Q: I had done a HIV PCR test after 5 days of possible exposure. it was < 50 copies per ml and it was an amplicor ultrasensitive PCR test. Is 5 days long enough for PCR to detect the virus in the blood? 2) it ws a low risk encounter and now its almost 2 months of this incident i have no symptoms so does no symptoms at all a very good sign??

A:There can be no hard and fast exact figure. Generally 5 days should be enough for the virus to replicate enough to be detectable (virus, not antibodies) but I would be happier a few days later. The absence of symptoms does not mean anything and one should put no reliance in that. Except for a relatively minor flue like symptom about a week after infection, HIV infection does not manifest as any symptoms for a long time -- generally many years. Avoid casual sex and if you can not avoid casual sexual exposure, take precautions and practice safer sex