Most people infected with West Nile virus do not have symptoms. Others have mild symptoms. In rare cases, infection can lead to inflammation of the brain (encephalitis), the spinal cord (myelitis), or the tissues surrounding it and the spinal cord (meningitis). The time from infection to the appearance of symptoms (incubation period) usually is 3 to 14 days. Symptoms of the mild form of West Nile virus include:

• Fever.
• Headache, body aches, or pain in your eyes.
• Skin rash.
• Feeling tired.
• Not feeling hungry.
• Feeling sick to your stomach or throwing up.
• Swollen glands (lymph nodes) (possibly).

Most people who have the mild form of West Nile virus have a fever for 5 days, a headache for 10 days, and feel tired for more than a month.⁴

More severe infections involving the brain and spinal cord may cause:

• Headache.
• High fever.
• Stiff neck.
• Disorientation.
• Reduced attention to surroundings.
• Tremors and convulsions.
• Muscle weakness or paralysis.
• Coma.

If you or a person in your care has symptoms like these, contact your doctor immediately.

You may have tremors, muscle aches, and fatigue for months after the illness, especially if your brain became infected. Other possible effects include seizures, memory loss, personality changes, paralysis, and symptoms similar to Parkinson's disease. Some of these problems may last a long time.