The reason you actually want to do an HIV test LKD is so that you can stop worrying and rest assured.
Another reason is early detection can make treatment much more successful.
BTW there are different tests for HIV, including antibody, p24 antigen, NAT, etc
The Health Nurse commented on the subject of the NAT test for HIV:
"The HIV DNA PCR (NAAT test) 90% of people would test positive by 10-12 days after being infected and 95-98% of people would test positive 4-6 weeks after being infected."
https://perb.cc/vbulletin/showthread.php?134988-HIV-Symtoms-Worries&highlight=antigen
Various numbers are given by differing sources, the earliest being 5 days after an infection to detect HIV:
"Nucleic Acid Amplification Testing (NAT) is the newest technology available at Anonymous Clinic to determine your HIV status after only 5 days of possible exposure to the infection. New, safe and extremely accurate, with NAT you can now know your status much earlier, shortening the window period between the infection and detectability of disease."
"...HIV can be detected on after only 5 days of exposure, average 2 weeks..."
http://www.adamslove.org/en-d.php?id=70
"It is now possible to diagnose HIV infection within the first 3 weeks of onset using nucleic acid testing (NAT).5"
http://journals.lww.com/jaids/Fullt...ce_and_Characterization_of_Acute_HIV_1.6.aspx
http://www.ncbi.nlm.nih.gov/pubmed/15872202
"For HIV-1, the average window period with antibody is 22 days. This window period is reduced approximately to 16 days with antigen testing and to 12 days with NAT."
http://www.thebody.com/content/art13891.html?ic=800101
"Since routine HIV antibody tests yield negative results during the first four to five weeks of HIV infection,6 acute infections can be diagnosed during this period only with the use of tests for viral antigens, nucleic acids, or both.
http://www.nejm.org/doi/full/10.1056/NEJMoa042291
NAT testing is also used to help stop HIV infected blood from blood donors being used for transfusions:
"He credits the use of nucleic acid testing for reducing the window of detection to just a few days following infection. The United States has virtually eliminated HIV infected blood from the blood supply. And what about the next 5 to 10 years? “I sincerely hope that we will see a cure, a vaccine, or both,” says George."
Then there is the p24 antigen test for HIV which is covered by BC health care:
"The p24 antigen test detects actual HIV viral protein in blood. The test is generally positive from about one week to 3-4 weeks after infection with HIV.
http://labtestsonline.org/understanding/analytes/p24/tab/test
"Fourth generation tests
"Some of the most modern HIV tests combine P24 antigen tests with standard antibody tests to reduce the ‘diagnostic window’. Testing for antibodies and P24 antigen simultaneously has the advantage of enabling earlier and more accurate HIV detection.
"In the UK, fourth generation tests are the primary recommendation for HIV testing among individuals, but are not offered by all testing sites.1 During June 2010, the FDA approved the first fourth generation test in the United States.2"
http://www.avert.org/testing.htm
These tests are useful to identify an infection of HIV in the early "acute" stage of HIV so it can be treated more effetively and when it is the most infectious.
"...the HIV antibody test will not detect a recently infected donor, so some blood banks use a p24 antigen or HIV nucleic acid test in addition to the basic antibody test to detect infected donors during that period."
http://en.wikipedia.org/wiki/Blood_donation
"The availability of nucleic acid tests (NAT), which reduces the window period and makes testing much more accurate, helped to support the argument for a change in the ban against MSM donating. These tests have been found to almost eliminate the possibility that HIV infected blood will pass through the testing stage, even in countries with high prevalence.33"
http://www.avert.org/blood-safety-hiv.htm