The weather in Utah is cooling off, but the threat of obtaining West Nile Virus from a mosquito bite still exists.

Summer may be over, but it’s too soon to let down your guard when it comes to preventing West Nile Virus from mosquito bites.

Dr. Heather Heileson, an Emergency Department physician at McKay-Dee Hospital, says that of the 40 cases of West Nile Virus discovered in Utah this year, 15 came last week, and the risk of obtaining West Nile from a mosquito bite will remain high for several weeks. 

“It’s really ramping up right now,” she says, noting that recent rains have resulted in pools of water that are essentially new mosquito breeding grounds. “This time of year we are seeing a spike.”
Although Dr. Heileson says that “70 to 80 percent of people with the virus will never know they have it,” three people have died from West Nile Virus in Utah this year. Last year, of the 13 known cases who contracted West Nile in Utah, one died.

“With three deaths already this year, it suggests a higher mortality rate from West Nile Virus,” Dr. Heileson says. That may be due in part to a wet spring that triggered an increase in the number of mosquitoes across the state.

The disease tends to affect those older than 65 particularly hard, but two of the three people who died this year were middle-aged.

Reports in Utah of West Nile Virus cases in humans have dropped dramatically from 2006, when 174 cases were recorded. Dr. Heileson attributes the decrease primarily to fewer people being formally tested and diagnosed, not an actual reduction in the number of infections. When the disease was found in Utah in 2003, only a handful of cases were discovered. As people became aware of the risks, more came in for testing, she says, resulting in the high 2006 numbers. Now fewer people may be going in for tests for mild symptoms, but the cases discovered tend to be serious because those that seek treatment and testing tend to be sicker.

Currently there are no vaccines to prevent or medications to treat West Nile in humans — a vaccine for horses does exist — but Dr. Heileson says research is currently being done for a human vaccine. She recommends that anyone experiencing severe headaches, mental status changes or confusion, severe vomiting and/or diarrhea resulting in dehydration, vision changes, unusual lethargy or a stiff neck be examined by a doctor.

Mosquitoes carrying West Nile Virus have been found in most corners of Utah. As always, prevention is the best defense against the disease, and the Centers for Disease Control and Prevention recommends the following to avoid mosquito bites:

• Apply and reapply insect repellent as directed (DEET is not recommended for infants under 2 months old and oil of lemon eucalyptus (OLE) or para-menthane-diol (PMD) is not recommended for children under 3 years old).
• Do not apply insect repellent onto a cut or irritated skin and be careful not to get it into your eyes or mouth.  Spray repellent onto your hands and then carefully apply it to your face.  
• Dress yourself and children in longsleeves and pants when outdoors and wear several layers of clothes, if possible, to prevent bites to the skin through the clothing.
• Cover crib, stroller, and baby carrier with mosquito netting.  Sleep in a zipped tent when camping.
• Use tightly fitting screens on windows and doors. Repair holes in screens to keep mosquitoes outside.
• Once a week, empty and scrub, turn over, cover, or throw out items that hold water, such as tires, buckets, planters, toys, pools, birdbaths, flowerpots, or trash containers. Check inside and outside your home for any free-standing water as mosquitoes lay eggs in and around stagnant water.