Types of HIV Tests

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HIV testing occurs in a variety of settings outside the laboratory in Botswana, such as all government health facilities (hospitals and clinics), private clinics, and Non- governmental organizations including Tebelopele, BOCAIP and BOFWA. Currently different antibody tests are available. These include Enzyme Linked Immunosorbent Assays (ELISA) and Rapid HIV Tests that play an important role in diagnosing those who are infected with the HIV virus.

HIV tests performed in Botswana

HIV Rapid Tests

In Botswana, Routine HIV Testing is considered to be diagnostic test for HIV. It provides excellent tool for expansion of HIV testing services. Most HIV rapid tests can detect both HIV 1 and HIV 2, with some kits having the ability to distinguish the two. In Botswana a parallel testing atrategy is followed in which two tests, namely unigold and determine are performed simultaneously and the HIV status is determined when both tests produce the same results. When both give negative result, it is diagnosed as concordant negative and when both are positive it is diagnosed as concordant negative. Such results are given as negative and positive status respectively. However if one of the two rapid tests is positive and the other one negative, the HIV status becomes indeterminate and therefore the test result is not given to the patient. In case of discordancy, the tests are repeated and if the result persists to be indeterminate, the patient is referred for ELISA test that is done only in the Laboratory.

The rapid tests are reliable and accurate. Moreover, the test needs minimal equipment and the tester needs minimum technical skill. Rapid tests must be appropriately evaluated prior to use and only trained and certified personnel should do the test.

Advantages of Rapid Tests

  • Same day diagnosis as the tests can be done under 30 minutes.
  • Whole blood can be used for testing
  • Only a few drops of blood are necessary for the test

ELISA test

ELISA tests use similar principle as in HIV rapid tests in that they are based on antibody-antigen reaction. This method is however complex and needs to be performed by a properly trained laboratory technician. ELISA tests are usually recommended for high volume testing sites. Some ELISA tests target antibodies in the patient specimen while others detect both HIV antibodies and antigens in an attempt to reduce the window period.

DNA/RNA PCR (Polymerase Chain Reaction)

In this test, HIV nucleic material is multiplied/amplified and consequently detected in the patient specimen. Since the test targets the virus itself or part of it, PCR is the test of choice used to diagnose children under the age of 18 months in Botswana Antibody tests do not provide accurate results in children under 18 months due to the fact that maternal antibodies of HIV positive mothers are found in their blood. DNA PCR is done in children of 6 weeks to 18 months of age.

Western Blot (WB)

Western Blot detects antibodies to specific antigens on cellulose strips. It is a supplemental test for confirming HIV results . Western Blot is also used in Kit evaluation to confirm the status of specific samples. Issues concerning Western Blot are that it is expensive, sophisticated and has limited availability.