Avatar universal

Positive VDRL and negative TPHA

I had unprotected oral sex in August (7th and 24th), and noticed a bad sore throat and swollen cervical nodes by September 6th. This didn’t subside for many weeks. I was put on amoxicillin for five days, which didn’t help. An ENT put me on cefalodoxime which I’m still taking but it hasn’t helped. I also noticed a small painful pimple on my anus (but I don’t practice anal sex). I did an HIV and VDRL rapid tests on October 2nd (nearly 6 weeks from last incident). HIV was negative but VDRL was positive. The ENT specialist wanted to confirm this and asked me to repeat VDRL and HIV in addition to TPHA at a different lab. The HIV (this time a combo test), came out negative exactly six weeks from the day of exposure. The TPHA was negative too. However, the VDRL/RPR is positive at 1:32 dilution. Does this mean I was recently infected by syphilis and TPHA is not showing it? Or does this mean the VDRL is a false positive due to some other illness that is causing my sore throat and swollen nodes? I received my second dose covid vaccine (AstraZeneca) on the 10th of September. Could this have resulted in a false positive VDRL result? Or do I just have syphilis and I must get treated?
5 Responses
Sort by: Helpful Oldest Newest
207091 tn?1337709493
What is happening with the VDRL titers? Are they going up? Down?

The standard is that if you have a positive VDRL or RPR and a negative TPHA, the VDRL is a false positive.

I don't know that we have enough info on the covid vaccines to know if that contributes, but historically, vaccines haven't caused false positives. Things that can are autoimmune disorders, Lyme Disease, some tropical diseases like malaria, HIV.

Have you ever had syphilis before?

If you don't practice anal sex, the sore on your anus can't be a syphilis sore. Sores appear at the point of infection. Syphilis sores are flat, round and painless.
Helpful - 2
I’ve done VDRL tests in the past but they were negative. The last time I did it was 2 years ago. If my current six combo test for HIV reveals a non-reactive result, can HIV be ruled out as a cause for VDRL false positive? I have never had syphilis before as far as I know.
4859015 tn?1360119889
VDRL test may give false positive results and it happens not so rarely. There are many causes for this, and a vaccine is unlikely one of those.
Anyway, VDRL is an indirect test, while TPHA is a specific treponemal test which is always more specific and more sensitive.
The pimple on your anus is unrelated, while there may be an unnoticed primary chancre in your mouth (assuming you gave oral sex). If you only received oral sex, you don't have to worry about syphilis.
No worries on HIV either.
As AuntieJesse said, positive VDRL plus negative TPHA should be considered a false positive. But there is a tiny possibility that TPHA test was wrong, so the doctor must be careful and must be 100% sure to rule out syphilis.
If you gave unprotected oral sex, I suggest doing another syphilis test, preferably a different combo (RPR + EIA or TPPA), just make sure it includes a specific treponemal test.
I wouldn't worry much since VDRL test is notorious for its false positives.
Helpful - 2
Sorry. I posted a comment below. This was meant for you: “ I gave a blowjob and rimmed as well. I have an appointment with an infectious disease specialist and I’ll be sure to tell her I’d like to do a treponemal test again.”
Okay, so there was a risk for syphilis.
It is a good idea to see a specialist. Do another test and keep us informed on your progress.
Avatar universal
I gave a blowjob and rimmed as well. I have an appointment with an infectious disease specialist and I’ll be sure to tell her I’d like to do a treponemal test again.
Helpful - 0
I agree with continuing to investigate this. Good luck and keep us posted. :)
I did see the infectious disease specialist who was quite eager to prescribe a volley of tests for chlamydia, gonorrhea, herpes, EBV, toxoplasmosis, hepatitis B and C, and finally three syphilis tests: VDRL, TPHA, and FTA AbS. She’s also asked for a neck ultrasound for the swollen nodes and said I will need a biopsy too (this of course shook me). And an HIV PCR RNA test because she doesn’t trust the combo test at six weeks. Isn’t it confirmatory at six weeks? Or is it possible that my false positive VDRL is related to a false negative HIV combo test?
Wow, that's a lot of tests. I am not sure every single one is necessary (herpes and EBV are certainly not), but okay.  The doctor is looking for the infection that makes your VDRL positive and toxo, EBV and hepatitis might be the culprits.
Three syphilis tests is a good call. You should expect positive VDRL and negative TPHA and FTA.
I am not an expert on HIV testing, but I see no reason for "not trusting" DUO test. False negative 4th gen HIV tests are quite rare. The gold standard is still an antibody test at 12 weeks, but you shouldn't worry about HIV.
Let us be patient and wait for those test results. Keep us posted, please.

