Diagnosis

Besides conducting a physical exam, your doctor can confirm the presence of West Nile virus or a West Nile-related illness, such as meningitis or encephalitis, by performing one of the following tests:

  • Laboratory tests. If you're infected, a blood test may show a rising level of antibodies to the West Nile virus. Antibodies are immune system proteins that attack foreign substances, such as viruses.
  • Lumbar puncture (spinal tap). The most common way to diagnose meningitis is to analyze the cerebrospinal fluid surrounding your brain and spinal cord. A needle inserted between the lower vertebrae of your spine is used to extract a sample of fluid for laboratory analysis. The fluid sample may show an elevated white cell count — a signal that your immune system is fighting an infection — and antibodies to the West Nile virus.
  • Brain tests. In some cases, an electroencephalography (EEG) — a procedure that measures your brain's activity — or an MRI scan can help detect brain inflammation.
Dec. 16, 2015
References
  1. West Nile virus. Centers for Disease Control and Prevention. http://www.cdc.gov/westnile/index.html. Accessed Oct. 4, 2015.
  2. Petersen LR. Clinical manifestations and diagnosis of West Nile virus infection. http://www.uptodate.com/home. Accessed Oct. 4, 2015.
  3. Petersen LR. Treatment and prevention of West Nile virus infection. Accessed Oct. 4, 2015.