West Nile Virus | Testing & Diagnosis

How is West Nile Virus diagnosed?

To determine a child’s risk of having a West Nile virus infection, the doctor will observe their symptoms and ask about exposure to mosquitos.

A diagnosis of West Nile virus can be confirmed using blood tests. Someone who is infected with West Nile virus will have an increased level of antibodies against the disease. Antibodies are proteins produced by the immune system that attack foreign substances such as viruses, bacteria and other harmful organisms. Elevated levels of antibodies signal that your immune system is fighting the infection by producing a surplus of antibodies.  

If encephalitis is suspected, the following procedures may be used as to confirm the diagnosis:

  • Lumbar puncture (spinal tap): During a spinal tap, a special needle is placed into the lower back and a small amount of cerebral spinal fluid is removed. This fluid sample is sent for testing to determine if a child has West Nile virus or other problems.
  • Electroencephalogram (EEG) An EEG works by recording the brain's continuous electrical activity using stickers attached to the scalp that measure electrical activity. The purpose of an EEG is to see if your child is having small brain seizures that are not visible from the outside.
  • Magnetic resonance imaging (MRI): An MRI takes detailed X-ray images of the brain that can help detect brain inflammation.