Q: This is regarding an AIDS test. Which type of test should I undergo? I have been advised for ELISA. Should I go for this or is there anything else simple? I had gone out one night and met this decent looking girl, she came with me and we had sex. While having sex, I used the safety precautions but the condom tore and I realised this only after 10 to 15 minutes and so we stopped. Now, I am worried and thinking as to what should I do? Please suggest the best test?

A:The ELISA detects HIV antibodies in the serum/plasma samples. The antibodies appear 8 to 12 weeks after the exposure with the virus by any route of infection and thereafter remain life long. This period of absence of antibodies in serum/plasma after acquiring infection is called Window period. ELISA or other antibody tests fail to detect HIV infection during this period. The infected individual is also highly infectious during this period. Only test commercially available is detection of HIV proviral DNA in the peripheral blood lymphocytes (that is circulating white blood cells) by PCR assay (or a more sensitive Real-time PCR assay). In some infected individuals antibodies may not appear even after 12 weeks. In such cases it is advisable to conduct ELISA every 3 months for one year after the last sexual intercourse before declaring him/her negative for HIV. However, in such individuals, test for proviral DNA is advisable. Since you have had unprotected casual sexual intercourse 9 weeks ago, I suggest that you should go in for the detection of HIV proviral DNA by PCR/Real time PCR assay.