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PCR Quantitative Test after 7 days

Jan 2, 2009

Hello Doctor,

Five weeks ago, I performed oral sex on a male who I later found out was HIV+ but had a low viral load. There was no ejaculation, but there certainly was some precum involved. We moved on to perform anal sex, during which I was the insertive member; I wore a condom, but as I started penetration the condom broke. I immediately removed the penis off his rectum and went to wash my penis. Then, using a different condom, we continued.

48 hours later, as I found out this guy was HIV+, I went to talk to an Infectious Disease specialist, who put me on NOPEP (Tenofovir and Combivir). On day 7 after exposure, a quantitative PCR test was performed, which came back negative, as did the P24 Antigen test.

My question is: (1)What are the odds that I'll become HIV+; and (2) How reliable is a negative PCR test 7 days after my exposure?

Thank you for your time and patience.

Response from Dr. Frascino


Your HIV-acquisition risk is unprotected oral sex and brief unprotected (broken condom) insertive anal sex with an HIV-positive buddy. Non-occupational PEP (nPEP) begun 48 hours after exposure will decrease your HIV-acquisition risk. To specifically answer your questions:

1. The estimated per-act risk for acquiring HIV from unprotected receptive oral sex and unprotected insertive anal sex with a partner confirmed to be HIV positive is 1 and 6.5 per 10,000 exposures respectively. Your estimated risk would be less because your anal sex exposure was brief and you are taking nPEP.

2. Not reliable. Viral load testing (PCR RNA) while on antiretrovirals (nPEP) is not a reliable screen for HIV. You could be HIV infected and the antiretrovirals could be suppressing the virus to "undetectable" levels thereby giving a "false-negative" result. PCR RNA testing should not be used for HIV-diagnostic screening, particularly while someone is taking antiretrovirals! I would suggest you follow the nPEP guidelines for testing: HIV-antibody testing at baseline, six weeks, three months and six months. You can read much more about this in the archives.

Good luck.

Dr. Bob

Continuation of Houston HIV care...
Thanks and WOO-HOO

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