I have a few questions. First, STI tests have gotten better over the years. Is urine analysis now the standard for many of the STIs that previously required swabbing? Also, it seems that the HIV test is now done almost exclusively with an oral swab or a finger prick, and quick results, as opposed to drawing a vial of blood and waiting. Which is better, the oral swab or the finger prick, and does the accuracy approach that of the blood draw? I did the oral swab when it was new, obtained a result that made me comfortable, and I went again for a blood draw to confirm it. Second, I went to the pharmacy a couple of months ago and saw that they sell HIV home test kits. I thought that having a counselor before and after the test was an important part of testing. What happened that those who oversee this (the FDA or whomever) loosened their position on this to allow self-testing?
from what I have heard, the oral HIV tests are not 100%. However I think they normally have more false positives than negatives. For the oral I think the protocol is that if it comes back negative you should be fine but if it is positive you need a blood test to determine your status. Just keep in mind that with the oral test a positive means get the blood test, you may not be positive but you should limit sexual contact (and be safe with all contact) until you get a blood test to check the results. Again I am not sure this is true of all tests but the ones I have seen all advertise this information.
The test quality has to do not with how the specimen is collected, but the actual test technology. As far as I know, for HIV, the most reliable test is the PCR, but it is very expensive. The less expensive test (I think ELISA is still used) which is near-instant results, is testing antibodies, so while it's accurate if antibodies are present, it takes the body weeks, sometimes months, to make the antibodies after HIV infection. PCR, on the other hand, actually detects virus. The rapid test is about 95% accurate at 30 days after exposure, and about 99% after 3 months, if I remember correctly. I'm less familiar with current tests for other STIs. I know there are instant tests for gonorrhea, chlamydia, syphillis, and hepatitis A, B and C. But I don't think they're widely used in the US.
Yes the antibody test will be positive with 100% accuracy about 3 months after infection. So, you could have been exposed to HIV, even had the primary symptoms and still test negative with the antibody test immediately afterwards. As Chip stated, the polymerized chain reaction (PCR) method, while expensive, will detect the actual virus in the body and not the antibodies that form in reaction to the virus, which take longer to appear (this is called seroconversion). Gonorrhea is normally tested with the first 10 mL of urine (it colonizes the urinary tract so you want the first few drops). There are also oral and rectal swabs, normally done if you are symptomatic. The syphilis and hepatitis tests are done with a standard blood draw. Do ensure you are vaccinated against hep A and B! Most importantly, the non-HIV STDs are just as important to avoid as HIV itself, because their presence significantly increases the risk of catching HIV.
Ok, thanks everybody. And if the rapid tests are 99% effective after 3 months, that's pretty good. GW, I think the urine test would also work for chlamydia. Yes, I agree with the Hep A and Hep B vaccination. I received them ~2000. I've asked for a booster within the recent past and was told that the vaccine is pretty good and actually covers for more than 10 years. Hep A can be obtained from dirty utensils or unsanitary conditions, so it's good to have for traveling where conditions may not be as spic and span, and is independent of sexual transmission. Still, I'm amazed that the home HIV test kits are sitting there on the shelves at chain drug stores. Amazing.