Okay, I can understand the HIV test as procedural, because your syphilis tests don't make much sense. I wouldn't expect that to be positive, but she probably has to run that to rule that out.

A biopsy of your lymph nodes? I'm not sure I understand that one, but I'm not an infectious disease doc.

I'm sure these are just routine tests to rule things out, and I see no reason to expect your herpes, hep B and C tests, and probably EBV to be positive. Hep C is only transmitted by blood, and usually by sharing needles for drug use. You've likely been vaccinated for Hep B.

A note on the herpes tests - there are false positives on the hsv2 IgG tests. If your test result is positive, but below a 3.5, ask them to confirm it with a Western Blot. That's standard of care now, per the CDC.

Keep us posted.
Some bad news. VDRL is positive at 1:32 dilution. And TPHA is positive at 1:2560 dilution. I couldn’t find a lab that offers FTA antibodies. So i think that settles my doubt. The dermatologist I spoke to (not the infectious disease specialist) said my titers look like I’ve been infected for a very long time. Is that true? My last VDRL in 2019 September/October was negative.

I got the results of few of the many other tests I underwent. My HSV 1 and 2 (it doesn’t say which one is positive, one or two) IgM is reactive at 1.58 but IgG is non reactive at 0.78. My toxoplasmosis is reactive too (IgG - 41.9). The IgM is non reactive at 3. The Cytomegalovirus IgM is reactive at 56.20 but the IgG is non-reactive at 5.90.

Hepatitis B and C are non reactive. No I am not vaccinated against Hepatitis B yet.

I did a fine needle aspiration of my lymph node and the radiologist commented it looks like an infection. The results of the FNAC (needle biopsy) should be out tomorrow. The neck ultrasound revealed bilateral cervical lymphadenopathy and it says the cause seems to be an infection. The radiologist who did the ultrasound said it looked like tuberculosis and asked me to do a chest X-ray (turned out to be normal) and a complete blood count test. The CBC shows Red Cell Distribution Width as 11.50 (just lower than the lower range of 11.60). It also reveals a total leukocyte count of 11.70, which is above normal. Under differential leukocyte count, lymphocytes have been recorded as 17.50 which is lower than normal. Neutrophils are 8.51, slightly above normal.

I’m worried about the high titers of syphilis and also the positive Herpes result. I have multiple small lesions on my genitals. They have the same color as my skin but they shine as if they are dry. Some of these lesions are weepy as well. When they dry, they’ve left a wart-like lesion that peels too. Is this herpes or genital warts?  And the infectious disease specialist wanted me to do an HIV PCR to rule out completely. Is it really necessary in my case, considering a negative HIV combo report at six weeks?
Wow - they are just throwing it all at you, huh?

Ok, we'll start at herpes, because that's easiest to address. The IgM test looks for "new" antibodies. They fall off, so to speak, by about 6 weeks. So, this test shouldn't have been done on you. The other thing about the herpes IgM is that it is a terrible test. It is inaccurate and unreliable. Trust the IgG result, ignore the IgM. I'm surprised your ID doc even did that test. We've known for years it's a bad test.





Okay, "very long time" is subjective. The longest time it could be is 3 years because you had the negative test in 2019. I've seen longer. All it means is that you will get a series of 3 shots.

"Bilateral cervical lymphadenopathy" means you have swollen glands.

https://www.osmosis.org/answers/cervical-lymphadenopathy - this has a whole paragraph about how cervical lymphadenopathy can often be confused with cervical lymphadenitis, and how the latter can be caused by TB. Maybe  the radiologist got confused?

