West Nile Virus Antibody

The West Nile Virus IgG/IgM test detects antibodies produced by the immune system in response to infection with West Nile virus, a mosquito-borne virus that can affect the nervous system. This blood test measures both IgM antibodies, which may indicate recent infection, and IgG antibodies, which suggest past exposure or immune response.

West Nile virus infection may cause symptoms ranging from mild fever and fatigue to more serious neurological illness in some individuals. Antibody testing helps determine whether a person has been recently infected or exposed in the past.

West Nile virus antibody testing helps assess:

• Possible recent West Nile virus infection
• Past exposure to West Nile virus
• Evaluation of unexplained fever or viral illness
• Investigation of neurological symptoms following mosquito exposure
• Immune response following suspected infection

Reference Range

Results are typically reported as Negative, Borderline, or Positive for both IgM and IgG antibodies.

What Your Results May Mean

• Positive IgM: May indicate recent or active infection with West Nile virus.
• Positive IgG: Suggests past exposure or previous infection.
• Negative: No detectable antibodies at the time of testing.

Results should be interpreted alongside clinical symptoms and exposure history. In early infection, antibodies may not yet be detectable, and follow-up testing may sometimes be recommended.