[Question #3016] Testing

92 months ago

Dr's

I had an possible exposure 3 years ago, protected sex with prostitute, and did 4th generation test at 20 days, 29 days and 60 days and all cam back negative. I had another potential exposure last April, 2017, when a stripper fingered herself and stuck it in my mouth. I believe these are both low risk events but I want to see how reliable my testing is. I did a 4th generation test recently at the 6 month time frame for the most recent situation and it came back negative. Can you let me know how reliable the 4th generation tests are in my case this far out for both exposures? I have been having a long lasting cough and body aches and want to be sure that these negative tests mean I do not have HIV. Please let me know your thoughts and if there is a test you recommend other than what I have taken to give me a more accurate result? I did my testing through a nationally known discrete company that uses nationally reputable labs, want to make sure I am negative for HIV with the testing I have done to date. Thanks you!

H. Hunter Handsfield, MD

92 months ago

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

The HIV blood tests are among the most accurate diagnostic tests ever developed, for any medical condition. The results are 100% conclusive once enough time has passed after the last possible exposure. With the current tests in routine use, i.e. the moder standalone HIV antibody tests and the antigen-antibody ("4th generation") tests, that time is 6 weeks. Negative results after that time overrule all other considerations: no matter how high the risk at the time of exposure and no matter what sympsoms someone may have, negative testing shows the person was not infected with HIV. And you had obviously low risk exposures, and HIV doesn't cause symptoms like yours -- it's not a cause of cough, for example.

Test reliability is the same no matter where it is done or in what laboratory: the same test are done in all labs, and they are highly automated, with no realistic chance of error in their performance.

So your negative tests were done well past those times and are 100% conclusive. You do not need any further tests. See your doctor about your symptoms if they continue and/or if you remain concerned about them.

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

HHH, MD

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92 months ago

My concern is that the testing facility is telling me my test is only 99% accurate, obviously I will take your advice, but I am concerned as to why they would say 99% and they state that clinicians recommend retesting to be accurate, what are your thoughts? I have also heard that some people do not form antibodies to fight HIV and therefore would test negative, while actually having the disease, can you let me know if this is true? Is there any other test you would recommend or do I move forward with confidence?

Thanks,

H. Hunter Handsfield, MD

92 months ago

First, failure to form antibodies is irrelevant: it rarely if ever happens, but the test still would be positive. It detects both HIV antigen and antibody, and if antibody is absent, antigen is always detectable. Official statistics on reliability, as the FDA permits test manufacturers to state, say 99%. However, 100% probably is indeed valid: in the 10+ years of the current 3rd and 4th generation tests, no HIV experts have seen any patients who did not develop positive tests.

And so what if the test were "only" 99% senstiive? Let's analyze the statistics. Chance either of your CSW partners had HIV, 1% tops (1 in 100). If the first had HIV, chance of transmission by unprotected vaginal sex averages about one in 2,000. That's reduced by 99% by using a condom. So even before you were tested, the odds you caught HIV from the first event were 0.01 x 0.005 x 0.01 = 0.0000005. That's one chance in 2 million. Now apply a test that is 99% valid, and the odds you have HIV become 1 in 200 miillion, which obviously is zero for all practical purposes. The second event was even less risky: it is very rare to get HIV by oral exposure to vaginal fluids, if it occurs at all. There has never been a reported case of catching it by oral-vaginal exposure, and the exposure to vaginal fluids by finger transfer is even lower (if you can get lower than 0% chance).

So let this go. Have no more tests and stop searching online about it. Say nothing to future partners. Move on with your life without worry.

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92 months ago

Thank you Dr. A couple questions, I was of the understanding that the Antigen is only present for a short period of time and with the time that has passed in my situations, that it would not be detectable? Is that not the case? Also to clarify your first paragraph that in 10 years do you mean that experts have not seen someone who was positive for HIV, not test positive with the 3rd and 4th Gen tests in the time frame that I am dealing with of 5 months+? Thank you and have a great day!

H. Hunter Handsfield, MD

92 months ago

You misunderstand the physiology and the biology of the duo test. Antigen normally is present only a short time because it is the antibody that clears antigen from the blood. Antigen persists until soon after antibody appears. If antibody doesn't develop, antigen continues to circulatein the blood. I have never seen any infected person with negative duo or third gen HIV test results later than 4 weeks after exposure.

That concludes the two follow-up comments and replies included with each question and so finishes this thread. Take care and stay safe -- and don't give any of these issues another thought. There is no chance you have HIV.

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