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WNV Healthcare Provider Information

Commercial laboratory tests for West Nile virus by serology (IgM capture ELISA) or polymerase chain reaction are now available. Any patient testing positive for West Nile virus at a commercial laboratory should be reported to the local health department. For reporting purposes, confirmatory testing at the Illinois Department of Public Health (IDPH) or the U.S. Centers for Disease Control and Prevention is typically required by IDPH for validation of commercial laboratory tests that are positive for West Nile virus.

Testing Guidelines

  • Diagnostic testing for WNV is generally NOT recommended for individuals with non-specific "flu-like" symptoms in the outpatient setting. There are many causes of these non-specific symptoms and testing for WNV would be non-productive for the majority of patients.
  • WNV testing should also be considered in the setting of other neurologic syndromes, especially severe muscle weakness. Approximately 10 percent of patients in the 1999 New York outbreak had complete flaccid paralysis and were originally suspected to have Guillain-Barre syndrome.