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Syphilis

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
Formal name: Syphilis detection test
Related tests: Hepatitis C; HIV antibody test

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?

If you have symptoms of a syphilis infection, if you have another STD, or are pregnant

Sample Required?

A scraping from a chancre in the affected area, a blood sample from a vein in your arm, or cerebrospinal fluid taken via a spinal tap, depending on the test method being used

Test Preparation Needed?

None

The Test Sample

What is being tested?

The test is looking for presence of Treponema pallidum, the bacterium that causes syphilis. Syphilis is an infectious disease that is most often spread by sexual contact, such as through direct contact with a syphilis sore (chancre). It is easily treated but can cause severe health problems if left untreated. An infected mother can also pass the disease to her fetus, with serious and potentially fatal consequences for the baby.

According to the US Centers for Disease Control and Prevention (CDC), over 40,000 cases of syphilis were reported in 2007, including 11,466 cases of primary and secondary (P&S) syphilis. Most of the P&S syphilis cases in 2007 occurred in individuals 20 to 29 years of age.

There are several stages with syphilis. The primary stage begins about 2-3 weeks after being infected. One or more sores, called chancres appear, usually on the part of the body exposed to your partner's chancre, such as 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.

Secondary syphilis begins 2-8 weeks 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. There may be other symptoms as well, such as fever, fatigue, swollen lymph glands, sore throat, and body aches. If untreated, 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. This stage can last for years, with the final stage leading to mental illness, blindness, other neurological problems, heart disease, and death.

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

How is the sample collected for testing?

There are several different screening methods and tests; therefore, different samples are needed.

  • For new infections, your doctor may take a scraping from a chancre on the affected area, such as the cervix, penis, anus, or throat.
  • Your doctor may have blood drawn from a vein in your arm for an additional test.
  • If you have late or latent stages of the disease with suspected brain involvement (neurosyphilis), your doctor will order a spinal tap to check your 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

How is it used?

The tests are used to screen for and diagnose infection with Treponema pallidum, the bacterium that causes syphilis. Screening of all pregnant women is recommended by the US Preventive Services Task Force, preferably at the first prenatal visit. Many states require a blood test for syphilis when a couple is applying for a marriage license in order to help prevent the spread of the infection to others, especially a newborn baby.

There are several methods that can be used to test for syphilis. One method used in diagnosis of early cases involves looking for the bacterium in scrapings from the chancre using a special instrument called a dark-field microscope. Other methods require a blood sample in which antibodies can be detected. These include:

  • For screening – VDRL which stands for “venereal disease research laboratory” test and rapid plasma reagin test (RPR)
  • For diagnosis - fluorescent treponemal antibody absorption test (FTA-ABS) and Treponema pallidum particle agglutination assay (TPPA)

A method called microhemagglutination assay, MHA-TP, is rarely used any more.

Response to treatment can be determined with a follow-up RPR test, and the FTA-ABS test is used to confirm a positive VDRL or RPR screening test. In late or latent syphilis, cerebrospinal fluid (CSF) may be obtained using a spinal tap and then tested in order to diagnose brain involvement (neurosyphilis).

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When is it ordered?

A doctor may order the test:

  • if you have symptoms, such as a chancre on the genitals or throat;
  • if you are being treated for another sexually transmitted disease, such as gonorrhea;
  • if you are pregnant, because untreated syphilis can infect and even kill a developing fetus; or
  • if you complain of non-specific symptoms that resemble those of syphilis, to determine the exact cause of your illness.

If you are infected, you should have follow-up blood tests at 3, 6, 12, and 24 months to make sure the infection is gone following treatment.

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What does the test result mean?

If a scraping reveals presence of the syphilis bacterium (a positive test), you have an infection that requires treatment with a course of antibiotics, preferably penicillin.

For the blood tests that detect the antibodies that the body produces to combat infection, a positive test indicates that you have either a current or past infection. However, a negative test does not always mean that you do not have syphilis.

Antibodies may not be able to be detected for up to three months after exposure to the bacteria, and the antibodies remain in the body for years. If you have had a past infection with syphilis and were treated, your test results could still be positive. For example, a FTA-ABS test may remain positive for life even if you have been treated. To avoid being retreated, keep a record of the previous treatment and show it to your doctor. Following treatment, syphilis antibodies should be lower and can be monitored with the titered RPR test; if they remain the same or rise, you may have a persistent infection.

The different tests available to screen and diagnose syphilis vary in their accuracy depending on the stage of disease. For example, the VDRL and RPR tests have highest sensitivity during the middle stages.

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Is there anything else I should know?

Screening tests for syphilis are not highly specific and may give a false positive result. For example, having HIV, Lyme disease, malaria, lupus, or certain types of pneumonia may cause a false positive result on the VDRL and RPR tests. Positive tests should be confirmed with a more specific test method, such as FTA-ABS.

If you are sexually active, you should consult your doctor about any suspicious rash or sore in the genital area.

If you are infected, tell your sexual partner(s) to get tested and treated.

If you are infected, your risk of contracting other sexually transmitted diseases increases, including the risk of being infected with HIV, the virus that causes AIDS. The chancres caused by syphilis make it easier to transmit and acquire HIV.

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Common Questions

1.  How long does it take to get results from a syphilis test?

If the specimen is examined microscopically by the doctor, then results could be immediately available. Otherwise, blood and CSF tests are sent to a laboratory and results could take three to five days.

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2.  How can syphilis be prevented?

For information on prevention, visit the American Social Health Association's STD/STI Prevention Tips.

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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

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.

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.