Usually, when something is just under or just over the range, it's not a concern, but again, I am not a specialist in any of this stuff.

The lesions - not sure what they are, but they could be molluscum. Warts don't weep, and herpes doesn't shine and isn't skin colored. Has the doctor seen them?

A lot of what this doctor is doing isn't necessary, like the hep tests. I don't see a need for the HIV PCR, if you had a 4th gen DUO test. I hope you have good insurance, if you're in the US.

4859015 tn?1360119889
Sad to hear you have syphilis; good news it is very curable. I have never heard of a negative TPHA turning positive, so I assume there was some human error involved. It was a good call to do another test. FTA test is not necessary, time to treat syphilis.
It is not possible to say for sure how long you have been infected. VDRL titer is not very high, so it may still be a new infection (end of primary stage, from that exposure 6 weeks ago). It might be an older infection, but I doubt you missed it a rash since 2019. I wouldn't worry about your titers, just do the treatment.
Every new syphilis case must be tested for HIV.
Your HIV RNA test must be procedural, but, since your TPHA test was botched, there may be something wrong with the lab which did the initial round of testing. I strongly recommend retesting for HIV at a different lab, but always keep in mind that only antibody test (not RNA) is conclusive. I would do another DUO test instead in a few weeks and wouldn't hurry.
You definitely have an infection (syphilis) and it may influence your lymph nodes and CBC, so no need to worry much on that. Syphilis is associated with enlarged lymph nodes, all over the body too, when secondary stage starts.
Multiple small lesions on your genitals might be genital herpes, AuntieJesse would probably tell more on that.
Helpful - 0
Hi @auntiejessi and @grobick2000. I am sorry I didn’t get back to you because I have had some very rough days and I didn’t want to post repeatedly. I started penicillin (2.4 million, 3 times) on the 11th of October, and took the remaining doses on the 18th and 25th. My dermatologist (not the infectious disease specialist. I long abandoned the "infectious disease specialist" because she started to insist I must get an excision biopsy done for my lymph node and refused treatment for syphilis until I did all the tests for TB including GeneXpert) curiously put me on doxycycline as well. She initially asked me to take 100 mg twice a day for 3 weeks, and when I went for a review yesterday, she asked me to take 100 mg for 3 more weeks, after the initial 3 weeks of 200 mg/day gets completed next week. I missed a dose this morning and I took two doxycycline capsules at dinner to make up for the missed dose. I doubt it was a smart idea. I read that penicillin interacts with doxycycline, which renders penicillin ineffective. My symptoms have improved and my lymph node has reduced in size. My rashes have begun to dry as well, and the ulcers have all vanished. How do I make sure I don’t have neurosyphilis or ocular syphilis? Also, I got tested again for HIV at a different lab close to 7 weeks from the date of exposure. It was negative. This was a CMIA combo test. The dermatologist insists I need to test after 3 months and this result is not reliable as it is too early. I am understandably anxious. Can I still have HIV or should I believe the 7 week combo test results? As penicillin may have been ineffective due to doxycycline, should I continue to taking 200 mg after the 3rd week instead of 100 mg as advised by the dermatologist? She also suspects LGV, although no tests were conducted for that. I think the doxycycline was prescribed for the presumptive LGV infection.
Yes, it seems like doxy may interfere with penicillin - https://www.medicinenet.com/amoxicillin_amoxil_vs_doxycycline_vibramycin/article.htm

The good news is that doxy is the second line treatment for syphilis, and is used in people who are allergic to penicillin, so there's that.

The only way you'll know if it's working for you is to test again and see your titers. Symptoms improving are a good sign, but it could be slowing the growth, not killing the bacteria.

I'd trust the 7 week combo test. You may need to do a 3 month to shut her up, but I'd expect it to be negative.

The only way to know for sure if you have neurosyphilis is to test your cerebrospinal fluid (CSF).

I can't tell you to stop or continue the doxy. That's something you need to address with your doctors.

Why are they suspecting LGV? And TB? I mean, you have syphilis - you aren't a walking infection of every disease known to man. Are you in an area that has high incidence of both?

