[Question #6629] Hiv test accurate? Medication interference?

12 months ago

Hello,

Thank you for the service here.

So, back in Early July 2019, I had an instance where I gave unprotected fellatio to 2 men. There was no ejaculate in my mouth, and there might have been precum. No sexual exposure since. I don’t use drugs either.

Around 10 days after this encounter, I had a rapid test and a 4th gen lab test done for hiv (For a previous unrelated encounter that occurred months before) and the tests were non reactive.

Knowing about the window period, I finally got tested in January 2020 for hiv:

On January 22 I took a rapid insti test at a clinic: Non Reactive.

Decided to Repeat another insti test a week later: Non Reactive.

Finally, on January 31 I had a vein blood test (4th gen I believe) taken for both HIV and Syphilis and sent to a lab: Non reactive.

I know typically these results are conclusive.

However, from December 2019-January 18 2020, I was visiting a south Asian country where I had an ongoing cold/sore throat/congestion. The doctor there prescribed me a whole bunch of different medications. I didn’t take many of them as I didn’t really feel like I needed all this medicine, since my Canadian doctor typically never prescribes me anything for similar symptoms.

I was looking at the prescription today, and noticed I was prescribed Prednisolone (it says prednisolone 5). I don’t remember if I actually took it or not.

But let’s assume that from Early January - maybe January 18, I took this medication along with other cough syrups/allergy pills. Could it have affected the hiv tests I took once I returned to Canada?

Could the prednisolone have suppressed my immune system and lowered the antibodies I had developed in the past 6 months since the July encounter? Making the test Incorrect?

I read that medication like Prednisolone can affect hiv tests, but is that only if you take the medication before you ever develop antibodies?

Should I need to retest for hiv and syphilis due to this? Also This is the first time I tested for syphilis, so it might have a higher risk right?

Also, I did also take reactine before the test as well.

Thank you.

H. Hunter Handsfield, MD

12 months ago

Welcome to the forum. Thanks for your confidence in our services.

You can relax. It is 100% certain you don't have HIV or syphilis. Indeed, you have been seriously overtested. You had virtually zero risk exposures, and several of the tests you describe were conclusive. Immune suppressive therapy like prednisolone does not affect the modern HIV tests; that's an urban myth left over from older tests not in use for over 10-15 years. Even then, it took far more potent immune suppression to have any effect. In fact, being immunosuppressed actually increases the speed and likely positive results with the AgAb (4th generation) blood tests. Suppressing antibody would make the antigen component (the Ag of the AgAb test) more strongly positive.

The same is true of syphilis blood tests: low risk exposure and conclusive test results.

So all is well. You can be sure you have neither HIV nor sypohilis. You don't need any more tests.

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

HHH, MD

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12 months ago

Thank you so much for the reply!

It is good to hear that you believe I need no further testing.

Just some more clarification questions.

So the prednisolone wouldn’t have affected the potential existing hiv antibodies at all? And in the case that it did decrease my antibody levels, wouldn’t the test be too early to catch the re-emergence of the Hiv p24 antigen after the potential antibodies decrease in January? I read that p24 antigen takes about 4-8 weeks to be produced at detectable levels. And if I finished medication on the 18th, that would only be around 2 weeks.

Even if I only had taken the insti tests, would you still consider it conclusively negative?

Also, just for knowledge, is giving unprotected oral to a male actually a risk? The Internet is all over the place with some saying no risk, others like Dr Hook saying on here that there have been cases, but still low risk.

Thank you so much!

H. Hunter Handsfield, MD

12 months ago

Good questions; happy to clarify.

The internet claims about corticosteroids (like prednisolone) and other immune suppressive drugs on antibody production are wildly inaccurate. It's simply a non-problem, for HIV testing or any other antibody testing, at least at the doses and durations of treatment used 99% of the time. You also have misread or misunderstood the details of the AgAb tests and how they work, and/or about the physiology of new HIV infections. p24 Ag appears starting 10-14 days after infection and is pretty much always present by 4 weeks. Antibody (Ab) follows soon thereafter. It is the antibody that clears p24 from the blood. Therefore, once the AgAb test becomes positive -- i.e. detection of p 24 Ag initially, then a brief period when both p24 and antibody are both detectable, then antibody alone (having cleared out the antigen) -- the test is positive for life. There are no exceptions, and no medical treatment or disease of any kind, including potent immunosuppression, can make the test falsely negative. It simply never happens.

There is no conflict between those statements about penile to oral HIV transmission by fellatio. CDC has estimated a risk of 1 chance in 10,000 when performing fellatio on an HIV infected male partner, equivalent to giving BJs to infected men once daily fro 27 years before transmission might be likely. It's logical that casual advice might equate that with zero risk, although ideally one might expect a clarification like "zero for all practical purposes".

And yes, INSTI alone would have been conclusive, again perhaps "for all practical purposes". If that test were, say, "only" 99% sensitive, after an exposure with risk of 1 in 10,000, the chance that person would have HIV after a negative test result would be 1 in a million (0.0001 x 0.01 = 0.000001). I hope you would consider that zero! I certainly would if somehow I were in that situation.

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12 months ago

Thank you once again!

So in conclusion, it would seem that I would have developed antibodies around 6-12 weeks after my exposure in July 2019, and so the medication (prednisolone/prednisone) I took in December 2019 would have had no affect on my already existing antibodies, since once formed, antibodies are always detected no matter what? All in all, making the tests I took January 2020 correct and conclusive.

Is my understanding correct?

I really just want to move on from this and feel safe knowing I don’t have hiv from the July encounter.

One more question, let’s say anxiety gets the better of me and I retest just for peace of mind, would I hypothetically need to wait any amount of time? I read that post-pep guidelines are to wait 3-6 months after completion of pep. I know my medication is not at all similar to pep, but both might hypothetically affect testing right.

I really do apologize for all the extra questions. Just trying to get a whole picture here, and clear my mind of any doubts. I’ve followed your work since medhelp and appreciate all the great answers you give.

Thank you once again!

H. Hunter Handsfield, MD

12 months ago

Yes, your understanding is correct. Except you would have developed antibodies before 6 weeks, not 6-12 weeks. And once present, they are there forever and immunosuppression would not change that. Also see my comments that you didn't receive nearly enough prednisolone to have any effect on antibody production. And if somehow you did, your test would still be positive because of the p24 antigen (which would reappear in blood if somehow antibody waned).

Feel free to test again if and when you want. It's your money. Timing doesn't matter.

Please don't challenge the science: it is rock solid on all this. It's time for you to accept the truth and the reasoned, science based reassurance -- which presumably is why you came to the forum. Do your best to move on.

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