Test Detail
Overview
Interpreting Results
FAQ's

Content created by

Written by
Dr. Shreya Gupta
BDS, MDS - Oral and Maxillofacial Pathology
Reviewed by
Dr. Ashish Ranjan
MBBS, MD (Pharmacology)
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Treponema Pallidum Hemagglutination

(TPHA)
Treponema Pallidum Hemagglutination
You need to provide
Blood
This test is for
Male, Female
Test Preparation
  1. No special preparation required

Overview


What is TPHA?

Treponema Pallidum Hemagglutination (TPHA) test is used to detect antibodies in the blood against syphilis, which is a sexually transmitted disease. Syphilis is caused by bacteria, namely,  “Treponema pallidum”. It spreads if a person comes in direct contact with a syphilitic lesion (chancre). It has three possible stages which include primary syphilis, secondary syphilis, and late or tertiary syphilis.


Why is TPHA done?


  • To diagnose Treponema pallidum infection

  • To screen for sexually transmitted diseases

  • To monitor the treatment of syphilis


What does TPHA Measure?

Syphilis is a sexually transmitted disease (STD) caused by the bacteria Treponema pallidum. It is most commonly spread by sexual route for example through contact with a syphilitic sore (Chancre). Syphilis is treatable with antibiotics, but it can cause severe health problems if left untreated and can be potentially fatal. It can be transferred from an infected pregnant mother to an unborn child which can lead to serious and potentially fatal consequences for the baby.

There are several stages of syphilis:

·       Primary syphilis: Primary stage starts after 2-3 weeks of being infected and usually presents with one or more painless chancres on that part of the body which was exposed to the sexual partner's chancre such as on the penis or vagina. Since it is painless, it may go unnoticed, especially if it is in the rectum or on the cervix. It usually disappears within 4-6 weeks even without any treatment.

·       Secondary syphilis: From 6 weeks to 6 months after the chancre first appears, primary syphilis can progress to secondary syphilis if the infected person is left untreated. Its symptom is non-itchy skin rash (rough, red, and spotted) appearing typically on the palms of the hands and the bottoms of the feet. Other symptoms could be fever, fatigue, swollen lymph nodes, sore throat, and body aches.

·       Late or tertiary syphilis: If left untreated in previous stages, secondary syphilis can progress to late or tertiary stage in which an infected person may be asymptomatic but continues to have the infection, and this stage can last for years. Complications of tertiary syphilis can occur if still left untreated. The bacteria can damage the heart, eyes, brain, central nervous system (Neurosyphilis), bones, joints, or almost any other part of the body. Tertiary syphilis can last for years and the final stage can lead to mental illness, blindness, other neurological problems, heart disease, and even death.

Interpreting TPHA results


Interpretations

A negative test result means that antibodies against Treponema Pallidum are absent indicating that the patient is not having syphilis infection

A positive test result means that antibodies against Treponema Pallidum are present indicating that the patient is having syphilis infection

However, false positive and false negative test results can also be seen in some cases. All test results should be clinically correlated.

All positive tests should be confirmed with Fluorescent Treponemal Antibodies (FTA-ABS) test.


Answers to Patient Concerns & Frequently Asked Questions (FAQs) about TPHA


Frequently Asked Questions about Treponema Pallidum Hemagglutination

Q. How is this test performed?
This test is performed on a blood sample. A syringe with a fine needle is used to withdraw blood from a blood vessel in your arm. The healthcare provider will tie an elastic band around your arm to make the blood vessels swell with blood. This makes it easier to withdraw blood. You may be asked to tightly clench your fist. Once the veins are clearly visible, the area is cleaned with an antiseptic solution and then the needle is inserted into the blood vessel to collect the sample. You will feel a tiny pinprick during the procedure. Blood sample once collected will then be sent to the laboratory.
Q. Is there any risk associated with this test?
There is no risk associated with the test. However, since this test involves a needle prick to withdraw the blood sample, in very rare cases, a patient may experience increased bleeding, hematoma formation (blood collection under the skin), bruising or infection at the site of needle prick.
Q. Is there any special preparation required for the test?
No, there is no special preparation required for the test.
Q. What other tests are required for diagnosis of syphilis?
Following are different types of tests available that can diagnose syphilis: 1. Antibody tests (serology): Antibody tests are most commonly used. These tests detect antibodies in the blood and cerebrospinal fluid (CSF). Two types of tests available for syphilis testing are nontreponemal antibody test and treponemal antibody test. Any of these two types can be used for syphilis screening, but it must be followed by a second test that uses a different method to confirm a positive result and to diagnose active syphilis. Nontreponemal antibody tests—These are called "nontreponemal", as they detect antibodies that are not specifically directed against the syphilis bacteria Treponema pallidum. Besides syphilis, these antibodies can also be produced in several other conditions (false positive results). The tests are highly sensitive but are non-specific in nature. False-positive results can be seen in IV drug use, pregnancy, Lyme disease, certain types of pneumonia, malaria, tuberculosis, or certain autoimmune disorders including lupus. A positive screening result must be confirmed with a more specific (treponemal) test. Nontreponemal tests include RPR (Rapid Plasma Reagin) test and VDRL (Venereal Disease Research Laboratory) test. · Treponemal antibody tests: These blood tests detect antibodies that specifically target Treponema pallidum. They are highly specific for syphilis. However, once a person is infected and these antibodies develop, they remain in the blood for life. On the other hand, nontreponemal antibodies typically disappear in a well treated person after about 3 years. Therefore, a positive treponemal screening results must be followed by a nontreponemal test (such as RPR) to differentiate between an active infection (or reinfection) and one that occurred in the past and was successfully treated. Treponemal antibody tests include FTA-ABS, TP-PA, and MHA-TP. FTA-ABS (Fluorescent treponemal antibody absorption) test is used to diagnose neurosyphilis. Sometimes instead of FTA-ABS test, TP-PA (T. pallidum particle agglutination assay) test is performed because it is more specific and there are fewer false positives. MHA-TP (Microhemagglutination assay) is another confirmatory method, however, this test is used much less commonly now. Immunoassays (IA): in more recent years, several automated tests have been developed, making them convenient for screening purposes. 2. Direct detection of bacteria—These tests are less commonly used now. Dark field microscopy may be used in the early stages of syphilis when a suspected syphilis sore (chancre) is present. It involves obtaining a scraping of the sore, placing it on a slide, and examining it with a special instrument called a dark-field microscope. 3. Molecular testing (polymerase chain reaction, PCR): This test detects genetic material from the bacteria in the sample obtained from the sore, in the blood, or in CSF.
Q. What do you mean by false-negative TPHA test results?
False negative means negative results of TPHA test in the presence of syphilis infection. The body does not always produce antibodies specifically in response to the syphilis bacteria, so the test is not always accurate. False-negatives may occur in people with early- and late-stage syphilis. Hence, to accurately detect syphilis other tests are required as well.
Q. What do you mean by false positive TPHA results?
False positive means positive results in the absence of syphilis. TPHA test is not specific for syphilis, as it does not differentiate between other treponemal antibodies from syphilis, although it is highly sensitive. A false-positive TPHA can be encountered in infectious mononucleosis, leprosy, and connective tissue disorders.
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