Sorry, I again left a comment below. Also, could you please tell me if every person who is diagnosed with syphilis should also get a spinal tap?
First of all, treatment for syphilis is penicillin OR doxy, not both. I have read thousands of papers on syphilis treatment but have never seen such treatment regimen.
But the good thing is it should have worked. Your symptoms improving is a good sign.
I see no point in continuing doxy after the full course you've already taken. Now it is time to assess the treatment effect.
Now you should keep monitoring your VDRL titers every 3 months for a year. If the titers keep going down, the treatment is successful (it should be). You need to achieve 4-fold decrease of VDRL titers (from 1:32 to 1:8 or lower) to be completely cured. And don't do any treponemal tests like TPHA anymore, they are no use.
Now for the much feared neurosyphilis. No, not every person diagnosed with syphilis needs spinal tap. Neurosyphilis is quite rare and it normally develops late in the course of disease. While most textbooks say scary words about "may happen at any stage", it almost never happens that early as in your case.
I strongly advise against testing for neurosyphilis. It would do more harm than good in your case.
And stop doing all those HIV-tests. As for TB, don't do the biopsy yet. Wait for a few months.
Thank you. The dermatologist said she was prescribing the doxycycline for other possible STIs I might have. She said suspected a concurrent LGV. The prescription says “mixed STI. Syphilis + LGV ?”. Of course, no tests were conducted for LGV.

Will the doxycycline affect penicillin’s efficacy, and thus render this particular treatment a failure? Also, as many textbooks mention neurosyphilis can occur at any time, is it possible for syphilis to evade 3 shot penicillin/28 day doxy and remain in the central nervous system only to strike back decades later? And what harm may the spinal tap cause?
It is quite difficult to diagnose LGV, the test is quite expensive, so the treatment is usually presumptive (doctors suspect LGV so he/she starts the treatment).
Now it is quite clear.
Why do you think your treatment was a failure? Doxy alone is very effective against early syphilis. In your case you kinda double-covered your syphilis, so I would never suspect a failed treatment.
My point is you should first see the VDRL titers (no sooner than in 2 months) and then you can assess the treatment success.
You asked "is it possible for syphilis to evade 3 shot penicillin/28 day doxy and remain in the central nervous system only to strike back decades later?"
Theoretically, yes. Syphilis is so well studied, that all sorts of treatment failures/late comebacks are documented. But you are about a million times more likely to die from a sudden stroke/heart attack in your early 30s. And about a thousand times more likely to be bitten by a snake or a rabid dog. Can we really cover all the risks?
You asked: "And what harm may the spinal tap cause?"
A missed tap may render you paralyzed for life (risk is very low, though). You will feel sick for a few days and the test results will definitely come negative after all those antibiotics you had. The general principle of medical science is "Anything that is not necessary is harmful". A spinal tap is really not necessary in your case.
I understand what you are asking here - will the doxy make the penicillin less effective, thereby making your treatment a failure?

I don't think so, because your symptoms are getting better, and because doxy is also effective at treating syphilis. We can't ever tell if the doxy is making it less effective - and it can do that, apparently - but if it is, it seems like the doxy will be backing it up, so to speak, in your case, since your symptoms are improving.

I totally agree with grobick about the spinal tap. There is no evidence of neurosyphilis here, and you are getting treatment. The risks outweigh the benefits of such an invasive test.
Avatar universal
Do you think I should ask for a neurosyphilis test as well? Also, should I ask her to repeat the penicillin injections after the doxy course is completed? Yes, TB prevalence is high in India. Not sure about LGV. And when should I test for the titers?
Helpful - 0
Have an Answer?

You are reading content posted in the STDs / STIs Community

Didn't find the answer you were looking for?
Ask a question
Popular Resources
Herpes spreads by oral, vaginal and anal sex.
Herpes sores blister, then burst, scab and heal.
STIs are the most common cause of genital sores.
Millions of people are diagnosed with STDs in the U.S. each year.
STDs can't be transmitted by casual contact, like hugging or touching.
Syphilis is an STD that is transmitted by oral, genital and anal sex.