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Mesa County Public Health encourages people to take precautions to limit mosquito bites as mosquito season begins. Prevention is crucial when it comes to avoiding West Nile virus, which is spread to people by the bite of an infected mosquito. 

The West Nile virus season runs from May through October with case counts typically peaking in September. 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. 

“West Nile virus infections can often go unnoticed as many people may not show any symptoms or only experience mild ones like fever and headache. It's possible to be infected without realizing it,” said Epidemiologist Kathleen Satterfield. “However, in certain cases, especially among older adults or those with weakened immune systems, West Nile virus can lead to serious and even life-threatening complications such as encephalitis or meningitis. Unfortunately, there's no way to predict how an individual will respond if they contract the virus.” 



“Now is the time to think about prevention. There are simple, effective things you can do to lower your risk for mosquito bites to protect you and your family from West Nile virus. Prevention is key because there is no specific treatment for this virus if you get it,” said Satterfield. 

We recommend these steps to limit risk for mosquito bites:

  • 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.

Talk to a health care provider if you develop a fever with severe headaches or confusion.



Last year was a severe year for West Nile Virus in Colorado. There were 18 cases in Mesa County, and 13 of those people were hospitalized. According to the Colorado Department of Public Health and Environment (CDPHE), 634 cases of West Nile virus were reported across Colorado in 2023. Statewide, 386 people were hospitalized and 51 people died.











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A close up image of a mosquito on skin.