How reliable is a HIV ELISA Test and a Western Blot?

When I was 15 yrs I was sexually abused. When I turned 20yrs I took 2 HIV Elisa tests 5 months apart and they both came back negative. Now that I am 22yrs I took another HIV test and it read Positive for HIV 1 and 2. How can this be? My doctor has sent me for a Western Blot so I am now awaiting results which I fear because after this incident since I was 15, I have lost a lot of weight and cannot gain any. I was 135 lbs, and now I am 87 lbs. Please help. Let me know why after 5 yrs my results were negative and now 2yrs after it is positive.

Since the ELISA test is the first test used to check for HIV, it is important that it pick up everybody that has the virus. For this reason, it has been designed to be overly sensitive. Many people have positive ELISA tests, and turn out not to have HIV. While I'm not saying don't worry about it at all, a positive ELISA test doesn't mean you have HIV. This is why a Western Blot is used as a follow up. Wait until you get your Western Blot results back to worry yourself sick. (I know that's easier said than done though.)

HIV tests don't detect the HIV virus itself. They detect antibodies that the body makes in response to infection by the virus. It takes the body about 3 to 6 months to form the antibodies - when means the tests don't really reflect anything that happened in the 6 months prior. Since there was a period of 5 years between the incidence of sexual abuse and you HIV tests, I don't think this is cause for you to be concerned.

The important thing for you to ask yourself is if there have been any other incidences where you might have been exposed to the virus, such as unprotected sex, contact with another person's blood, IV drug use, etc. There are a lot of reasons other than HIV that you could have difficulty gaining weight.

I wish you the best of luck and hope everything turns out well for you!

The tests are pretty accurate. I just recently read online that the ELISA tests are like 99.7 to 99.8 percent effective. Only thing I can think of is that you took the test to early after being abused. Did you have unproctected sex from age 20 to 22? All it takes is one time- the guy doesn't even have to have an orgasm inside of you. Or even the condom breaking of a partner that was poz and didn't tell you about it. You have go back and think about all possible partners you had sex with from 20 yrs old to 22. Pre-ejaculate fluid carries the virus and if you had any tearing inside, you are more than likely to contract it. Weightloss that you have described is typical for an HIV positive person. Someone I was with for 2 yrs lost weight all the time and it scared me.

Well if you were free of hiv and have not had sex you are safe, but you could of caught it some way. Let me tell you something wouldnt you rather know if you have it or not.
I am going to be honest with you I dont have it, and dont want to ever get it, but if you know you have it you can get treatment.

If you did drugs,had sex even with a condom you can get it.
Be safe
I doubt you have it though

Together, the ELISA and Western Blot are very reliable, but by itself a positive ELISA does not mean you have HIV.

If an ELISA test reads negative it is very reliable, provided it is done more than 13 weeks after the exposure. If you had a negative HIV test 5 months after the assault you can be extremely confident you did not acquire HIV then.

However you cannot determine whether you have HIV on a positive ELISA alone. The majority of positive ELISA tests done in the US are false positives. You cannot identify that you have HIV unless you do both the ELISA and the Western Blot.

If the Western Blot comes up negative (and I expect it will unless you have picked up HIV some months AFTER the assault), you will need to repeat it.

This is how to interpret the tests:

Negative ELISA alone = negative for HIV with an excellent degree of certainty.
Positive ELISA alone = can't say, need further tests
Positive ELISA + negative Western Blot = reassuring, but need to repeat the test to be sure.
Positive ELISA + negative Western Blot + another negative Western Blot 2-4 weeks later = negative for HIV with an excellent degree of certainty.
Positive ELISA + positive Western Blot = positive for HIV, but usually need to do a repeat test to confirm.

Hope that helps.