SOUTHERN UTAH — West Nile virus was found in mosquitoes collected last week by the Moab Mosquito Abatement District in the Matheson Preserve northwest of Moab.

West Nile virus is an arthropod-borne virus (arbovirus) most commonly spread by infected mosquitoes, according to the Centers for Disease Control and Prevention. It can cause febrile illness, encephalitis (inflammation of the brain) or meningitis (inflammation of the lining of the brain and spinal cord).

The virus is transmitted by Culex mosquitoes that bite at night anywhere in the valley or during mild periods of the day in the bulrush marshes of the Preserve, according to a statement issued Monday by the Grand County Sheriff’s Office.

The peak flight time for these mosquitoes is during the two hours after the first stars become visible at sunset.

The virus can cause disease in humans, birds, horses and some other mammals. The most common way to get infected is through the bite of a mosquito.

Most people – 70-80 percent – who become infected with West Nile virus do not develop any symptoms, according to the health.Utah.gov website.

The most serious cases can lead to hospitalization, disability or death. Symptoms of the severe form of West Nile virus include: high fever, severe headache and stiff neck, disorientation and confusion.

Proper diagnosis of West Nile virus disease is important, Grand County officials said. The incubation period is usually one to two weeks, and many other viruses – from herpes to influenza – can cause similar symptoms including encephalitis.

Ways to help prevent the spread of West Nile virus:

• Avoid outdoor activities, such as gardening, at dusk when mosquitoes are most active.
• If outside during the periods when mosquitoes are most active, cover up by wearing long-sleeved shirts, pants, shoes and socks.
• Use mosquito repellents with DEET. Follow product directions for children and how often it should be applied.
• It is especially important to prevent night mosquito bites by having good window screens and by using a screened tent if sleeping outside.
• Eliminate standing water in tires or similar water-holding containers as these may serve as mosquito breeding sites. Change the water in birdbaths at least weekly.

Culex mosquitoes breed in water that stands for more than a week. Unmaintained swimming pools, hot tubs, wading pools, water filled buckets, livestock water troughs and flood-irrigated fields breed these mosquitoes. If people remove stagnant water from their property and irrigators properly manage their water, fewer Culex will be produced.

Currently, Culex numbers outside the marsh are very low and below the District’s spray threshold, but surveillance will continue to see if there are any changes, according to the Sheriff’s Office. If insecticide spraying (fogging) is needed, it will be done at that time and in those areas where Culex numbers pose significant risk.

“Because of declining mosquito numbers and the imminent arrival of fall, spraying of adult mosquitoes is not likely,” officials said. “However, if spraying is needed, it will be based on local Culex mosquito trap counts and infection rates.”

Resources

• Centers for Disease Control and Prevention – West Nile Virus

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