West Nile Virus in Children
What is the West Nile virus?
The West Nile virus belongs to a group of viruses known as flaviviruses, commonly
found in Africa, West Asia, Australia, Europe, and the Middle East. Flaviviruses are
spread by insects, most often mosquitoes. Other examples of flaviviruses include yellow
fever, Japanese encephalitis, dengue virus, and St. Louis encephalitis virus. West
Nile virus (WNV) is closely related to the St. Louis encephalitis virus.
The West Nile virus can infect humans, birds, mosquitoes, horses, and some other mammals.
In 1999, the virus occurred in the Western hemisphere for the first time, with the
first cases reported in New York City. Since then, West Nile virus has been considered
an emerging infectious disease in the U.S., as it has spread down the East Coast and
to many Southern and Midwestern states. It has been discovered in 48 states in the
West Nile virus occurs in late summer and early fall in temperate zones, but can occur
year-round in southern climates. Most people are infected from June to September. Usually,
the West Nile virus causes mild, flu-like symptoms. Rarely, the virus can cause life-threatening
illnesses, such as encephalitis (inflammation of the brain), meningitis (inflammation
of the lining of the brain and spinal cord), or meningoencephalitis (inflammation
of the brain and its surrounding membrane).
What are the symptoms of West Nile virus?
According to the CDC, West Nile virus infection in humans is rare. Most children infected
with West Nile virus have only mild, flu-like symptoms that last a few days. Symptoms
usually appear within 3 to 14 days of infection.
Approximately 20% of the people who become infected will develop West Nile fever.
The following are the most common symptoms of West Nile fever:
The more severe form of the West Nile virus (West Nile encephalitis, West Nile meningitis,
or West Nile meningoencephalitis) that is present in one out of 150 cases, occurs
when the virus crosses the blood-brain barrier. Most of these cases are in people
over 60. Symptoms of West Nile encephalitis, West Nile meningitis, or West Nile meningoencephalitis
in children may include:
The symptoms of West Nile virus may look like other conditions or medical problems.
Always see your child's healthcare provider for a diagnosis.
Diagnosis of the severe form of West Nile virus may include tests such as lumbar puncture
(spinal tap), electroencephalogram (EEG), CT scan, magnetic resonance imaging (MRI),
and blood tests.
How is West Nile virus spread?
West Nile virus is transmitted to humans through the bite of an infected female mosquito.
The mosquitoes acquire the virus through biting infected birds. Crows and jays are
the most common birds associated with the virus, but at least 110 other bird species
also have been identified with the virus.
According to the CDC, West Nile virus isn't spread between humans. However, in recent
developments, several cases were documented of organ transplant recipients who contracted
the disease from their donors. Health officials suspect the organ donor acquired the
virus through a blood transfusion. As a result, the government is working to develop
a blood-screening test for West Nile virus. However the FDA stresses that the risk
for contracting West Nile from blood is significantly lower than the risk for forgoing
any procedure that would call for a blood transfusion.
What is the treatment for West Nile virus?
There's no specific treatment for West Nile virus-related diseases. If a person develops
the more severe form of the disease, West Nile encephalitis or meningitis, treatment
may include intensive supportive therapy, such as:
How is West Nile virus prevented?
Currently, there's no vaccine available to prevent West Nile virus. The CDC recommends
taking the following steps to avoid mosquito bites:
Apply insect repellent containing DEET (N,N-diethyl-meta-toluamide) to exposed skin
when your child is outdoors.
When possible, have your child wear long-sleeved shirts and long pants treated with
repellents containing permethrin or DEET since mosquitoes may bite through thin clothing.
(Don't directly apply repellents containing permethrin to exposed skin.)
If you spray your child's clothing, there is no need to spray repellent containing
DEET on the skin under the clothing--however, do apply DEET containing repellent to
Consider keeping your child indoors at dawn, dusk, and in the early evening, as these
are peak hours for mosquito bites, especially those mosquitoes that carry the West
Eliminate standing water sources around your home to limit the number of places available
for mosquitoes to lay their eggs.
What should I know about insect repellents?
Mosquitoes are attracted to people’s skin odors and the carbon dioxide from a person’s
breath. Many repellents contain a chemical, N,N-diethyl-meta-toluamide (DEET), which
repels the mosquito. Repellents are effective only at short distances from the treated
surface, so mosquitoes may still be flying nearby. Always follow the directions on
the insect repellent you're using to determine how frequently you need to reapply
Sweating, perspiration, or water may require reapplication of the product.
Use enough repellent to cover exposed skin or clothing. Don't apply repellent to skin
that's under clothing. You don't need a heavy application to get protection.
Do not apply repellent to cuts, wounds, or irritated skin.
After your child returns indoors, wash treated skin with soap and water.
Do not spray aerosol or pump products in enclosed areas.
Do not apply aerosol or pump products directly to your child's face. Spray your hands
and then rub them carefully over the face, avoiding the eyes and mouth.
According to the CDC, repellents containing a higher concentration of active ingredient
(such as DEET) provide longer-lasting protection.
A product containing 23.8% DEET provides an average of 5 hours of protection from
A product containing 20% DEET provides almost 4 hours of protection from mosquito
A product with 6.65% DEET provides almost 2 hours of protection from mosquito bites.
Products with 4.75% DEET and products made from citronella, eucalyptus, or soybean
oil are able to provide roughly 1.5 hours of protection from mosquito bites.
Are there special concerns about the use of insect repellents on children?
The American Academy of Pediatrics recommends using caution when applying insect repellent
Use products with DEET concentrations of 30% or less on children ages 2 to 12. (Some
experts suggest that it is acceptable to apply repellent with low concentrations of
DEET to infants older than 2 months.) There is no evidence that using DEET concentrations
greater than 30% offer any additional benefit.
When using repellent on a child, apply it to your own hands and then rub them on your
Avoid children's eyes and mouth and use the repellent sparingly around their ears.
Do not apply repellent to children's hands because children tend to put their hands
in their mouths.
Do not allow a young child to apply his or her own insect repellent.
Keep repellents out of reach of children.
Do not use combination sunscreen-insect repellent products because reapplying frequently
enough to prevent sunburn will expose your child to too much DEET.
Do not apply repellent to skin under clothing. If repellent is applied to clothing,
wash treated clothing before wearing again.
Do not apply permethrin containing repellants directly to your child's skin.
Always consult your child’s healthcare provider for more information.