Treponema Pallidum Antibody(TPAB) test

TPAB test

Last Updated December 20th, 2021

What is TPAB or Treponema Pallidum Antibody?

One of the oldest diseases that have been affecting mankind is syphilis and before the antibiotics were discovered, it affected up to 10% of the adult populations in the Western World. The disease is transmitted through sexual activity and is caused by the Treponema pallidum bacteria. It is a gram-negative bacteria that has helically coiled, corkscrew-shaped cells.

Apart from the formation of lesions, the disease can also lead to cardiovascular and neurologic problems. For pregnant women, it can cause serious birth defects and even fetal death and can get passed on to the unborn child. While the primary stage of the disease is confined at the site of infection, it generates a range of symptoms in the secondary stage. The test is used to diagnose an infection that is suspected of being caused by bacteria.

What is the TPAB test?

This test is an antibody test and it is done by collecting a sample of the blood from a vein. In the case of syphilis, the most common tests that are used are the nontreponemal antibody test and the treponemal antibody test. In most cases, a positive result from one test is followed by the other so that confirmation of the disease can be made. The nontreponemal antibodies are not specifically directed at the Treponema pallidum bacterium.

Conditions like pregnancy, Lyme disease, certain types of pneumonia, malaria, tuberculosis, and lupus can generate false-positive results. The Treponemal antibody tests are more specifically directed at the syphilis bacteria and more accurate. But once these antibodies are formed, they remain in the blood for a lifetime and a positive result in the test may not indicate an active state of the disease.

What is the main application of the TPAB test?

For confirmation of syphilis, a combination of both these tests is used. Currently, the reverse algorithm method is followed in which the treponemal testing is used first.

The reactive results are followed by confirmation through the nontreponemal test. The disease is generally categorized into four different stages which are the primary, secondary, latent and the late or tertiary stage. The bacteria is highly invasive and in some cases, the late-stage can occur much later, which in some cases maybe 20 to 30 years.

Treponema pallidum bacterium cannot be cultured by using standard laboratory methods and hence various other methods are used in testing. Among them, the dark Field Microscopy and the Polymerase chain reaction are two widely used methods.

Why do I need to undergo a TPAB test?

The test is ordered when there are specific physical symptoms of the disease. These can include the following.

– Lesions or ulcers on the genitals or throat

– A skin rash that often is rough, red, and spotted, appearing frequently on the palms of the hands and the bottoms of the feet. These rashes usually do not itch.

– This may be accompanied by other symptoms like fever, fatigue, swollen lymph nodes sore throat and body aches. Other symptoms include weight loss, hair loss, and headaches.

The test is also ordered in other scenarios which include the following situations.

– In case the patient is being treated for another sexually transmitted disease, such as gonorrhea.

– In case the patient has multiple sex partners or has a partner who has multiple sex partners.

– When the patient is pregnant, during the first prenatal visit and again in the third trimester and at the time of delivery if the woman is at high risk.

– When the patient engages in unprotected sex with multiple partners.

– For patients who have an HIV infection and a sexually active life, the test is done yearly.

– For anyone who has one or more partners who have tested positive for syphilis.

– For monitoring treatment and determining if treatment is yielding positive results.

How is a TPAB test performed?

The test is performed by a method called venepuncture which involves a collection of blood from a vein that is usually chosen from the elbow region. A needle is inserted into the vein and a small amount of blood is drawn into a vial. Before the needle is inserted the spot is disinfected and after the process is complete, the pressure is applied to the area using cotton or gauze to prevent any blood loss.

– A slight sting is felt when the needle is inserted in the vein and the spot can remain sore for a few days. The process is safe and takes a few minutes, though in some cases a patient can feel faint after the withdrawal process.

– In some patients, the size of the veins may be thinner and hence multiple punctures may be needed. Infections in the collection site are rare and should be treated after consulting a doctor.

– The advanced stages of the disease can affect the brain and spinal cord. In such cases, the testing can be done by collecting a sample of the cerebrospinal fluid (CSF) from the spinal cord. This is more time taking a procedure that is called a lumbar puncture. It involves the following steps.

-You will lie on your side or sit on an exam table and the technician will inject an anesthetic in the collection site.

Once the area on your back is completely numb, a special thin, hollow needle in the space between two vertebrae in the lower spine. A small amount of fluid from this chamber will be drawn out through the needle.

– You’ll need to stay very still during the entire procedure.

– The technician may ask you to lie on your back for an hour or two after the procedure and keep you under observation.

– It is best to take the help of someone while going back to your home after the lumbar puncture as the effect of the anesthetic takes some time to wear off. You may be affected by a headache after the procedure. There will be some feel some pain on tenderness in the collection spot for a few days.

What is the price of a TPAB test in India? 

The cost of the test ranges between Rs 500 to Rs 1500 depending on the place and facilities provided in the testing center.

When will I get the test results?

The test results are generally delivered within 2 to 5 days.

What is the normal range for a TPAB test?

The test detects the presence of antibodies in the blood and hence there is no specific range for it. The results are classified as positive, negative or normal depending on the detection.

What do the results mean?

A negative or normal result indicates that no syphilis infection was found. Antibodies take some time to form in the system so if the symptoms persist, the doctor may order another test after a week. In case of a positive result, further tests are conducted to confirm a syphilis infection. After confirmation, the treatment is generally done through the administration of specific antibiotics. Most syphilis infections are cured after the treatments.

Do I need to fast for the TPAB test?

No fasting is needed for the test whether it is conducted on a blood sample or a CSF sample.

What else do I need to know before I appear for a TPAB test?

The following points can be kept in mind for a better understanding of the test and the disease.

– After successful treatment through antibiotics, nontreponemal antibodies disappear over time but the treponemal antibodies remain present in the blood for life.

– There are many other sexually transmitted diseases apart from syphilis and hence in case of any suspicion, you should consult a doctor immediately. In case of any infection, your partner should also undergo the tests.

– In case you are using antibiotics or have undergone a blood transfusion within a few weeks, you should inform your doctor before the test.

– Conditions like lupus, liver disease, HIV infection and a tropical bacterial infection called yaws can also affect the test results.

– Syphilis also enhances your chances of getting infected with HIV. In case you have syphilis sores you should also get yourself tested for HIV.

– Neurosyphilis due to Treponema pallidum can occur at any time after the initial infection and the external manifestations of the same can vary depending on the stage of the disease.

Can pregnant women undergo a TPAB test?

Pregnant women can undergo the test without any restrictions

Is the TPAB test possible for new-born babies?

The test can be conducted for new-born babies as advised by the doctor.


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