False Positives and Rapid Recovery in Syphilis Testing

Q: False Positives and Rapid Recovery in Syphilis Testing

Hello： 1) I was recently diagnosed with syphilis in the United States, with an RPR of only 1：1 and a reactive FTA-ABS. <br>On the day of the blood draw, I received a preventive treatment with a dose of penicillin based on my physician's recommendation. <br>A few days later, I rec

Regarding false positives in syphilis and the determination of cure?

Hello, doctor.
(1) I was recently diagnosed with syphilis in the United States, with an RPR of only 1:1 and a reactive FTA-ABS.
On the day of the blood draw, I received a preventive treatment with a dose of penicillin based on my doctor's recommendation.
A few days later, I received the confirmation report.
What’s strange is that when I went for the second dose a week later, my RPR test showed negative.
Is it possible for syphilis to turn negative so quickly? What is the likelihood of a false positive on the first test? How should I verify this? After all, if I did have it, according to Taiwan's standards, I would need to be monitored for several years, which would significantly impact my life plans.
(2) The doctors here said that after treatment, the titers can only decrease and not increase.
They mentioned that it is safe to engage in sexual activity seven days after the injection (as stated by the CDC), and that if my next blood test (around three months later) shows negative or very low results, I would be considered cured and could live a normal life, including having children.
They also said that any case of rising titers would indicate a new infection.
Several doctors have said this; can I trust their statements? Why is there such a difference in perspective compared to Taiwan? Since I turned negative in just one week, I am unsure if I can safely interact with my family, engage in sexual activity, or plan for children if I remain negative after three months.
I appreciate your clarification on these matters.
Thank you.

Fei Si, 30~39 year old female. Ask Date: 2023/01/06

Dr. Du Shixi reply Urology

Hello: 1) I was recently diagnosed with syphilis in the United States, with an RPR of only 1:1 and a reactive FTA-ABS.
On the day of the blood draw, I received a preventive treatment with a dose of penicillin based on my physician's recommendation.
A few days later, I received the confirmation report.
What’s strange is that when I went for my second dose a week later, the RPR test showed negative.
Is it possible for syphilis to turn negative this quickly? What is the likelihood of a false positive on the initial test? How should I verify this? After all, if I indeed had it, according to Taiwan's standards, I would need to be monitored for several years, which would significantly impact my life plans.
If I have several tests that come back normal, is that sufficient? (2) The doctors here say that after treatment, the titers can only decrease and not increase.
They mentioned that I can engage in safe sexual practices seven days after the injection (the CDC indeed states this), and as long as my next blood test (around three months later) shows negative or very low results, I would be considered cured and can live normally, including having children.
If there is a rise in titers, it would indicate a new infection.
Several doctors have said this; can their statements be trusted? Why is there such a significant difference in perspective compared to Taiwan? Since I turned negative in just one week, I am uncertain if I can safely interact with my family, engage in sexual activities, or plan for children if I remain negative after three months.
--> If confirmed, monitoring for several years is necessary.
If there is an increase, further treatment is required.
Therefore, after treatment, if the titers decrease, one can live safely, but monitoring is essential.

Reply Date: 2023/01/06

More Info

Understanding the complexities of syphilis testing and treatment can be quite challenging, especially when faced with conflicting information from different healthcare providers. Let's break down your questions and concerns regarding your recent syphilis diagnosis and the subsequent testing results.

(1) Rapid Recovery and False Positives
You mentioned that your RPR (Rapid Plasma Reagin) test showed a result of 1:1, and the FTA-ABS (Fluorescent Treponemal Antibody Absorption) was reactive. After receiving a dose of penicillin, you later tested negative for RPR within a week. This rapid change in your RPR result can be surprising, but it is not entirely unheard of.
The RPR test is a non-treponemal test, which means it detects antibodies that may not be specific to syphilis. These antibodies can sometimes be present due to other conditions, leading to false positives. Factors such as recent infections, autoimmune diseases, or even pregnancy can cause these non-specific antibodies to appear. Therefore, the likelihood of a false positive in your initial test cannot be dismissed, especially if you had no prior symptoms or known exposure.

To verify your diagnosis, it is essential to follow up with treponemal tests like the FTA-ABS, which are more specific to syphilis. If your FTA-ABS remains reactive while your RPR becomes non-reactive, it may indicate that you had a past infection that has been successfully treated, as treponemal tests can remain positive for life even after successful treatment.

(2) Treatment and Future Interactions
Regarding the treatment and the timeline for safe sexual activity, the information provided by your healthcare providers aligns with guidelines from the Centers for Disease Control and Prevention (CDC). After treatment with penicillin, it is generally accepted that individuals can resume sexual activity after seven days, provided they have no symptoms and their follow-up tests show a significant decrease in RPR titers.

The notion that RPR levels should only decrease post-treatment is accurate; however, it is crucial to understand that a negative RPR test does not automatically mean you are free from syphilis, especially if the FTA-ABS remains positive. The CDC recommends follow-up testing at three, six, and twelve months after treatment to monitor for any potential reinfection or treatment failure.

Cultural Differences in Medical Perspectives
The differences in medical perspectives between the United States and Taiwan regarding syphilis management may stem from varying public health policies, healthcare practices, and cultural attitudes towards sexually transmitted infections (STIs). In the U.S., there is a strong emphasis on immediate treatment and follow-up, while in other regions, there may be more caution regarding sexual health and the implications of a syphilis diagnosis.

Conclusion
In summary, your rapid transition from a reactive to a non-reactive RPR test could suggest a few possibilities, including a false positive or a very effective response to treatment. It is crucial to continue monitoring your health with follow-up tests as recommended by your healthcare provider. If your FTA-ABS remains reactive, it is essential to discuss with your doctor the implications of this result and what it means for your future health and interactions with others.

Always prioritize open communication with your healthcare providers, and do not hesitate to seek a second opinion if you feel uncertain about the information you receive. Your health and peace of mind are paramount, and understanding your condition fully will help you make informed decisions moving forward.

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