Q&A: Are Oral HIV Tests Reliable ?
Q: I recently had the oral swab HIV test done. It came back negative, but I’m still worried about whether or not to take a blood test, too – I’ve heard that these oral swab tests can often give false results and may not be as conclusive as a traditional blood screening. The swab test just seemed too fast and easy! Am I worrying for no reason?
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Many of the HIV tests that we use do not directly detect the virus, but actually detect the presence of antibodies to the virus. Antibodies circulate in the blood but are also released into the saliva. The oral tests allow for rapid screening, client education and counseling and referrals for confirmatory tests when necessary.
Yes, the oral test can be incorrect – but so can blood tests. People can test negative when they’re actually positive and vice versa. This seldom happens and both the oral test and the blood tests are highly accurate. You can always request a blood test if you don’t feel comfortable with the results. There is a very low chance that two tests can both be wrong. Individuals who test positive on the oral test are referred to have a blood test for confirmation.
The important concept here is that oral tests and the major blood tests, the Western Blot test and ELISA test, detect antibodies to HIV. The problem is that once a person is infected with HIV, it takes the body several weeks to produce HIV antibodies. During this window, these tests could be negative or “indeterminant” when the person is actually inefcted. One option is to repeat the test in a couple months. If there is indeed an infection, this would allow more time for levels of antibodies to rise enough to be detected with the test.
If you suspect that there may have been an exposure to HIV (unprotected sex , condom break, injection drug use, needle stick, rape, etc.), there is another option – a test for HIV viral load. You see, when a person is infected by HIV through sex or blood exposure, there is an incubation period of several days. Then, the person is likely to experience a clinical syndrome that may include fever, swollen glands, muscle aches, rash, fatigue and malaise. These symptoms appear as the HIV virus begins to reproduce at very high levels. It takes several weeks for the person’s immune system to put the virus in check and produce antibodies. However, before the antibodies develop, there are enormous amounts of virus in the person’s blood. While the standard HIV tests are negative, a test for HIV viral load (HIV RNA by PCR) reveals millions of copies of virus in the blood.
If you have experienced these symptoms or otherwise suspect an exposure, the HIV RNA PCR test would detect lots of virus while the HIV test may still be negative. MANY PHYSICIANS AND NURSES DO NOT KNOW THIS!! If an infected person is detected during this early phase and starts HIV medicines, the drugs can have a profound effect in helping the body’s immune response to control the virus.Discuss these topics with your medical provider and if necessary, seek a referral to a doctor specializing in infectious diseases.