[Question #7111] VIH test

7 months ago
Hello Dr.  I´m writing from Spain. 
20 days ago I had vaginal protected sex with a masseuse and condom didn't break and was in place all the time. Yesterday I had a low fever (38º C) that last just one day, today I have not fever and I fell all right.
Today I did a Elisa 4th generation test and the results were 0,799 NO REACTIVE.
I´m scared of 0,799 results. (Lab said positive is more than 1) 
Have I been at risk and must I repeat the test?
Thank you, Dr.
H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
7 months ago
Bienvenido al foro. Gracias por su confianza en nuestros servicios.

Although I don't know the details of HIV epidemiology in Spain, in most western and industrialized the frequency of HIV in masseuses and female sex workers is low, so most likely your partner didn't have HIV. Even if she did, without a condom, a single epsiode of vaginal sex with an infected woman carries roughly a risk of 1 in 2,500. With a condom, the risk is zero for all practical purposes. Fever alone is not likely a symptom of acute HIV infection. In addition, it started too late:  when acute HIV infecction causes symptoms, they usually occur 7-14 days after infetion; 20 days is too long.

The ELISA ratio you describe is definitely negative. Any value under 0.9 (or 1.0, depending on the particular test) is equally negative. For example, there is no difference in meaing between, say, 0.2, 0.5, or 0.8; all are equally negative. In fact, the same sample tested 10 times might give 10 widely different numbers.

Twenty days after infection, around 80-90% of newlyl infected people have positive results with the Ag/Ab (4th generation) HIV blood tests. You can test again at 4 weeks (98% reliability) or 6 weeks for a 100% conclusive result. Almost certainly these additional results will also be negative.

Feel free to return to let me know the results if you are retested. In the meantime, do your best to relax and not worry. Almost certainly you do not have HIV. 

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

HHH, MD
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7 months ago
Just curiosity : If test meassure Ab, I supose That the number under 1 mind a little amount of hiv Antibodies... Why they are not take in consideration?
Sorry about my English, and thak you again.
H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
7 months ago
The biochemistry of the test is not what you think. The number does not indicate the amount of antibody present. Having a "little amount" of antibody makes no difference in the number, as long as it is below 1.0.---
7 months ago
Thank you Dr.
I deduce from your words: "Condom is risk zero for all practical pourposes" and for all the things you said in your answer, that retesting is not necesary.   
If I where your patient would you recommended me to retest?
H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
7 months ago
Yes, I would recommend another test. NOT because I believe there is any signficant chance you were infected; only for reassurance. Having been tested once but too early, it makes sense to be tested after enough time for a conclusive result. Otherewise, you probably will continue to worry:  anxious persons often are more reassured by negative test results than by professional opinion, no matter how expert. However, this is entirely up to you. I I were personally in your situation, I would not have been tested at all.

My final advice is that you consider being tested for COVID-19. In the current pandemic, COVID is a far more likely cause of low grade fever (38C) than HIV.

That concludes the two follow-up exchanges included with each question, and so ends this discussion. I hope it has been helpful and reassuring. Mis mejores deseos y mantente seguro.
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