|  | Public Health Safety | Public Health

What Causes False Positive HIV?

While the chances of receiving one are quite low, false positive HIV tests are distributed to patients from time to time. Here are several reasons this could occur.

  1. The Test

    • Medical laboratories perform enzyme-linked immunosorbent assays, or ELISAs, to determine whether a blood sample is HIV positive. A Western Blot can be done next to confirm the ELISA results. An average of 0.2 percent of ELISAs give out a false positive.

    Disease

    • If the patient already has a liver disease or autoimmune disease, the test could come back positive. The latter is due to HIV itself being a virus that attacks the autoimmune system.

    Pregnancy

    • If a woman is being tested during or directly following a second pregnancy, she could test positive to HIV falsely. This can occur because pregnancy affects the immune system.

    Vaccination and Hospitalization

    • If you have had a rabies or Hepatitis B vaccination, or an influenza shot, a false positive might show up when testing for HIV. The same is true for blood transfusions and hemiodialysis. Contamination in the laboratory is also a possibility.

    Drugs

    • If your parents were substance abusers when you were born, or if you have a history of injection drug use, a false positive may arise on an HIV test.

    Reasoning

    • Each of the above causes for false positive HIV test readings stimulate the body's immune system, leading to the production of antibodies. Said antibodies could react with antigens from the virus, resulting in the wrong result.

Public Health - Related Articles