|HIV prevention testing product 'AWARE ORAL'
Jan 23, 2010
Hi Doctor, I am from Hong Kong and I made I think 2 donations previously to your foundation. Now I have a question. There is an advertisement in some peroidicals there is such a product called 'AWARE ORAL'. It claims that it can be used for testing HIV+ simply from saliva. That is one just put on the small piece of testsheet with one's saliva. It claims it has an accuracy rate of 99.8% and is endorsed by an 'USAID' institution (www.usaid.gov). the selling agent's website is www.DiagnosticBio.com . Do you have information, and can it be used in USA and do you think it is reliable? CC from Hong Kong
| Response from Dr. Frascino
Saliva tests have been available for some time; however, they are not FDA approved for use in the U.S. I have no personal experience with AWARE ORAL. There was some concern about a high rate of false positives using saliva tests. Personally I would prefer to use ELISA tests or rapid tests. (See below).
Thanks for your donations to The Robert James Frascino AIDS Foundation. They are warmly appreciated.
HIV Antibody Tests (HIV inSITE)
Generally referred to as ELISA (enzyme-linked immunosorbent assay) or, alternatively, EIA (enzyme immunoassay), these tests detect HIV antibodies, which the body starts producing between 2 and 12 weeks after becoming infected with HIV. This is why experts recommend that you wait to take an antibody test until 3 months (12 weeks) after an incident (such as unprotected sex) that may have led to HIV infection. This recommendation may be changing, as the latest generation of tests is more sensitive than previous ones and can detect HIV antibodies about 2 to 6 weeks after infection. Antibody tests may use any of 3 body fluids to detect antibodies to HIV. These include:
Blood: Drawn from a vein, blood samples are the most common screening method for detecting the presence of HIV antibodies. A test that returns a positive result is confirmed with a follow-up test such as the Western blot before the client is informed of the results (see "HIV Antibody Confirmation Tests" below). Oral Fluid: This test uses oral fluid (not saliva) to detect HIV antibodies in cells found in the mouth along the cheeks and gums. Its reliability is similar to that of the blood test. The fluid is absorbed by a small device (about half the size of a toothbrush), which is held between the cheek and gums for a few minutes and then sent to a lab for processing. Positive results must be confirmed with a Western blot. There is often much confusion about this test because people mistakenly believe that HIV is transmitted through oral fluids and saliva, which is not the case. Like all ELISA tests, oral tests detect antibodies, not HIV itself. Urine: This test uses a urine sample to detect HIV antibodies (again, not the virus itself) in urine. The accuracy of urine tests is somewhat less than that of blood and oral fluid tests. Positive results must be confirmed with a Western blot.
Results from most ELISA tests and confirmatory Western blot tests are usually available 2 to 14 days later.
Rapid HIV Test
Using technology similar to that of an ELISA, a rapid test produces results in approximately 20 minutes. Two types of rapid tests are available now. One uses blood; in this case, a clinician pricks your finger with a small needle and takes a few drops of your blood. The other uses oral fluids and is very similar to the oral fluid test described above. There are two possible outcomes with this test: negative (meaning that the test does not detect any HIV antibodies) or "preliminary positive." In the case of preliminary positive, the rapid HIV test shows an HIV-positive result, but, as with the ELISA test, that result must be confirmed with a second test such as a Western blot. If the result is preliminary positive, the counselor will discuss what this means with the client, including the importance of practicing safer sex and taking other precautions until the confirmation test results come back, and will schedule a time for the client to receive confirmatory results and additional counseling.
HIV Antibody Confirmation Tests
The ELISA test is designed to be highly sensitive, that is, to miss as few HIV infections as possible. The downside of the high sensitivity is that the ELISA may produce a small number of false-positive tests. This usually is due to the presence of antibodies to other diseases that the ELISA mistakenly recognizes as antibodies to HIV. For this reason, it is important to supplement a positive ELISA with a confirmatory test, such as a Western blot, that is less sensitive but more specific, that is, one that has a lower rate of producing a false-positive result.
