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You might not be familiar with the term arbovirus, but thanks to widespread media coverage in recent years, most people now know about the arbovirus called West Nile virus.

Arboviruses are spread to humans by mosquitoes, ticks, and sandflies and can cause infections of the central nervous system, inflammation of joints, or fever with bleeding and liver infection. West Nile virus is now the most common arbovirus in the United States. Although other arboviruses occur in isolated parts of the United States, including the St Louis encephalitis virus, California encephalitis virus, and eastern equine encephalitis virus, West Nile virus has received the most attention. The first outbreak was in 1999 on the East Coast. Every year since then, the virus has moved across the United States and the number of people who become infected has increased.

Mosquitoes contract the virus by feeding on infected birds, or occasionally on other infected animals like horses, bats, and squirrels, and pass it along to humans. If an infected mosquito bites your child, the virus will multiply in her bloodstream, which could eventually cause her to become ill.

Signs and Symptoms

Most children who get West Nile virus have only mild symptoms or no symptoms at all. Symptoms may include

  • Fever
  • Headaches
  • Body aches
  • Nausea
  • Vomiting
  • Skin rash

In a very small number of infected children (fewer than 1% of cases), the illness can become severe and involve the brain (West Nile Virus encephalitis or meningitis). Symptoms involving the brain include high fever, stiff neck, severe headaches, muscle weakness, mental confusion, tremors, vision problems, convulsions, paralysis, and loss of consciousness.

When to Call Your Pediatrician

If your child experiences any of the symptoms that are associated with a severe West Nile virus infection, such as high fever, severe headaches, and a stiff neck, contact your pediatrician.

How Is the Diagnosis Made?

Your doctor will perform a lumbar puncture (spinal tap) to see if meningitis is present. The pediatrician may also order blood tests to help diagnose a West Nile virus infection. An EEG and imaging studies (computer tomography [CT] scan or magnetic resonance imaging [MRI]) are often done to help identify the type of brain infection.


No specific medicine is available to treat West Nile virus infections. Fortunately, mild cases of West Nile virus infection do not require treatment. However, children who become severely ill will require hospitalization and supportive care.

What Is the Prognosis?

In most children with West Nile virus infections, the symptoms disappear in a few days.


To protect your child from a West Nile virus infection, keep her away from places where mosquitoes gather or lay their eggs, such as standing water in bird baths and flower pots. Be sure to remove standing water in your yard and house.

Particularly if you live in a region where West Nile virus has been reported, apply insect repellent to your child’s exposed skin when she’s outdoors. Choose a repellent that contains the chemical DEET. However, products containing DEET should not be applied to infants younger than 2 months and be used only lightly around the eyes and mouth in all children. Because mosquitoes are most likely to bite at dawn and in the early evening, consider keeping your child indoors during these times of day.

West Nile virus can’t be spread from person to person, so there’s no need to keep your child away from someone who has the infection.

No vaccine has been developed to protect your child from West Nile virus.


Last Updated
Immunizations & Infectious Diseases: An Informed Parent's Guide (Copyright © 2006 American Academy of Pediatrics)
The information contained on this Web site should not be used as a substitute for the medical care and advice of your pediatrician. There may be variations in treatment that your pediatrician may recommend based on individual facts and circumstances.