Late-Stage Syphilis: Why RPR and VDRL Tests May Show Negative Results

Q: Late-Stage Syphilis: Why RPR and VDRL Tests May Show Negative Results

If there is an infection but no treatment is administered, the RPR (Rapid Plasma Reagin) test will not decrease. <br>If repeated tests consistently show negative results, it should indicate that there is no infection.

Can late-stage syphilis be undetectable in tests? (2)

1.
The VDRL (Venereal Disease Research Laboratory) agglutination test typically becomes positive about 4 to 6 weeks after infection or 1 to 3 weeks after the onset of initial symptoms.
In secondary syphilis, it often maintains a high titer (> 1:32), but in late syphilis, it may show a low titer (< 1:4) or even become negative.
2.
In the early stages of chancre, the serological response for syphilis is often negative, and it can also be negative in late syphilis, particularly in patients with neurosyphilis, where the negative rate can reach 30-50%.
Regarding your question, RPR/VDRL tests typically show an increase during infection and gradually decrease after successful treatment, but they do not necessarily return to zero.
Syphilis is less likely to have a prolonged window period as you described.
I understand that RPR/VDRL levels decrease after treatment, but my concern is whether, if someone is infected with syphilis and does not get tested (and therefore does not receive treatment), after 10 or even 20 years, the RPR or VDRL tests could yield negative results.
My concern is not about the window period, but rather whether late-stage syphilis could result in RPR/VDRL tests being negative.
I had risky behavior at 18, and I only got tested at 26 and 30 years old (both RPR tests were negative).
I am worried that the long duration might affect the test results.

Niming, 30~39 year old female. Ask Date: 2015/08/06

Dr. Wu Yuxin reply Dermatology

If there is an infection but no treatment is administered, the RPR (Rapid Plasma Reagin) test will not decrease.
If repeated tests consistently show negative results, it should indicate that there is no infection.

Reply Date: 2015/08/06

More Info

Late-stage syphilis can indeed present unique challenges when it comes to serological testing, particularly with the RPR (Rapid Plasma Reagin) and VDRL (Venereal Disease Research Laboratory) tests. These tests are non-treponemal tests used to screen for syphilis, and their results can vary significantly depending on the stage of the infection and the individual's immune response.

In the early stages of syphilis, typically within 4 to 6 weeks after infection, RPR and VDRL tests usually yield positive results. This is because the body produces antibodies in response to the Treponema pallidum bacteria, which causes syphilis. During the secondary stage, these tests often remain positive and can show high titers (values greater than 1:32). However, as the disease progresses to late-stage syphilis, particularly in cases of tertiary syphilis or neurosyphilis, the test results can become more complicated. It is not uncommon for RPR and VDRL tests to show lower titers (less than 1:4) or even become negative in late-stage syphilis. This phenomenon can be attributed to several factors, including the body's immune response and the potential for the disease to enter a latent phase.

Regarding your concern about being infected with syphilis for many years without testing, it is essential to understand that if a person has been infected with syphilis and has not received treatment, the RPR and VDRL tests should still yield positive results, even after many years. The tests may not necessarily return to negative unless the infection has been treated effectively. However, there are instances where individuals with late-stage syphilis may have negative RPR or VDRL results, particularly if they have developed complications such as neurosyphilis, where the serological response can be muted.

The negative results you have experienced at ages 26 and 30 could suggest that you may not have been infected with syphilis, especially if you have engaged in high-risk behaviors. It is also important to consider the possibility of false-positive or false-negative results, which can occur due to various factors, including other medical conditions or the presence of certain antibodies that may interfere with the test results.
In summary, while late-stage syphilis can lead to negative RPR and VDRL results, if you have been infected and untreated, you would typically expect to see positive results. If your tests have consistently been negative, it is likely that you have not been infected with syphilis. However, if you have concerns about your sexual health or potential exposure to syphilis, it is crucial to consult with a healthcare professional who can provide appropriate testing and guidance. Regular screening, especially for individuals with risk factors, is essential for early detection and treatment of sexually transmitted infections.

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