Syphilis, Acquired

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  • Lues, Acquired
  • Venereal Disease

Disorder Subdivisions

  • None

General Discussion

Syphilis is a chronic infectious disease caused by the bacterium (microorganism) treponema pallidum. It is transmitted by direct contact with an infected lesion, usually through sexual intercourse. When untreated, syphilis progresses through primary, secondary and latent stages. The early stages of syphilis may not have any detectable symptoms. In some cases, symptoms can remain dormant for years. Eventually any tissue or vascular organ in the body may be affected.

Syphilis may also be acquired by the fetus in the uterus (congenital syphilis). Syphilis, especially when detected early, may be cured with appropriate treatment.


Untreated syphilis progresses through primary and secondary stages (which are infectious), and may end without further symptoms or continue to progress into a latent stage that may last for years.

Primary syphilis is characterized by lesions (chancres) of the skin, anus, vagina or moist surface of the mouth. These lesions present themselves from 10 to 90 days after an individual has been exposed to the organism and are found at the sight of contact with the infected person. The lesions are usually painless and start as small, solid elevations (papules) of the skin that gradually develop into raised, firm ulcers with a slight yellow discharge. When untreated, these lesions heal within four to six weeks and may leave scarring.

Secondary syphilis usually presents itself within two weeks to six months after the appearance of the primary lesions. This stage of the disorder is characterized by lesions of the skin and mucous membranes that may be pink or coppery in color, widespread, symmetrical, and follow the lines of skin cleavage. The skin lesions of secondary syphilis are infectious and most often found on the genitalia, palms, and soles of the feet. Symptoms such as loss of appetite, sore throat, headache, low-grade fever, muscle aches, nasal discharge, and swollen lymph nodes may occur. There is a relapse in 25 percent of the untreated cases, occurring most often in the first year. Secondary syphilis usually lasts two to six weeks and some of the lesions may leave scarring.

Latent syphilis occurs when primary and secondary syphilis have gone untreated. There are no noticeable symptoms, and the diagnosis can only be made through laboratory tests. Affected individuals are not contagious during this stage. However, they may relapse during the first two to four years of infection, and infectious secondary syphilis lesions may reappear. In about one third of the cases the disease spontaneously cures itself. Another third will remain infected but show no signs of the disease (asymptomatic). The final third will eventually develop late syphilis.

Late syphilis, also known as tertiary syphilis, is not contagious and usually progresses slowly. Benign (non-contagious) tumors may develop on any part of the body. These tumors usually involve the skin and bones. Heart disease (cardiovascular problems), seizures, mental illness, personality changes, impotence, bladder dysfunction, and eye problems such as degeneration of the optic nerve of the eye (optic atrophy) and the development of Argyll Robertson pupils (pupils that fail to react to light but still react to distance) may also be present with late syphilis. Dementia and blindness may eventually result.

In approximately three to seven percent of cases, affected individuals may develop neurosyphilis during the early stages of syphilis. Neurosyphilis occurs when the syphilis bacteria spread to the central nervous system. Affected individuals may not develop any associated symptoms. In some cases, individuals will experience seizures, headaches, fevers, stiff neck, dementia, and behavioral abnormalities.


Syphilis is caused by a bacterium (microorganism) known as treponema pallidum and acquired through sexual contact with an infected person. On rare occasions, health workers have become infected while examining affected individuals with infectious lesions. It may also be acquired by kissing someone with oral infectious lesions. Infected mothers can transmit syphilis to the fetus in the womb, a condition known as congenital syphilis. (For more information on this disorder choose "congenital syphilis" as your search term in the Rare Disease Database.)

Affected Populations

There are about 80,000 cases of syphilis reported each year in the United States. The highest rate of syphilis is among 20 to 24 year old men and women. Syphilis is more common in the southern states of the United States. It is more common among persons who have sexual contact with numerous partners.The male to female ratio of syphilis is 3:1. In recent years, the rates of syphilis have declined in the United States. Syphilis occurs with higher rates in developing countries, although developed countries experience outbreaks.

In 1998, the incidence of syphilis was 2.6 cases per 100,000 people in the United States, a lower rate than in 1997 when there were 3.2 cases per 100,000 people. The US Centers for Disease Control and Prevention (CDC) is working toward eliminating syphilis and plans to reduce the incidence of syphilis to fewer than 1,000 cases in the United States by the year 2005. In 2002, the CDC reported that the number of cases of syphilis in the United States rose from 5, 979 in 2000 to 6,103 in 2001, the first increase since 1990.

Standard Therapies


A diagnosis of syphilis, which is often difficult because of mild or absent symptoms in early states, is made based upon a thorough clinical evaluation, a detailed patient history, and identification of characteristic symptoms. Blood tests may be used to confirm a diagnosis of syphilis, but may be difficult to interpret and often give false negative results. A physician may also obtain a small sample of tissue by scraping an ulcer or rash for microscopic study in order to determine the presence of the syphilis bacteria.


Antibiotics are used to treat acquired syphilis. Penicillin is the treatment used most often. Some individuals do not respond to therapy with penicillin, and periodic blood tests to confirm the absence of syphilis is recommended.

In some cases, other antibiotics such as tetracycline or erythromycin may be used. Preventative treatment should be given to anyone who has been in sexual contact with an infected person within 90 days. It is very important that an affected individual's history (especially sexual) be taken, and a battery of tests performed, in order to determine the stage of syphilis present.

Investigational Therapies

Information on current clinical trials is posted on the Internet at All studies receiving U.S. Government funding, and some supported by private industry, are posted on this government web site.

For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:

Tollfree: (800) 411-1222

TTY: (866) 411-1010


For information about clinical trials sponsored by private sources, contact:



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Odonnell JA, Emery CL. Neurosphylis: a current review. Curr Infect Dis Rep. 2005;7:277-84.

Marra CM. Neurosyphilis. Curr Neurol Neuro Rep. 2004;4:435-40.

Mitka M. US effort to eliminate syphilis moving forward. JAMA. 2000;283:1555-56.

Gruber F, et al. Treatment of early syphilis with azithromycin. J Chemother. 2000;12:240-43.

Vargas AP, et al. Dementia by neurosyphilis: clinical and neuropsychological follow-up of a patient. Arq Neuropsiquiatr. 2000;58:578-82.

Phan TG, et al. Intractable epilepsy as the initial manifestation of neurosyphilis. Epilepsia. 1999;40:1309-11.

Rolfs RT, et al. Treatment of early syphilis. N Engl J Med. 1997;3371697-98.

Dorfman DH, et al. Congenital syphilis presenting in infants after the newborn period. N Engl J Med. 1990;323:1299-302.


National Institute of Allergy and Infectious Diseases. Syphilis. November 2002. Available at: Accessed On: August 11, 2005.

Pulver B. Syphilis. eMedicine Journal. 2004;3:10pp. Available at: Accessed On: August 11, 2005.


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