Syphilis Tests

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Also known as: Venereal Disease Research Laboratory; VDRL; Rapid Plasma Reagin; RPR; Fluorescent Treponemal Antibody Absorption Test; FTA-ABS; Treponema pallidum Particle Agglutination Assay; TPPA; Microhemagglutination Assay; MHA-TP; Darkfield Microscopy; Automated Immunoassays for Syphilis Antibodies; Treponema pallidum by PCR
Formal name: Syphilis Detection Tests

At a Glance

Why Get Tested?

To screen for or diagnose an infection with the bacterium Treponema pallidum, which causes the sexually transmitted disease (STD) syphilis

When to Get Tested?

When you have symptoms of a syphilis infection or are at risk of being infected with syphilis, such as when you have another STD or HIV, have a sexual partner diagnosed with syphilis, or have engaged in high-risk sexual activity; when you are pregnant

Sample Required?

A blood sample drawn from a vein in your arm, a scraping from a chancre in the affected area, or cerebrospinal fluid taken via a spinal tap, depending on your clinical presentation

Test Preparation Needed?

None

The Test Sample

What is being tested?

Syphilis is an infection caused by the bacteria Treponema pallidum that is most often spread by sexual contact, such as through direct contact with a syphilis sore (chancre), a firm, raised, painless sore. The most common syphilis tests detect antibodies in the blood that are produced in response to a T. pallidum infection. Some methods that are used less commonly directly detect the bacteria or its genetic material (DNA).

Syphilis is easily treated but can cause severe health problems if left untreated. An infected mother can also pass the disease to her unborn child, with serious and potentially fatal consequences for the baby. (See Common Questions #3)

There are several possible stages with syphilis:

  • Primary syphilis—the primary stage begins about 2-3 weeks after being infected. One or more chancres appear, usually on the part of the body exposed to the sexual partner's chancre, such as on the penis or vagina. However, the chancre is usually painless and may go unnoticed, especially if it is in the rectum or on the cervix, and disappears within 4-6 weeks, healing regardless of whether the infected person is treated or not.
  • Secondary syphilis—if primary syphilis is left untreated, secondary syphilis may occur from 6 weeks to 6 months after the chancre first appears. It is marked by a skin rash that often is rough, red, and spotted, appearing frequently on the palms of the hands and the bottoms of the feet (an unusual place for most other causes of rashes) and that usually does not itch. There may be other symptoms as well, such as fever, fatigue, swollen lymph nodes ("glands"), sore throat, and body aches.
  • Late, tertiary syphilis—if untreated, secondary syphilis may continue into a latent stage, during which an infected person has no symptoms but continues to have the infection, and this stage can last for years. If still untreated, about 15% of people will develop the complications of late, or tertiary, syphilis. In these cases, the bacteria can damage the heart, eyes, brain, nervous system, bones, joints, or almost any other part of the body. When the central nervous system is affected, it is called neurosyphilis. Tertiary syphilis can last for years, with the final stage leading to mental illness, blindness, other neurological problems, heart disease, and death.

Syphilis is most infectious during the primary and secondary stages. In 2011, about one-third of over 46,000 new cases of syphilis reported to the Centers for Disease Control and Prevention (CDC) were primary or secondary stage syphilis. Seventy-two percent of these cases were among men who have sex with men.

Syphilis can be treated with antibiotics, preferably penicillin. Newly acquired infections can be cured easily; however, longer treatment may be needed for someone who has been infected for more than a year.

How is the sample collected for testing?

Depending on the stage of disease and test method used, different samples are needed:

  • Most often, blood is drawn from a vein in the arm to test for antibodies.
  • If a syphilis sore is present, a health care provider may take a scraping from the chancre on the affected area, such as the cervix, penis, anus, or throat.
  • If someone has late or latent stages of the disease with suspected brain involvement (neurosyphilis), the doctor will perform a spinal tap to check the cerebrospinal fluid (CSF) for infection.

NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.

Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed.

The Test

Common Questions

Ask a Laboratory Scientist

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This was not an easy step for us to take, as the volunteers on the response team are dedicated to the work they do and are often inspired by the help they can provide. We are actively seeking to expand our capability so that we can again accept and answer all user questions. We will accept and respond to the same limited number of questions tomorrow, but expect to resume the service, 24/7, as soon as possible.

Article Sources

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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.

Sources Used in Current Review

Centers for Disease Control and Prevention. Syphilis - CDC Fact Sheet. Available online at http://www.cdc.gov/std/syphilis/stdfact-syphilis.htm through http://www.cdc.gov. Last updated December 13, 2012. Accessed January 2013.

Aids.gov. Syphilis and HIV: A Dangerous Duo Affecting Gay and Bisexual Men. Available online at http://blog.aids.gov/2012/12/syphilis-and-hiv-a-dangerous-duo-affecting-gay-and-bisexual-men.html through http://blog.aids.gov. Posted December 13, 2012. Accessed January 2013.

