HIV Testing

Though there are a number of diagnostic tests used to detect HIV infection the most commonly used are the ELISA and Western blot antibody tests. ELISA stands for Enzyme linked immunosorbent assay. Used for blood screening, it is relatively inexpensive and easy to perform. It should always be followed by a Western blot assay which is used to independently confirm a positive ELISA test. The independent confirmation of the Western blot assay is needed because there can be false positives from the ELISA test, though this is rare.

There are several reasons why a false positive from the ELISA test might occur if the patient being tested:

Also there could be:

For this reason the test of diagnosis is the Western blot -- an extremely sensitive and conclusive test that consists of protein bands which indicate the presence of HIV. Sometimes another supplemental test -- the immunofluorescence assay (IFA) -- is used.

A positive antibody test -- confirmed by a supplementary test -- means a patient is infected with HIV. What the test does not indicate is when the initial infection occurred, the measure of host immunity or the life expectancy of the patient. The test is designed to detect the presence of HIV infection, and is not diagnostic of AIDS.

Although a negative antibody test usually means a patient is not infected with HIV, the test cannot be relied upon to rule out HIV infection that occurred in a patient up to six months previous to the test. This is called a "window of opportunity" or "window period" and can result in a false negative test result. HIV antibody will be detected in 95% of patients within 6 months after the initial infection, but the average time for antibodies to be able to be detected is only 2 months. Also, since HIV antibody crosses the placenta, its presence in a child under 18 months does not necessarily confirm HIV infection.

So we can see that though the ELISA and Western blot tests are reliable, effective methods for diagnosing HIV infection, there are cases where false positive and false negative results can occur. That is why an ongoing and information-sharing relationship with your health care provider is important. A patient's unique health history and behavior needs to be evaluated by a health care provider experienced in the testing and diagnosis of HIV.

While there are compelling reasons and great benefits for patients to have an HIV test, especially for those whose behavior has put them at risk, the entire testing process is sensitive, with a number of important considerations to be addressed.

There are certain times when an HIV test is not indicated and it would even go against standard medical practice to administer one. You should not be tested for HIV when pre- or post-test counseling is not available. Informed consent must be obtained before an HIV test is performed. (Some states require written consent.) Part of pretest counseling, informed consent provides you with the basic knowledge of what type of permission you are giving, to whom you are giving it, and what will be done with the test results. Informed consent should explain to you all of the consequences, good or bad, of the entire testing process, should thoroughly explain the difference between anonymity and confidentiality, where you can go for post-test follow-up care and what the consequences could be for choosing to be or not to be tested. Certainly a patient who does not have a support system in place or who has an emotional or psychiatric disturbance, or who may be suicidal should not be tested. Insist upon counseling so that you may obtain accurate and detailed information about the test, your potential risk factors, and about HIV disease itself. This is an excellent time to have any questions about HIV testing answered and hopefully an opportunity to lessen your fears or anxieties. If you have been given an HIV test without pre- or post-test counseling, truly you have had a disservice done.

Having given reasons why certain patients should refrain from having an HIV test, it must be said that under the proper clinical conditions, with pre- and post-test counseling in place, there are great benefits for most patients in having an HIV antibody test. These can include:

Remember -- pre-test and post-test counseling is part of -- not separate from -- the testing procedure. Your health care provider will want to evaluate you face to face -- this is beneficial not only for assessment of your personal health risks and for the dissemination of information but your health care provider may also see specific symptoms that are important in your individual diagnosis. Your health care provider should be experienced in recognizing those patients who fit into high or higher risk groups. These groups include:

Recently home testing has become available, is being used and yields extremely accurate results. However there are grave concerns about the circumstances in which those who -- through home testing -- find out their HIV status. It is thought that HIV always, varying in length of time from patient to patient, leads to AIDS, a terminal disease. Home testing provides no emotional support or health care teaching -- there is no face to face interaction between patient and HIV educator. You thus could learn that you have a virus that will lead to a terminal illness while sitting alone in your home. You could be genuinely shocked that you are infected with HIV or somehow expecting the confirmation that you have been infected by this dreaded disease -- either way it leaves something to be desired to find you have a positive test result without the presence of an experienced professional HIV educator or without the benefit of immediate emotional support.

Likewise, positive counseling advises against revealing HIV test results over the phone for the same reasons. Additionally, mistakes can be made via the telephone, such as the test results could be given to someone other than the person who was tested. Positive test results must be given face to face as part of the post-test counseling process.

Benefits of this post counseling session include:

Also, if you are diagnosed with a sexually transmitted disease such as syphilis, gonorrhea, chlamydia, hepatitis B or herpes, a discussion about HIV testing and counseling is very important and indicated. When a person has at least one sexually transmitted disease, studies have shown that the risk for HIV transmission is much more likely. This is thought to be due to the body's altered defense mechanism when it is infected with an STD.

Should you suspect that you might have been infected with HIV or that you are in a high risk group for contracting HIV and wish to be tested, please see your health care provider promptly to discuss this important matter.