[Question #12663] testing questions and rash

6 months ago

Hello Drs!

1) does taking oral antihistamines have any effect on blood tests for HIV, Syphilis, HSV or urine tests for any. I have a full std panel tomorrow and have been taking anti histamines the last 3 days including this morning.

2) I’ve developed a rash which started on stomach, arms and inner thighs that eventually spread to penis too. Dermatologist said it was Pityriasis Rosea but advised testing for syphilis to rule it out. I tested negative for syphilis over 6 months after any possible encounter with someone of unknown status. I also tested negative at 8 weeks, 12 weeks after encounter.

Thanks!

6 months ago

3) finally hsv 1/2. The rash doesn’t look like hsv blisters but the dermatologist did not see the ones on penis as they appeared after appointment. Previously tested negative for hsv blood at 8 weeks post frottage which was 18 months ago.

H. Hunter Handsfield, MD

6 months ago

Welcome back to the forum. Thank you for your continued confidence in our services.

You don't describe a new exposure. It seem you are referring to the one described in your previous question a year ago? If so, your negative tests back then showed your current rash could not have been syphilis.

1) So it sounds like both the earlier and more recent blood work was plenty long enough for any and all syphilis and HIV tests to be conclusively reliable. Antihistamines do not affect the reliability or timing of any of the tests you had. In fact, NO drugs do that for HIV, sphilis, or HSV except for the drugs used to treat them. Presumably having not taken antbiotics active against syphilis or any anti-herpetic or anti-HIV drugs, your test results are reliable.

2) Pityriasis rosea is widely recognized as a condition that can closely resembe the rash of secondary syphilis, so the dermatologist was right and proper to recommend the syphilis blood test. The negative result proves absolutely you do not have syphilis.

3) Herpes does not remotely resemble either secondary syphilis or pityriasis rosea. Your previous negative HSV blood test was fairly reliable although in itself not conclusive; it takes up to 12 weeks for HSV antibodies to be detectable. OTOH, as discussed last time, you were not at measurable risk of herpes during the event described last time. There is no possibility herpes explains any part of your rash, regardless of genital involvement (if any).

I hope these comments are helpful. Let me know if anything isn't clear.

HHH, MD

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6 months ago

Thank you for your informative response as always!

As part of the panel today there is an HSV blood test which I think tests IGG. I know you said that it’s very very unlikely this rash is HSV but if it was, would an IGG test pick it up while the rash is ongoing?

Again, the marks on the penis, which are quite numerous to be honest (lots of various mostly disconnected red marks) are not blistering and definitely do resemble the spots on the rest of my abdomen but can’t shake the thought of HSV at the moment !

Thanks again!

H. Hunter Handsfield, MD

6 months ago

once the HSV blood tests are positive, they remain positive for life. Whether a test is positive or negative, or the strength of a positive result, has nothing at all to do with whether the infection is "active" (causing symptoms or "ongoing").

I can't help that you "can't shake the thought of HSV at the moment". It's nonsense. Do you somehow think that any kinds of "marks on the penis" must be herpes? That's dumb. You can believe the science or not, I don't care: but it is BS that you are concerned about herpes. Sorry to be so blunt -- but suck it up!

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6 months ago

Hahah very well said! I feel like sucking it up is probably the best way to go.

Just final confirmation - given it’s been 18 months since any sort of exposure with unknown person. An HSV IGG test taken would be quite reliable at this stage ?

I trust the dermatologists opinion but just want to learn about the reliability of the HSV test.

Thanks for the information and for the no nonsense approach! :)

6 months ago

So turns out the test I did for HSV 1/2 was actually a urine PCR test. I assume this is not nearly as reliable as a blood IGG.

Given the dermatologists initial diagnosis of rosea and the fact that the spots haven’t turned into blisters for 3/4 days now. You’d still say HSV was unlikely?

H. Hunter Handsfield, MD

6 months ago

The HSV blood tests often are unreliable regardless of time since exposure. There is a fairly high rate of false positive results, usually in the forum of weakly positive results that may or may not indicate actual infection. If you're in the lucky group with a clean negative HSV2 result, it will be conclusive. Just be prepared for possible uncertainty. The PCR test only detects active viral shedding, which occurs only intermittently; a negative result never reliably excludes herpes.

A dermatologist's diagnosis if p rosea is highly reliable, and there isn't the slightest reason to suspect you have either syphilis or HSV. Let it go.

That concludes this thread. Note the forum policy against repeated anxiety driven questions. This will have to be your last about your exposure a year ago and your subsequent concerns about HSV and syphilis; any more may be deleted without reply and without refund of the posting fee. However, if you test for herpes and have anything other than a negative result for HSV2, Terri would be happy to address next steps to work things out. In the meantime, best wishes and stay safe.

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