American Sexual Health Association. Syphilis. Available online at http://www.ashastd.org/std-sti/syphilis.html through http://www.ashastd.org. Copyright 2012. Accessed January 2013.

WebMD. Sexual Conditions Health Center: Syphilis Tests. Available online at http://www.webmd.com/sexual-conditions/syphilis-tests through http://www.webmd.com. Last Updated: September 29, 2011. Accessed January 2013.

MedlinePlus Medical Encyclopedia. FTA-ABS test. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003512.htm. Last updated August 24, 2011. Accessed January 2013.

MedlinePlus Medical Encyclopedia. RPR test. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003533.htm. Last updated August 14, 2012. Accessed January 2013.

MedlinePlus Medical Encyclopedia. VDRL. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003515.htm. Last updated August 24, 2011. Accessed January 2013.

Liu, H et al. New Tests for Syphilis: Rational Design of a PCR Method for Detection of Treponema pallidum in Clinical Specimens Using Unique Regions of the DNA Polymerase I Gene. J Clin Microbiol. 2001 May; 39(5): 1941–1946. Available online at http://www.ncbi.nlm.nih.gov/pmc/articles/PMC88053/ through http://www.ncbi.nlm.nih.gov. Accessed January 2013.

Grange, PA et al. Evaluation of a PCR Test for Detection of Treponema pallidum in Swabs and Blood. J Clin Microbiol. 2012 March; 50(3): 546–552. Available online at http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3295187/ through http://www.ncbi.nlm.nih.gov. Accessed January 2013.

Zanto, Susanne Norris. Syphilis Testing Guidelines. PDF available for download at http://www.aphl.org/conferences/proceedings/Documents/2009/2009_APHL_Annual_Meeting/028Zanto.pdf through http://www.aphl.org. Accessed January 2013. 

Centers for Disease Control and Prevention. Sexually Transmitted Diseases Treatment Guidelines, 2010. Diseases Characterized by Genital, Anal, or Perianal Ulcers. Available online at http://www.cdc.gov/std/treatment/2010/genital-ulcers.htm through http://www.cdc.gov. Accessed January 2013.

Syphilis Testing Algorithms Using Treponemal Tests for Initial Screening --- Four Laboratories, New York City, 2005--2006. MMWR August 15, 2008, 57(32);872-875. Available online at http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5732a2.htm through http://www.cdc.gov. Accessed January 2013.

Sources Used in Previous Reviews

National Institute of Allergy and Infectious Diseases: Syphilis. Available online at http://www.niaid.nih.gov/factsheets/stdsyph.htm through http://www.niaid.nih.gov.

Centers for Disease Control: Syphilis Fact Sheet. Available online at http://www.cdc.gov/std/Syphilis/STDFact-Syphilis.htm through http://www.cdc.gov.

American Social Health Association. Syphilis Fast Facts. Available online at http://www.ashastd.org/learn/learn_syphilis_facts.cfm through http://www.ashastd.org.

Wu, A. (2006). Tietz Clinical Guide to Laboratory Tests, Fourth Edition. Saunders Elsevier, St. Louis, Missouri. Pp 1612-1614.

ARUP Consult. Syphilis Testing Algorithm. PDF available for download at http://search.arupconsult.com/search/ through http://search.arupconsult.com. Accessed June 2009.

ARUP Consult. Treponema pallidum – Syphilis. Available online at http://www.arupconsult.com/Topics/InfectiousDz/Bacteria/Syphilis.html through http://www.arupconsult.com. Accessed June 2009.

MedlinePlus Medical Encylopedia: Syphilis. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/001327.htm. Accessed June 2009.

Centers for Disease Control and Prevention. Syphilis Fact Sheet. Available online at http://www.cdc.gov/std/Syphilis/STDFact-Syphilis.htm through http://www.cdc.gov. Accessed June 2009.

Centers for Disease Control and Prevention. STD surveillance, 2007. Available online at http://www.cdc.gov/std/stats07/syphilis.htm through http://www.cdc.gov. Accessed August 2009.

U.S. Preventive Services Task Force. Screening for Syphilis Infection in Pregnancy: U.S. Preventive Services Task Force Reaffirmation Recommendation Statement. Annals of Internal Medicine 19 May 2009, Volume 150, Issue 10, Pp 705-709.

MedlinePlus Medical Encyclopedia: VRDL. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003515.htm. Accessed June 2009.

MedlinePlus Medical Encyclopedia: FTA-ABS. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003512.htm. Accessed June 2009.

MedlinePlus Medical Encyclopedia: RPR. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003533.htm. Accessed June 2009.

WebMD. Syphilis Tests. Available online at http://www.webmd.com/sexual-conditions/syphilis-tests through http://www.webmd.com. Accessed June 2009.