Final answer:
The EIA/ELISA test is considered a screening procedure for HIV detection. It is used to detect anti-HIV antibodies. Confirmatory tests such as Western blot or PCR follow a positive ELISA result.
Step-by-step explanation:
The procedure considered to be a screening procedure for the detection of HIV is the Enzyme Immunoassay (EIA), commonly referred to as ELISA (enzyme-linked immunoassay). The EIA procedure is widely used as an initial screening test because it is designed to detect antibodies produced in response to HIV infection. If antibodies to HIV are present in the blood, they will bind to the HIV antigens on the well plate and can be detected through a subsequent reaction with an enzyme-linked secondary antibody. In the case of a positive result, which may sometimes be a false positive due to cross-reactivity, confirmatory tests such as the Western blot or Polymerase Chain Reaction (PCR) are then used to confirm an HIV diagnosis.
While Western blot is often used to confirm positive results from the ELISA test, it is not a screening procedure due to its complexity, cost, and higher rate of indeterminate results which neither confirm nor invalidate the results of the ELISA. Furthermore, PCR is a highly sensitive method that detects the genetic material of the virus, which is used for confirming the presence of HIV as well as measuring the viral load, but it is not typically used as an initial screening due to its cost and complexity.