My HIV screening was reactive but the confirmatory test showed no HIV antibodies; given no risk exposures for eight years, a normal CD4 count, and a history of Lyme disease, what does this result indicate and what should be done next?

Your HIV Test Result is a False Positive

You do not have HIV infection. A reactive screening test followed by a negative confirmatory antibody test, combined with no risk exposures for eight years and a normal CD4 count, indicates a false-positive result 1.

Understanding Your Test Results

Your screening test (likely a 4th generation HIV antigen/antibody combination assay) was "reactive," but the confirmatory test showed "no HIV antibody detected." According to current CDC and IDSA guidelines, this pattern has two possible interpretations:

• Acute HIV infection (very early infection where p24 antigen is present but antibodies haven't developed yet)
• False-positive screening test (no actual HIV infection)

In your case, the false-positive interpretation is definitive because:

• You have no risk exposures for 8 years (HIV would have been detected long ago if present)
• Your CD4 count is normal (would be significantly depleted with untreated HIV over 8 years)
• The confirmatory antibody test is negative

Why This Happened

False-positive HIV screening tests occur due to cross-reactive antibodies. Lyme disease is a known cause of false-positive HIV tests 2. The spirochete Borrelia burgdorferi (which causes Lyme disease) shares immunogenic proteins that can trigger antibodies that cross-react with HIV test antigens, particularly in ELISA/immunoassay screening tests 2, 3.

Other conditions that cause false positives include:

• Autoimmune disorders
• Recent viral infections (EBV, CMV)
• Pregnancy
• Hematologic malignancies with hypergammaglobulinemia 4, 3

What You Need Next

HIV RNA (viral load) testing should be performed to definitively rule out acute HIV infection 1. This is the final step in the modern CDC algorithm when screening is reactive but confirmatory antibody testing is negative.

The testing sequence should be:

1. ✓ Reactive screening test (completed)
2. ✓ Negative HIV-1/HIV-2 antibody differentiation assay (completed)
3. → HIV-1 RNA qualitative or quantitative test (needed now)

If the HIV RNA test is undetectable/negative, you definitively do not have HIV infection 1, 5.

Important Caveats

• Do not accept an HIV-positive diagnosis based solely on a reactive screening test 6, 7
• The combination of your clinical history (no exposures for 8 years, normal CD4 count) makes acute HIV infection biologically implausible
• Your Lyme disease history provides a clear explanation for the false-positive screening result 2
• False-positive results are particularly common in populations with cross-reactive antibodies from other infections 3

Request the HIV RNA test from your provider to complete the diagnostic algorithm and obtain definitive documentation that you are HIV-negative 1.