West Nile Virus

By Alan Peterson, M.D.

The CDC recommends that we do the following:

1. To avoid helping mosquitoes breed in your environment, drain standing water.  Routinely empty water from flowerpots, pet bowls, clogged rain gutters, swimming pool covers, discarded tires, buckets, barrels, cans and other items that collect water in which mosquitoes can lay eggs. 
2. Apply insect repellent to exposed skin.  The more DEET (N,N-diethyl-m-toluamide) a repellent contains, up to 50%, the longer time it can protect you from mosquito bites.  If you buy the product (OFF) that is between 20 and 30% DEET, a recent New England Journal of Medicine article stated that it was excellent for providing eight hours of protection.
3. Repellents may irritate the eyes and mouth, so avoid applying repellent to the hands of children. 
4. Whenever you use insecticide or insect repellent, be sure to read and follow the manufacturer’s directions for use, as printed on the product.
5. Spray clothing with repellents containing permethrin or DEET since mosquitoes may bite through thin clothing.  Do not apply repellents containing permethrin directly to exposed skin.  If you spray your clothing, there is no need to spray repellent containing DEET on the skin under your clothing.   Any exposed skin though should be sprayed with DEET.
6. When possible, wear long-sleeved shirts and long pants whenever you are outdoors. 
7. Place mosquito netting over infant carriers when you are outdoors with infants.
8. Consider staying indoors at dawn, dusk, and in the early evening, which are peek mosquito-biting times.
9. Install or repair window and door screens so that mosquitoes cannot get indoors.

Most people with WNV will have either no symptoms or only mild ones.  In the 1999 outbreak in New York, 2.6% of residents had been infected but only about 1 in 5 infected persons developed a fever with the illness.  Symptoms begin three to fourteen days after the bite of an infected mosquito and, along with fever, may include headache and muscle aches, and occasionally skin rash and swollen lymph glands.  Only one out of every 150 infected persons develops encephalitis marked by headache, high fever, neck stiffness, disorientation, coma, tremors, or convulsions.