West Nile virus

Symptoms

What are the symptoms of West Nile virus?

Most people (70%-80%) who are infected with West Nile virus have no symptoms at all. Some people have mild symptoms that include:

• fever
• headache
• mild rash
• body aches (might include swollen lymph glands in the neck)

First symptoms usually appear within 2 and 15 days after infection.

Very few people (fewer than 10% of those with symptoms) have more serious symptoms. In many of these cases, the infection affects the central nervous system (nerve tissues in the brain and spinal cord). In addition to the symptoms above, these may include:

• stiff neck
• nausea and or vomiting
• difficulty swallowing
• drowsiness
• confusion
• loss of consciousness
• muscle weakness
• reduced muscle coordination (trouble walking)
• blurred vision or worsening eyesight
• numbness

Recovery can take a week for mild cases and up to a year for more serious cases. Some cases of severe disease can be fatal.

What to do if you become ill

See your health care provider if you develop symptoms of West Nile virus infection.