The Western blot is the most common test used to confirm positive results from an ELISA or rapid HIV test. It generally is used only as a confirmatory test because it is difficult to perform and requires highly technical skills. Its advantage, however, is that it is less likely to give a false-positive result because it can more effectively distinguish HIV antibodies from other antibodies. However, the Western blot can produce inconclusive results in some samples.
Indirect Fluorescent Antibody (IFA)
The indirect fluorescent antibody (IFA) test also detects antibodies made to fight an HIV infection. As with the Western blot, the IFA test is used to confirm the results of an ELISA. However, it is more expensive than a Western blot test.
HIV Viral Load Measurements
You will likely hear this test called a "viral load," "PCR," or "RNA" test. In the public health community, it is also referred to as HIV NAAT (nucleic acid amplification testing). The viral load test usually is used by clinicians to determine whether antiretroviral medications are working to suppress viral replication in HIV-infected persons taking medication. In fact, the viral load test is NOT an FDA-approved method of testing for the presence of HIV infection. Unlike the previously mentioned HIV tests, these types of tests detect the genetic material (RNA) of the virus rather than antibodies to HIV. Therefore, viral load tests can reveal HIV infection during the weeks before antibodies are produced. When are HIV viral load tests used to detect new infections? They are used to determine whether a baby born to an HIV-infected mother is infected because ELISA tests cannot always make such a determination. Viral load tests also are used when there is a substantial risk for HIV infection from high-risk encounters such as unprotected anal or vaginal sex. HIV viral load tests are not widely available for this purpose, largely because of the cost involved, but also because they can be difficult to interpret. If you are worried that a particular recent sexual episode put you at risk for HIV, you cannot simply go to an HIV testing site and ask for a viral load test. If you are worried, you should go to your doctor, public health clinic, or, in some cases, an HIV testing site and talk to a clinician. He or she can determine your risk for acquiring HIV based on the incident. If the test is available and, in the clinician's opinion, appropriate, a viral load test can be performed. Note that these tests are done on a blood sample drawn from a vein and results can take a few days or even a week or two. You may wonder why viral load tests are not the standard if they can detect HIV much earlier than antibody tests. First, viral load tests are extremely expensive and require highly trained professionals to interpret the results. Second, the viral load test is so sensitive that a false-positive test is a very real concern. Furthermore, in most cases, antibody tests are sufficient to test for HIV because HIV has been present long enough to be detected. Certainly, we have learned in recent months that a small (but significant) number of people who go for HIV testing do in fact have HIV, but have not yet produced antibodies (which, again, can take up to 3 months to appear), so they assume that they are HIV negative. Researchers are demonstrating ways in which ELISA and HIV viral load tests can be combined in a cost-efficient manner so that such cases are not missed.
Detecting Early HIV Infection Using a Combined ELISA and HIV Viral Load
You may have heard of "pooled PCR." Researchers in North Carolina have demonstrated a cost-effective and efficient way to combine standard ELISA tests with viral load tests. Instead of performing viral load tests on individual blood samples, they have found a way to combine or "pool" samples and test multiple people's specimens at one time. If a pooled sample tests positive, the laboratory technicians test individual samples in the pool until they find the sample that is positive. This method allows the benefit of both standard antibody tests and viral load tests to more accurately determine whether someone is HIV infected. If the method catches on across the country, more infections might be identified in the earliest stage, when there is a high likelihood of infecting other people because (a) the viral load is very high, which increases the likelihood of transmitting the virus; and (b) people otherwise may not know they are infected, and may be less likely to practice safer sex. Identifying early infections has the benefit of letting people know sooner and more accurately whether they have HIV infection and has in the indirect benefit of preventing new infections because people who are aware of their HIV status usually take precautions to avoid infecting their partners. Pooled PCR is not widely available.
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