WEST NILE VIRUS
West Nile Virus (WNV) is a mosquito-borne virus that cycles between mosquitoes and birds. Birds develop high levels of virus in their blood, allowing mosquitoes to become infected and continue transmission. Only infected mosquitoes spread the virus through bites to humans and other animals. WNV was first identified in 1937, detected in the U.S. in 1999, and reached Utah by 2003. It now appears seasonally in Southwest Utah, and mosquito surveillance programs monitor local mosquito populations for infected mosquitoes to guide prevention.
PREVENTION, SYMPTOMS, AND CARE
Select a topic below to learn more about WNV:
PREVENTION
The best way to reduce risk is to avoid mosquito bites and eliminate standing water where mosquitoes can breed.
Reducing breeding areas may include:
- Unclogging roof gutters.
- Emptying swimming pools and removing any standing water from pool covers.
- Changing the water in pet bowls and bird baths regularly.
- Removing tires and other containers from outside that can hold water.
Reducing exposure may include:
- Avoiding unnecessary outdoor activity when mosquitoes are most active, including dawn, dusk, and early evening.
- Wearing clothing that covers as much skin as possible.
- Using EPA-approved insect repellent.
- Leaving areas with high mosquito activity as quickly as possible.
Important: West Nile virus is only spread through the bite of an infected mosquito.
SYMPTOMS
Most people infected with WNV do not develop symptoms. When symptoms do occur, they are usually mild.
Mild symptoms may include:
- Fever
- Mild headache
- Body aches
- Joint pain
- Nausea
- Vomiting
- Rash
Severe symptoms may include:
- High fever
- Severe headache
- Neck stiffness
- Disorientation
- Sudden weakness
- Vision loss
- Paralysis
Important: Contact a healthcare provider if you are concerned about a possible WNV infection.
DIAGNOSIS
Healthcare providers diagnose WNV based on symptoms, possible exposure to mosquitoes, and laboratory testing.
Diagnosis may include:
- Review of signs and symptoms
- History of recent mosquito exposure
- Blood tests to detect antibodies
- Cerebrospinal fluid (CSF) testing in more severe cases
Important: Laboratory testing helps confirm infection and rule out other causes of illness.
TREATMENT
There are no specific antiviral medications or vaccines for WNV.
Treatment may include:
- Rest
- Fluids
- Over-the-counter pain relievers to reduce symptoms
- Supportive medical care for severe cases
Important: All treatment decisions should be made by a healthcare provider.