UPDATED SEPTEMBER 22, 2022: There is a second confirmed case of West Nile virus in Mesa County.

Local Situation

For the first time this season, a human case of West Nile virus has been confirmed in Mesa County. A male in his 60s has been diagnosed with neuroinvasive West Nile virus. He is currently hospitalized. Neuroinvasive West Nile virus is a severe form of the disease, which may include encephalitis or meningitis.

Mesa County Public Health tracks West Nile virus cases in the county. Our partner, the Grand River Mosquito Control District, monitors mosquito activity in the Grand Valley.


Regional & State Situation

Montrose and Delta Counties are experiencing an increase in West Nile virus cases compared to previous years. This year, 40% of the cases reported in Colorado have involved residents of Montrose County or Delta County. According to the Colorado Department of Public Health and Environment, there have been 63 cases of West Nile virus statewide this year, including five deaths. So far this season, health officials are seeing increased mortality with 7.7% of reported cases resulting in death.



There is no treatment for West Nile virus, so prevention is key. This is the time of year when mosquito activity typically peaks, so it’s important for residents to take precautions. The best way to avoid getting West Nile virus is to avoid being bitten by mosquitoes. Increased outdoor activity can lead to increased exposure to mosquito bites so take some easy steps to protect yourself:

  • Use an EPA-approved insect repellent effective against mosquitoes. Look for one that contains DEET, Picaridin, IR3535, 2-undecanone, or oil of lemon eucalyptus.
  • Dress in long sleeves and pants when in areas where mosquitoes are active.
  • Avoid being outdoors at dusk and dawn; this is when mosquitoes are most active.
  • Drain and remove sources of standing water on your property.



The West Nile virus season runs from May through October with case counts typically peaking in September. Of the cases investigated in 2022 in Colorado, 60% have been neuroinvasive and 67% have required hospitalization. Neuroinvasive infections cause symptoms like fever, seizures, altered mental status, movement disorders, rigidity, and other neurologic deficits.

Most people who are infected with West Nile virus do not get sick. In fact, about 75-80% of cases are asymptomatic. For those who do experience symptoms, they can range from mild illness to severe encephalitis, which is inflammation of the brain. People who are over the age of 50 are at the highest risk for severe illness. This is not a condition that spreads from person-to-person.