HHV-6 Ab (Human Herpesvirus 6)
Immunity & allergy markersWhat the test generally measures, and what to ask about it.
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What is HHV-6 Ab (Human Herpesvirus 6)?
Measures antibodies against human herpesvirus 6 (HHV-6), a common virus best known for causing roseola in young children.
This test measures IgG and/or IgM antibodies against human herpesvirus 6 (HHV-6), a widespread virus that most people are exposed to in early childhood, often causing roseola, a mild illness with fever and rash. It relates broadly to the immune system, and like other herpesviruses, HHV-6 can remain dormant in the body long-term after initial infection. Clinicians commonly order it when evaluating unexplained fever or rash in young children, or in adults with a weakened immune system when reactivation is a concern. A positive IgM generally suggests more recent infection or reactivation, while a positive IgG generally reflects past exposure, which is extremely common in the general population.
Tests often checked alongside this
- Complete Blood Count (CBC) — general marker of immune and inflammatory activity
- EBV VCA IgG/IgM and CMV Ab — other herpesviruses sometimes considered together when evaluating similar symptoms
How this can show up in how you look and feel
- May be associated with fever and a subsequent rash in young children, consistent with roseola
- May be associated with fatigue during active or reactivated infection
- May be associated with more significant symptoms in people with a weakened immune system
What can affect this marker
- Age, since most people are exposed to HHV-6 in early childhood
- Immune status, particularly relevant for reactivation
- Timing of exposure relative to testing
- Lab-to-lab variability in assay methods
What to track over time
- Whether IgM or IgG antibodies are present, or both
- How results relate to symptom timing, especially in young children
- Whether repeat testing is useful in the context of a weakened immune system or reactivation concerns
What to ask your doctor
- Does this result suggest recent, past, or reactivated HHV-6 infection?
- How does this relate to my or my child's current symptoms?
- Is any additional monitoring needed given my immune status?
- Could symptoms be explained by another common childhood illness?
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References
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Official sources
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