Blood-tests Explained


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This website is intended to assist with patient education and should not be used as a diagnostic, treatment or prescription service, forum or platform. Always consult your own healthcare practitioner for a more personalised and detailed opinion

Syphilis


At a Glance

Why Get Tested?

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

When to Get Tested?

When you have symptoms of a syphilis infection; when you are at risk of being exposed to syphilis, such as when you have another STD or HIV infection, are a man who has sex with men, have a sexual partner diagnosed with syphilis, or have engaged in high-risk sexual activity; when you are pregnant

Sample Required?

Most often, a blood sample drawn from a vein in your arm; sometimes, a scraping from a chancre in the affected area; less commonly, cerebrospinal fluid taken via a spinal tap, depending on your clinical presentation

Test Preparation Needed?

None

The Test Sample

What is being tested?

Treponema pallidum bacteriaSyphilis is an infection caused by the bacterium 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 bacterium or its genetic material (DNA). Photo source: CDC

Syphilis is easily treated with antibiotics 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 2014, about one-third of over 63,000 new cases of syphilis reported to the Centers for Disease Control and Prevention (CDC) were primary or secondary stage syphilis. Eighty-three 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 healthcare practitioner 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 healthcare provider will perform a spinal tap to check the cerebrospinal fluid (CSF) for infection.

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

No test preparation is needed.

The Test