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Colorado’s first human case of West Nile virus in 2024 detected in Arapahoe County

Mosquitoes in Longmont test positive for West Nile Virus
Posted at 12:40 PM, Jun 26, 2024

DENVER — Colorado’s first human case of West Nile virus this year has been confirmed in an Arapahoe County resident, state health officials announced Wednesday.

The county’s health department is warning residents to take precautions as the state does not typically see cases this early in the season. The Colorado Department of Public Health and Environment (CDPHE) says most human cases of West Nile virus are reported in August and September.

“While we know that West Nile virus is endemic to Colorado—meaning we expect to see some cases each year—we never quite know how many to expect or just how bad a season will be. What this first case confirms for us, however, is that West Nile virus is present in our mosquito population, and as mosquito numbers increase, the risk of West Nile virus will, too,” said Arapahoe County Public Health official Melissa Adair in a news release. “We’re encouraging all Arapahoe County residents to take precautions now, before we see mosquitoes and illness increase this season.”

While most people infected with West Nile Virus don’t experience symptoms, some can become seriously ill and even die, according to the CDPHE. People aged 60 years and older and those with certain medical conditions are at greater risk of serious illness, officials said.

Last year was Colorado’s worst for West Nile virus in 20 years, with 631 cases spanning 40 counties, including 383 hospitalizations and 50 deaths, the CDPHE said in a news release. Arapahoe County alone saw 56 cases.

To protect yourself, the agency recommends:

  • Wear an EPA-approved insect repellant, such as one that includes DEET. These repellants are proven safe and effective for all people ages 2 months and up, including those who are pregnant and breast/chest feeding. Learn more about tips for choosing and applying insect repellent for children.
  • Stay indoors at dawn and dusk when mosquitoes are most active. 
  • Avoid recreating around standing water sources, such as lakes and ponds. If you are camping, use mosquito netting and/or insect repellent. 
  • Wear clothes to protect against mosquitos, such as long-sleeves and pants.
  • Drain standing water sources including puddles, gutters, flowerpots, tires, pool covers, boats and tarps. 
  • Prevent mosquitoes from getting indoors by utilizing an air conditioner or fans, rather than open windows, and if you do have any windows or doors with openings, utilize a screen. 
  • If you live on a property with a septic system, take steps to prevent mosquitoes by ensuring your tank is in good repair and any vents or openings are covered or sealed. 

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