Understand Your HIV Testing Options

Experts agree that HIV testing is an essential part of stopping the spread of HIV. In fact the Centers for Disease Control (CDC) is now recommending that HIV testing be part of every routine medical exam and physical. To that end, people seeking HIV testing have a choice as to which type of HIV testing to use; conventional HIV testing or rapid HIV testing. There are two primary types of HIV testing:

• The ELISA / Western Blot - The standard screening test for HIV is a blood test known as the enzyme immunoassay (EIA) or ELISA for short. This HIV testing requires a small sample of blood from the person being tested. Typically, the test requires two visits; one to receive pretest counseling and have your blood drawn and the second to receive HIV testing results, post-test counseling and medical referrals for HIV care if the results are positive.

• Rapid HIV Testing - This type of HIV testing makes it possible for the patient to get pre-test and post-test counseling, their test results, and any medical referrals they may need all in one visit and in a very short amount of time. Let's learn more about rapid HIV testing.

  CDC Testing Guidelines

  Understanding HIV Testing

What is Rapid HIV Testing?

Rapid HIV testing differs from conventional HIV testing in that it allows:

• results of the test to be ready in 5 to 30 minutes
• HIV testing, counseling, and referrals can be done in one visit

Currently there are four rapid HIV tests approved for use by the Food and Drug Administration(FDA).

• OraQuick / OraQuick Advanced Rapid HIV-1/2 Antibody Test - this type of HIV testing has been approved for use with venous blood, plasma, and oral fluids for the detection of HIV-1 and HIV-2. The test consists of a small test paddle. The test area on the paddle is impregnated with HIV-1 and HIV-2 proteins. The test specimen (blood, plasma, or oral fluid) is applied to the paddle (in the case of oral fluid the paddle is swabbed in the inside of the mouth) and placed in developer solution. If the specimen contains HIV, it binds with the impregnated proteins on the HIV testing paddle causing in a red line to appear. Red lines appearing in the test area and control area of the paddle indicates a positive test. All positive tests require a confirmatory blood test. The rapid test should be read no sooner than 20 minutes and no later than 40 minutes after the sample is placed in the developing solution.

• Reveal G2 HIV-1 Antibody Test - this type of rapid HIV testing has been approved for use with plasma or serum specimens. While the test only takes 3 minutes to develop, the test is more complex than the OraQuick because it requires centrifuged serum or plasma. The test consists of a cartridge with a test area. Like the OraQuick, any HIV present in the test specimen binds with the protein impregnated in the test area, causing a red dot to appear. If a red dot appears along with a red line used as a control the test is considered positive, requiring a confirmatory test.

• Uni-Gold Recombigen HIV-1 Test - this hiv testing has been approved for us with whole blood, plasma, or serum from a venipuncture or finger stick. It consists of a rectangular cartridge with a test area, a control area, and a specimen well. The specimen is applied into the specimen well and allowed to absorb, tracking along the test strip past the control and test areas. As is true in the first two tests we've discussed, any HIV in the specimen binds to the proteins in the test area, causing a red line to appear. A test is considered positive if a red line appears in both the test area and the control area. A sample is considered adequate if the specimen well is red in color. Like all rapid tests if the test is positive a confirmatory test is required.

• Multispot HIV-1/HIV-2 Rapid Test - this hiv testing has been approved for use on frozen and fresh plasma, whole blood, or serum. Multispot consists of a test cartridge and five reagents:
  • a specimen diluent
  • a wash solution
  • a conjugate
  • a development reagent
  • and a stop solution.
  The cartridge contains a membrane on which microparticles have been immobilized in four spots; two HIV-1 test spots; one HIV-2 test spot; and one control spot to verify that the specimen is adequate. The test is considered positive for HIV-1 if the control spot and either or both of the HIV-1 spots turn purple, and positive for HIV-2 if the control and HIV-2 spots appear. If purple appears in the control spot, the HIV-2 spot, and one or both of the HIV-1 spots, the test is considered HIV reactive (undifferentiated). In this case, the specimen may be tested by additional methods which allow differentiation between HIV-1 and HIV-2. The test is negative when only the control spot appears. The absence of the control spot indicates an invalid result, regardless of any other spot pattern.

False Positive Tests Do Occur

One problem with rapid HIV testing is the occurrence of false positive tests. In fact there have been reports of higher than expected false positive results in some parts of the country. While the cause of these results are not known yet, experts urge that all positive rapid tests be confirmed with a conventional ELISA and Western Blot.

What's Are the Advantages of A Rapid HIV Testing?

There are distinct advantages of rapid testing over conventional testing. They include:

• they are less costly for HIV testing agencies whose budgets are limited
• almost all people tested will get post-test counseling and their results because only one visit is necessary
• because results are delivered quicker, positive people get into medical care quicker
• by learning of infections earlier, potential exposures that would have occurred between traditional testing and receiving results is reduced
• rapid tests are easier to use
• their results that are as accurate as a traditional Elisa test

Is a Confirmatory Test Required if the Rapid Test is Positive?

As is true of conventional ELISA HIV testing, a positive rapid HIV test result should be confirmed with the Western Blot test.

What is A Western Blot Test?