Besides performing 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:

  • Lab 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. A blood test may not show antibodies at first; another test may need to be done a few weeks later to show the rising level of antibodies.
  • Spinal tap (lumbar puncture). 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 remove a sample of fluid for analysis in a lab. The fluid sample may show an elevated white blood cell count — a signal that your immune system is fighting an infection — and antibodies to the West Nile virus. If the sample doesn't show antibodies, another test may be done a few weeks later.
  • Brain tests. In some cases, doctors may order electroencephalography (EEG) — a procedure that measures your brain's activity — or an MRI scan to help detect brain inflammation.


Most people recover from West Nile virus without treatment. Most people who are severely ill need supportive therapy in a hospital with intravenous fluids and pain medication.

For mild cases, over-the-counter pain relievers can help ease mild headaches and muscle aches. Use caution when giving aspirin to children or teenagers. Children and teenagers recovering from chickenpox or flu-like symptoms should never take aspirin. This is because aspirin has been linked to Reye's syndrome, a rare but potentially life-threatening condition, in such children.

Interferon therapy

Scientists are investigating interferon therapy — a type of immune cell therapy — as a treatment for encephalitis caused by West Nile virus. Some research shows that people who receive interferon recover better than those who don't receive the drug, but further study is needed.

Preparing for your appointment

If you have signs and symptoms of infection of the brain or spinal cord — high fever, severe headache, stiff neck, confusion or sudden muscle weakness — see your doctor right away or go to an urgent care center.

Here's some information to help you get ready for your appointment.

What you can do

Take with you a list of the following:

  • Your symptoms, including any that seem unrelated to why you're seeing a doctor
  • Key personal information, including recent activities or travel to an area where West Nile virus is prevalent
  • All medications, vitamins or other supplements you take, including the doses
  • Questions to ask the doctor

Take a family member or friend along, if possible, to help you remember the information you're given.

For West Nile virus, some basic questions to ask your doctor include:

  • What's likely causing my symptoms?
  • What are other possible causes for my symptoms?
  • What tests do I need?
  • Is my condition likely temporary or chronic?
  • What's the best course of action?
  • What are the alternatives to the primary approach you're suggesting?
  • I have other health conditions. How can I best manage them together?
  • Are there restrictions I need to follow?
  • Should I see a specialist?
  • Are there brochures or other printed material I can have? What websites do you recommend?

Don't hesitate to ask other questions.

What to expect from your doctor

Your doctor is likely to ask you several questions, such as:

  • When did your symptoms begin?
  • Have your symptoms been continuous or occasional?
  • How severe are your symptoms?
  • What, if anything, seems to improve your symptoms?
  • What, if anything, appears to worsen your symptoms?
Dec. 19, 2020
  1. West Nile virus. Centers for Disease Control and Prevention. https://www.cdc.gov/westnile/index.html. Accessed Nov. 30, 2020.
  2. Petersen LR. Epidemiology and pathogenesis of West Nile virus infection. https://www.uptodate.com/contents/search. Accessed Nov. 30, 2020.
  3. Petersen LR. Clinical manifestations and diagnosis of West Nile virus infection. https://www.uptodate.com/contents/search. Accessed Nov. 30, 2020.
  4. AskMayoExpert. West Nile virus infection. Mayo Clinic; 2019.
  5. Petersen LR. Treatment and prevention of West Nile virus infection. https://www.uptodate.com/contents/search. Accessed Nov. 30, 2020.
  6. Tosh PK (expert opinion). Mayo Clinic. Dec. 1, 2020.