Health Dept Home
Environmental Health Home Regulations Library Food Handlers Permit Used Oil Recycling West Nile Virus
Food Establishment Enforcement Vehicle Emmisions Report A Smoking Vehicle Printable Forms  

WEST NILE VIRUS                                                          

West Nile Virus (WNV) is a flavivirus commonly found in Africa, West Asia, and the Middle East. It is closely related to St. Louis encephalitis virus which is also found in the United States. The virus can infect humans, birds, mosquitoes, horses and some other mammals. WNV was first recognized in the United States in 1999 in New York City.  It is not known how the virus was first introduced into the U.S., but since the initial appearance it has spread rapidly.


West Nile virus is spread by the bite of an infected mosquito, and can infect people, horses, many types of birds, and some other animals.


Symptoms include fever, headache, and body aches, occasionally with a skin rash on the trunk of the body and swollen lymph glands.  More severe infection may be marked by headache, high fever, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, paralysis, and, rarely, death.  Symptoms of mild disease will generally last a few days.

Symptoms of severe disease may last several weeks, although neurological effects may be permanent.


Here are preventive measures to take:

  • Apply insect repellent  exposed skin. The more DEET a repellent contains the longer time it can protect you from mosquito bites. A higher percentage of DEET in a repellent does not mean that your protection is better—just that it will last longer. DEET concentrations higher than 50% do not increase the length of protection. Choose a repellent that provides protection for the amount of time that you will be outdoors.
    • Repellents may irritate the eyes and mouth, so avoid applying repellent to the hands of children.
    • Whenever you use an insecticide or insect repellent, be sure to read and follow the manufacturer's DIRECTIONS FOR USE, as printed on the product.
  • 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.
  • When possible, wear long-sleeved shirts and long pants whenever you are outdoors.
  • Place mosquito netting over infant carriers when you are outdoors with infants.
  • Consider staying indoors at dawn, dusk, and in the early evening, which are peak mosquito biting times.
  • Install or repair window and door screens so that mosquitoes cannot get indoors.
  • To avoid helping mosquitoes breed in your environment, drain standing water. Routinely empty water from flower pots, 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.

Note: Vitamin B and "ultrasonic" devices are NOT effective in preventing mosquito bites.

West Nile Virus Links

U. S. Centers for Disease Control and Prevention (CDC)

Current Information on West Nile During Pregnancy and Breastfeeding

Information on West Nile and Blood Donations, Blood Transfusions and Organ Donations

U.S. Food and Drug Administration (FDA)

U.S. Geological Survey National Wildlife Health Center

Utah Department of Health, Office of Epidemiology

Utah Department of Agriculture and Food

West Nile

The American Mosquito Control Association

International Traveler’s Clinic

Mosquito Netting Information

U. S. Department of Agriculture


Harvard School of Public Health


National Pesticide Information Center


Skeeterbites  (Sponsored by Cutter Insect Repellents)


Off Insect Repellent West Nile Page