Does a positive syphilis antibody mean that you have syphilis?

In the physical examination report, does a diagnosis of positive syphilis antibodies mean that the person being examined is infected with syphilis? Many people who undergo physical examinations become very worried and confused when they find that their syphilis antibodies are positive, and they are not sure whether they have syphilis. In fact, a positive syphilis antibody test can be a false positive in medicine, which means it does not necessarily mean that you have syphilis.

A while ago, I encountered a case of a 19-year-old female college student who had a tooth extracted and underwent routine tests for syphilis and AIDS in our hospital's Department of Stomatology. The results showed that she was RPR positive (1:2) and TPPA negative. She had the same result after a repeat examination the next day, so she was transferred to the Dermatology Department. The girl said that she had only had one boyfriend, and that his tests had all been negative. She herself did not have any symptoms of discomfort, and her medical history did not show any vulvar ulcers or skin erythema. She underwent tests for TORCH, autoantibodies, tumor markers, etc., and the results showed that the Rubella virus IgM antibody was positive. She was asked to rest for a while, and a month later, the syphilis serological test was repeated. Sure enough, RPR and TPPA were both negative, which was a false alarm.

The final conclusion of this case is that it is an acute biological false positive of RPR caused by rubella virus infection. In layman's terms, the RPR positivity was caused by rubella virus infection, not the real Treponema pallidum, and the girl did not actually have syphilis.

In "How to interpret the results of syphilis blood test (syphilis serological test)? 》In the article. Among them, RPR is a non-syphilis Treponema pallidum antigen serum test. Other commonly used tests of this type in clinical practice include VDRL, USR, TRUST, etc. A false positive reaction to non-treponemal serology means that there is no true syphilis infection in the body, but the serological reaction is positive.

Below I will briefly introduce the situations in which false positives of non-syphilis treponema serum may occur (such as RPR positive, TPPA negative):

Technical false positive: caused by errors in specimen collection, storage, transportation and laboratory operation, which can be confirmed as negative by repeated tests;

Biological false positive: In fact, there is no syphilis infection but a positive reaction caused by other non-technical factors. This situation occurs in about 1/4000 in the "normal" population.

Biological false positive reactions are divided into acute and chronic. Acute means that the false positive lasts for a very short time. It usually turns negative a few weeks after the condition has improved. The course of the disease rarely lasts more than half a year. It is common in the following diseases: rubella, chickenpox, infectious mononucleosis, infectious hepatitis, upper respiratory tract infection, pneumococcal pneumonia, viral pneumonia, vaccinia rash, etc.

Chronic biological false positives often last for more than several months or even years, and are common in the following diseases: systemic lupus erythematosus, autoimmune hemolytic anemia, discoid lupus erythematosus, polyarteritis nodosa, rheumatoid arthritis, Hashimoto's thyroiditis, rheumatic heart disease, Sjögren's syndrome, drug addicts, chronic nephritis, cirrhosis, systemic sclerosis, leprosy, etc.

We would like to remind all patients that the test results of syphilis serological tests are often very complex and changeable. We recommend that you seek clinical judgment from a professional dermatologist and never jump to conclusions on your own.