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Ask Dr. Sears: Worry About West Nile Virus

Q. I'm worried about our toddler getting West Nile Virus, since he plays outside a lot and we live in an area that has lots of mosquitoes. What type of mosquito repellent would you recommend for toddlers?

West Nile Virus (WNV) has been in the news a lot lately. Yet the good news is that given proper precautions, your child is very unlikely to get this viral illness. Here are some facts about this virus: Even though there were nearly ten thousand cases reported throughout the United States last year, about eighty percent of infected persons show no symptoms and don't get sick. About twenty percent of infected persons get flu-like symptoms: headache, fever, body aches, nausea, diarrhea, and abdominal pain. The main reason for the worry about WNV is that in approximately one percent of infected persons the virus can invade the nervous system and lead to encephalitis or meningitis. This severe form of WNV infection occurs much more commonly in adults than children. Even though WNV is starting to occur throughout the country, it is most prevalent in the Midwestern states.

WNV is transmitted through the bite of mosquitoes, so that it occurs most frequently during the times of the year and time of the day when mosquitoes are the most active. Rarely, it may be transmitted through a blood transfusion. While in 99 percent of infected persons the virus needs no treatment or laboratory tests, if a person is worried that they have WNV, it can be diagnosed by a blood test for the presence of the WNV antibody. The incubation period for this virus (the time between contact with the virus and developing symptoms) ranges from two to fourteen days, but usually symptoms occur within six days after the mosquito bite. Even though infection with WNV is unlikely, here are things you can do to protect your family, especially your toddler, from coming in contact with this virus.

Move away from mosquitoes. No, you don't have to move your whole house, just stay away from places that mosquitoes frequent. During mosquito season, stay indoors around the hours of dawn and dusk, the times of the day mosquitoes seem to come out and play -- and eat. During our family camping and vacation trips we purposely try to position ourselves in windy areas, since mosquitoes prefer to hang around in areas where the air is calm. Get rid of pools of stagnant water around your home, such as blocked rain gutters, empty flower pots, buckets, and spare tires. These little pools become breeding grounds for mosquitoes. Drill holes in the bottom of tire swings and garbage recycling containers to let the water drain out, as these areas are also common breeding grounds for mosquitoes. Also, don't let your children play with dead birds, which may be infected with WNV. And, be sure the screens on your windows and doors fit tightly.

Dress for protection. Wear long sleeves, long pants, and socks to prevent the mosquitoes from attacking bare skin.

Repel those mosquitoes. Studies have shown DEET (permethrin) to be the most effective insect repellent. Because this chemical is absorbed through the skin, parents have been reluctant to use it in children. Yet, after reviewing the studies, the American Academy of Pediatrics recommends that formulations containing no more than 30 percent DEET are safe for children and infants over two months of age. The Canadian Pediatric Society takes a more conservative approach and recommends parents not use a concentration higher than 10 percent DEET on children, and recommends against using DEET in infants under six months of age. Although the general consensus is that the 30 percent formulation of DEET can be used safely in infants and children, if you're still worried, you might want to spray DEET on your child's clothing instead of the skin before he goes out to play in a mosquito-prevalent area.

The information about West Nile Virus seems to be changing rapidly. Much of the information I've given you is from the most current publication of Pediatrics (the May 2004 issue), the official journal of the American Academy of Pediatrics. You can find the most updated information concerning WNV on the government website from the Center for Disease Control: