Difference Between VDRL and RPR

Syphilis is a well-known infection caused by the Treponema Pallidum, which is sexually transmitted. It can be completely cured if the appropriate tests are carried out for its diagnosis. It is highly contagious and can be transmitted easily by sexual contact or inherited since birth. For detecting syphilis, many tests are available which include Venereal Disease Research Laboratory and Rapid Plasma Reagin also known as VDRL and RPR respectively. Though both these tests have similar procedures, they have many differences.

VDRL v/s RPR

The main difference between VDRL and RPR Is that VDRL requires a microscope to see the reaction or results of a test and is an old form of test which is being used till today. Whereas, RPR does not need any microscope to know the result as the reactions or results are visible to our naked eyes and are an antigen of VDRL.

VDRL vs RPR

VDRL is a rest of blood that is done to detect the presence of syphilis infection into the body. This test counts the number of protein substances known as antibodies, which your body produces when it comes in contact with the Treponema Pallidum bacteria that causes syphilis. A sample of a spinal guild can also be used to carry out the VDLR test.

On the other hand, Rapid Plasma Reagin or known as RPR is also a blood test done to check your blood for any traces of syphilis infection. Just like the VDRL test, this test also detects any unidentified antibodies produced by your body when in contact with the Treponema Pallidum bacteria, which can be lethal if not treated.

Comparison Table Between VDRL and RPR

Parameters of ComparisonVDRLRPR
SpecimenThe only serum is heated and used.Both serum and plasma are used without heating.
AntigenBefore using, antigens are diluted.Antigens are not diluted.
Results readingResults are obtained microscopically from the slide.Results are obtained without using a microscope, directly from the card macroscopically.
SensitivityVDRL tests are less sensitive.RPR tests are more sensitive.
TechniqueVDRL tests are old and difficult to perform.RPR tests are handy and easy to perform.

What is VDRL?

The VDRL test is created to diagnose the presence of syphilis infection in your body. Treponema Pallidum bacteria infect the body by entering the inner lining of the mouth and private areas. This test doesn’t specifically search for the bacteria which is responsible for causing syphilis but also looks for the antibodies that are produced by your body in response to the antigens that the damaged cells produce.

Antibodies are the protein substances that are produced by the immune system for fighting against harmful bacteria and toxins. For doing this test accurately, any symptom of syphilis is not required as this test looks for the antibodies produced by your body against the syphilis infection. The VDRL test can be done without having any symptoms of syphilis. If there is a chance that you are infected with syphilis, your doctor will certainly recommend you to have a VDRL test.

The symptoms that can make your doctor order you for having this test include a small and painless sore, the lymph nodes around the sore getting swollen, and rashes on the skin that does not itch or irritate. During pregnancy, your doctor will check for syphilis using the VDRL test, as a part of your routine check-up, but that doesn’t mean that you have the symptoms of this infection. It is just a standard procedure.

What is RPR?

The Rapid Plasma Reagin test or the RPR is a test of the blood used to detect whether you have a syphilis infection or not. It works as a detection mechanism for any nonspecific antibodies produced by your body while fighting against syphilis infection. The RPR test signals the doctor about the condition of the infection in the body, due to which the doctors accordingly carry out the treatment process.

By doing this, the chances of the infection getting more severe will be eliminated and the disease will not be spread by a person who is infected but is unaware of his condition. Doctors recommend the RPR test for many reasons as it is a quick way for people who have a high risk of having a syphilis infection. It is also recommended if syphilis is present in a form of a sore and rash. RPR tests are also added in the routine check-up of a pregnant lady.

Instead of finding the bacteria responsible for the infection, the RPR test counts the antibodies in the blood of a person who is infected with syphilis and is also used for checking the treatment progress of active syphilis. After antibiotic therapy, an RPR test is done to know the number of antibodies which is dropped after the therapy.

Main Differences Between VDRL and RPR

  1. In the VDRL test, results are read using a microscope whereas, in the RPR test, no microscope is required for reading the results.
  2. Once the antigen in the VDRL test is reconstituted, it should be used with a day whereas, the antigen in the RPR test can be used within 6 months.
  3. In VDRL, the serum is preheated to eliminate any nonspecific inhibitors whereas, in RPR, choline chloride is used for removing inhibitors.
  4. VDRL test can be used to screen blood, serum, plasma, and CSF whereas RPR can only screen blood, plasma, and serum but not CSF.
  5. VDRL tests are difficult to be performed whereas RPR tests are easy and maximum people prefer it over VDRL. 

Conclusion

In conclusion, Venereal Disease Research Laboratory test (VDRL) and Rapid Plasma Reagin (RPR) both are nontreponemal tests that are used to check the antibodies produced by the body when in contact with the Treponema Pallidum bacteria which causes the syphilis infection, which is proven to be fatal when it is left untreated.

Both these tests can show false-positive results due to some specific circumstances like pregnancy or autoimmune diseases, due to which the treponemal test is required to confirm the presence of syphilis in the body. VDRL is an old technique that is difficult to perform yet used even today whereas, RPR is an advanced antigen of VDRL, which is easy to perform but expensive.

References

  1. https://onlinelibrary.wiley.com/doi/abs/10.1002/jcla.20254
  2. https://www.revistas.ufg.br/index.php/iptsp/article/view/3173
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