Wadsworth Center

TABLE A-2

INTERPRETATION OF SYPHILIS TEST RESULTS USING RPR/VDRL SCREENING

RPR/VDRL SCREENING TEST RESULT FTA-ABS (MHA-TP) RESULT INTERPRETATION
Non-reactive

Repeatedly reactive


Repeatedly reactive

 N/A

Non-reactive


Reactive

Negative

Negative. False positive screen.

Positive syphilis serology.
Suggests current infection.

HIV-1/HIV-2 CONFIRMATION

Confirmation of HIV-1/HIV-2 screening test results is usually accomplished using an algorithm recommended by the FDA (Figure l). The intent of this algorithm is to apply additional, more specific tests for detection of antibodies to HIV-1 and/or HIV-2 in donor serum or plasma. In some cases, it may not be possible to differentiate HIV-1 from HIV-2 using this algorithm because of extensive antibody cross-reactivity.

HIV-1 WESTERN BLOT

In the first step, donor samples repeatedly reactive in the HIV-1/HIV-2 combined EIA are tested by an FDA-approved HIV-1 Western blot kit. Interpretation conforms to the recommendations contained in the manufacturer's package insert, with some modifications based on recommendations by the Centers for Disease Control and Prevention (CDC) and the published literature. Test results for the HIV-1 Western blot are:

    NEGATIVE- The sample does not contain detectable antibodies to HIV-1, but may contain antibodies to HIV-2.

    INDETERMINATE- No conclusive determination about the presence of antibodies to HIV-1 or HIV-2 antigens may be made on this sample. Additional testing for HIV-2 is recommended. The observed pattern may have no significance in populations at low risk of exposure. However, patterns in this category have been observed during seroconversion of individuals at risk. Additional confirmatory testing of a new blood sample is recommended. A persistent indeterminate pattern for a period of at least six months indicates that the individual is not infected with HIV.

    POSITIVE - The sample contains specific antibodies to HIV-1.

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