people can develop a recurrent secondary infection. Two years after the original infection the person will enter late latent syphilis and is not as infectious as in the early phase. The latent phase of syphilis can last many years after which, without treatment, approximately 15–40% of people can develop tertiary syphilis.Tertiary
Tertiary syphilis may occur approximately 3 to 15 years after the initial infection and may be divided into three different forms: gummatous syphilis, late neurosyphilis, and cardiovascular syphilis. Without treatment, a third of infected people develop tertiary disease. People with tertiary syphilis are not infectious.Gummatous syphilis or late benign syphilis usually occurs 1 to 46 years after the initial infection, with an average of 15 years. This stage is characterized by the formation of chronic gummas, which are soft, tumor-like balls of inflammation which may vary considerably in size. They typically affect the skin, bone, and liver, but can occur anywhere.
Cardiovascular syphilis usually occurs 10–30 years after the initial infection. The most common complication is syphilitic aortitis, which may result in aortic aneurysm formation.
Neurosyphilis refers to an infection involving the central nervous system. Involvement of the central nervous system in syphilis can occur at any stage of the infection. It may occur early, being either asymptomatic or in the form of syphilitic meningitis; or late as meningovascular syphilis, manifesting as general paresis or tabes dorsalis.
Meningovascular syphilis involves inflammation of the small and medium arteries of the central nervous system. It can present between 1–10 years after the initial infection. Meningovascular syphilis is characterized by stroke, cranial nerve palsies and spinal cord inflammation. Late symptomatic neurosyphilis can develop decades after the original infection and includes 2 types; general paresis and tabes dorsalis. General paresis presents with dementia, personality changes, delusions, seizures, psychosis and depression. Tabes dorsalis is characterized by gait instability, sharp pains in the trunk and limbs, impaired positional sensation of the limbs as well as having a positive Romberg's sign. Both tabes dorsalis and general paresis may present with Argyll Robertson pupil which are pupils that constrict when the person focuses on near objects but do not constrict when exposed to bright light.
Congenital
Congenital syphilis is that which is transmitted during pregnancy or during birth. Two-thirds of syphilitic infants are born without symptoms. Common symptoms that develop over the first couple of years of life include enlargement of the liver and spleen, rash, fever, neurosyphilis, and lung inflammation. If untreated, late congenital syphilis may occur in 40%, including saddle nose deformation, Higouménakis' sign, saber shin, or Clutton's joints among others. Infection during pregnancy is also associated with miscarriage. The main dental defects seen in congenital syphilis are the peg-shaped, notched incisors known as Hutchinson's teeth and so-called mulberry molars, defective permanent molars with rounded, deformed crowns resembling a mulberry.Cause
Bacteriology
Treponema pallidum subspecies pallidum is a spiral-shaped, Gram-negative, highly mobile bacterium. Two other human diseases are caused by related Treponema pallidum subspecies, yaws and bejel, and one further caused by the very closely related Treponema carateum, pinta. Unlike subspecies pallidum, they do not cause neurological disease. Humans are the only known natural reservoir for subspecies pallidum. It is unable to survive more than a few days without a host. This is due to its small genome failing to encode the metabolic pathways necessary to make most of its macronutrients. It has a slow doubling time of greater than 30 hours. The bacterium is known for its ability to evade the immune system and its invasiveness.Transmission
Syphilis is transmitted primarily by sexual contact or during pregnancy from a mother to her baby; the bacterium is able to pass through intact mucous membranes or compromised skin. It is thus transmissible by kissing near a lesion, as well as manual, oral, vaginal, and anal sex. Approximately 30% to 60% of those exposed to primary or secondary syphilis will get the disease. Its infectivity is exemplified by the fact that an individual inoculated with only 57 organisms has a 50% chance of being infected. Most new cases in the United States occur in men who have sex with men; and in this population 20% of syphilis cases were due to oral sex alone. Syphilis can be transmitted by blood products, but the risk is low due to screening of donated blood in many countries. The risk of transmission from sharing needles appears to be limited.It is not generally possible to contract syphilis through toilet seats, daily activities, hot tubs, or sharing eating utensils or clothing. This is mainly because the bacteria die very quickly outside of the body, making transmission by objects extremely difficult.