Q: How reliable is a DNA PCR test and after how long should it be done? I had an encounter with a prostitute without condoms about 4 months back. I got a DNA PCR test after 50 days at SRL Ranbaxy Lab, which was negative.

A:HIV PCR test is the most sensitive test for diagnosing HIV infection and is very sensitive in case detection even in the window period, during which the antibody ELISA test is negative. After the window phase, the ELISA test for HIV antibodies is also quite sensitive. Instead of worrying over this issue, safe sexual practices in future are recommended. And as they say, prevention is better than cure.