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West Nile Virus: What You Need To Know

Post Date:07/19/2017 3:04 PM

Salt Lake County Health Department received results of a mosquito pool in Sandy City that has tested positive for West Nile Virus. ("Mosquito pool" is the term used for a group of mosquitoes caught and tested out of a single trap—it is unrelated to swimming, wading, or landscape pools.) This positive pool is the second in Salt Lake County this season (following one in Draper two weeks ago), and is joined by another new positive pool in western Salt Lake City. As most mosquitoes have a flight range of 3-4 miles, the exact address of the trap that gave us positive results is not particularly useful; the important thing to know is that there are mosquitoes with West Nile Virus present in Salt Lake County in the Sandy area.

The Salt Lake County Health Department does not have any confirmed human cases of West Nile Virus reported to date, but this is a good reminder that it is important to protect yourself from mosquito bites, particularly in the hours from dusk to dawn:

  • Use a mosquito repellent with DEET, permethrin, picaridin, IR3535 or oil of lemon eucalyptus according to package directions.
  • Drain standing water in yards (old tires, potted plant trays, pet dishes, toys, buckets, etc.).
  • Wear long sleeves and pants after dusk.
  • Keep roof gutters clear of debris.
  • Clean swimming pools often or drain them.
  • Clean and stock garden ponds with mosquito-eating fish or mosquito dunks.
  • Make sure screen doors and window screens are in good condition so that mosquitoes cannot get indoors.
  • Keep weeds and tall grass cut short; adult mosquitoes look for these shady places to rest during the hot daylight hours.
Sandy is in the South Salt Lake Valley Mosquito Abatement District ( Residents with ornamental ponds, horse troughs, or other standing water they are concerned about can contact the district to ensure the entomologists are aware of that specific potential mosquito breeding ground; residents can also request mosquito prevention treatments be applied to their ponds or troughs at no cost to them.


More information about West Nile Virus from the Health Department:

What is West Nile virus?

West Nile virus (WNV) infection is a mosquito-borne illness that can be very serious and, in some cases, cause death. West Nile virus was first found in the United States in 1999 in Queens, New York.


What are the symptoms of West Nile virus infection?

Most people will have no symptoms at all. Approximately 80 percent of people infected with WNV will not have any signs or symptoms, but there is no way to know in advance if you will develop severe illness or not.

Some people will have milder illness. Up to 20 percent of the people who become infected will display symptoms that may include fever, headache, body aches, nausea, vomiting, and sometimes swollen lymph glands. They may also develop a skin rash on the chest, stomach or back. Some people are sick for a few days, but even previously healthy persons have been sick for several weeks with infection.
A few people will have serious illness. About one in 150 people infected with WNV will develop severe illness. These symptoms can include high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness, and paralysis. These symptoms can last several weeks to months, and neurological effects may be permanent.


How does West Nile virus spread?

WNV is spread primarily through the bite of an infected mosquito. Mosquitoes become infected when they feed on infected birds, and infected mosquitoes can then spread WNV to humans when they bite.

What is the treatment for West Nile virus infection?

There is no specific treatment for WNV infection. People with mild infections recover on their own. People with severe symptoms require hospitalization. Some people who develop severe illness may die from the infection.

How soon do infected people get sick?

People usually develop symptoms within 3 to 14 days after they are bitten by an infected mosquito.

Who is at risk of getting severe West Nile infection?

People who are over the age of 50, are immunocompromised, or have diabetes are at higher risk of having serious symptoms and illness from WNV. These individuals should be especially careful to avoid mosquito bites.

What should I do if I think I have a WNV infection?

If you develop symptoms of WNV infection you should see your doctor. If the signs and symptoms are severe, such as unusually severe headaches or confusion, seek medical attention immediately. Severe WNV illness usually requires hospitalization. Pregnant women and nursing mothers are especially encouraged to talk to their doctor if they develop symptoms that could be WNV.


For more information, please contact the Salt Lake County Health Department at 385-468-4100 or