West Nile virus causes an infection that can lead to inflammation of the brain (encephalitis), the spinal cord (myelitis), or the tissues surrounding it and the spinal cord (meningitis). No specific treatment is available. Mild infections go away on their own. Severe cases of encephalitis are treated with supportive care in a hospital. Supportive care involves helping the body fight illness on its own. It often is used when no specific treatment exists for an illness, as is the case with some viruses.

Supportive treatment for West Nile virus can include receiving fluids through a vein (intravenous, or IV), help with breathing (using a ventilator), and prevention of secondary infections, such as pneumonia. For more information, see the topic Encephalitis.