West Nile Virus Home > West Nile Virus Symptoms

Not everyone with West Nile virus will develop symptoms. However, when signs and symptoms do occur, they may include things such as fever, body aches, and swollen lymph glands. A very small number of people develop severe West Nile virus symptoms, including neck stiffness, high fever, coma, and paralysis.

Signs and Symptoms of West Nile Virus: An Overview

When a person becomes infected with the West Nile virus, symptoms can vary. Some people will have no symptoms, others may develop flu-like symptoms, and some develop serious symptoms.
No Symptoms
Approximately 80 percent of people who are infected with West Nile virus will not show any symptoms at all.
Mild Symptoms
Up to 20 percent of the people who become infected with West Nile virus have mild symptoms that can include:
  • Fever
  • Headache
  • Body aches
  • Nausea
  • Vomiting
  • Swollen lymph glands
  • Skin rash on the chest, stomach, and/or back.
These symptoms can last from a few days to several weeks. These mild symptoms are sometimes called West Nile fever.
Serious Symptoms
About 1 in 150 people infected with West Nile virus will develop severe symptoms. Symptoms of severe disease (also called neuroinvasive disease, such as West Nile encephalitis, meningitis, or West Nile poliomyelitis) can include:
  • High fever
  • Headache
  • Neck stiffness
  • Stupor
  • Disorientation
  • Coma
  • Tremors
  • Convulsions
  • Muscle weakness
  • Vision loss
  • Numbness
  • Paralysis.
These severe West Nile virus symptoms may last for several weeks, but neurological effects may be permanent. Neurological effects can include:
  • Hearing and/or speech loss
  • Blindness
  • Permanent brain and/or nerve damage
  • Behavioral changes
  • Cognitive disabilities
  • Lack of muscle control
  • Seizures
  • Memory loss.
Written by/reviewed by:
Last reviewed by: Arthur Schoenstadt, MD
Last updated/reviewed:
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