By John A.D. Leake, M.D.

What is West Nile Virus?

West Nile Virus is an infection transmitted by mosquitoes, nearly always in summer or early autumn. Most infected people have no symptoms at all, or have only mild symptoms resembling influenza (“the flu”). Less than 1% of people infected with West Nile have a serious illness of the central nervous system (brain and spinal cord), but this only rarely occurs in children.

How many kids are affected by this virus?

During the past five years in the United States, approximately 250 cases (none fatal) of West Nile Virus have been reported in kids and adolescents.

What are the symptoms?

West Nile Virus most often causes “West Nile Fever” with the following symptoms:

• fever 
• headache
• muscle aches
• rash
• vomiting or diarrhea
• decreased appetite

More rarely (and usually among older adults), West Nile Virus may cause meningoencephalitis (inflammation of the brain or spinal cord) with the following:

• decreased alertness (lethargy)
• extreme weakness
• stiff neck
• seizures
• inability to move an arm or leg

When should a parent worry about their child with this type of illness?

It is most important to watch for signs of brain or spinal cord swelling (listed above), plus other routine signs you would watch for in a child like high fever or dehydration.

What can parents do if they suspect their child has West Nile Virus?

Call your primary care doctor if you are worried about your child having symptoms that could be due to West Nile Virus, especially if they have been bitten by a mosquito within the past two weeks.

Is there any medication that can be given for West Nile Virus?

There are no currently approved medications for West Nile Virus. The treatment is supportive (rest, fluids, medication to decrease fever), and this may usually be done at home. Seriously ill patients may need to be hospitalized.

Can West Nile Virus be prevented?

West Nile Virus is best prevented by avoiding mosquito bites, especially during the hours from dusk until dawn. Use DEET-containing insect repellents; these are effective and safe for persons of all ages (up to concentrations of 30%--apply as directed), and wear long pants and long-sleeved shirts when outside in the evening. It is also a good idea to minimize the potential for mosquito bites and breeding near your home:  make sure screens are intact on doors and windows, drain puddles of water in plants and containers, keep pools clean, remove any discarded items such as old tires, and so on.

A vaccine against West Nile Virus is already available for horses, which may be severely affected by the illness. Researchers are working on a new human vaccine, and on specific treatments that will be effective against the virus.

CSSD Division of Infectious Disease

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