How should the results be interpreted when ELISA is positive, repeat ELISA is negative, and Western blot shows no bands?

When interpreting test results in the context of HIV testing, a positive ELISA followed by a negative repeat ELISA and a Western blot showing no bands points towards a negative result for HIV.

The initial positive ELISA indicates the presence of antibodies that may suggest HIV infection. However, the subsequent negative repeat ELISA generally calls the initial result into question, indicating that the antibodies detected in the first test may not be specific to HIV or might be present due to other factors, such as cross-reactivity or transient non-specific antibodies.

Furthermore, the Western blot, which is a more specific test usually used to confirm HIV infection if the ELISA results are positive, showing no bands further supports the interpretation of a negative HIV status. Western blot testing detects specific antibodies to HIV proteins; therefore, the absence of bands confirms that there are no specific antibodies relevant to HIV present in the sample.

Given the context of these results—the positive ELISA, the negative repeat, and the absence of bands on the Western blot—the overall interpretation is most accurately described as negative for HIV. This negative result is crucial for clinical decision-making and patient management, indicating no HIV infection is present despite the initial reactive screening test.