CDPHE UPDATE: West Nile virus detected in humans in Colorado

Take precautions to avoid bites

REMOTE (August 13, 2021): Colorado Department of Public Health and Environment (CDPHE) is reporting West Nile virus (WNV) in humans in Colorado for the first time this season. One case is from Larimer County and the other case is from Delta County. Both cases have survived and are recovering from their illnesses at the time of the investigation. West Nile virus is most commonly spread to people by the bite of an infected mosquito. WNV-positive mosquitoes have been found in Adams, Boulder, Delta, Denver, Larimer, and Weld counties this year.  

“There are simple precautions people can take to protect themselves from West Nile virus,” said Dr. Jennifer House, deputy state epidemiologist and public health veterinarian. “Use an effective insect repellent, wear protective clothing, or stay indoors when mosquitoes are active, and mosquito-proof your home.” 

In Colorado, most human West Nile virus cases are reported in August and September.

In 2020, Colorado had 35 reported human cases of West Nile virus, including one death.

Most people infected with West Nile virus don’t have symptoms. About 20% of infected people will have flu-like symptoms, and fewer than 1% develop a serious, potentially deadly illness. People over age 60 and those with certain medical conditions are at greater risk of serious illness. See a health care provider if you develop severe headaches or confusion.

To protect yourself:


  • Use insect repellents when you go outdoors. Repellents containing DEET, picaridin, IR3535, and some oil of lemon eucalyptus, and para-menthane-diol products provide the best protection. Follow label instructions.
  • Limit outdoor activities at dusk and dawn, when mosquitoes that carry West Nile virus are most active.
  • Wear protective clothing (long pants, long-sleeved shirts, and socks) in areas where mosquitoes are active. Spray clothes with insect repellent for extra protection.

To mosquito-proof your home:

  • Drain standing water around your house at least once every week. Empty water from tires, cans, flowerpots, clogged gutters, rain barrels, birdbaths, toys, and puddles.
  • Install or repair screens on windows and doors.

For more information, visit the department’s West Nile virus web page

By Brian Allmer - The BARN

Brian Allmer & the BARN are members of the National Association of Farm Broadcasting (NAFB), the Colorado FFA Foundation, the Colorado 4H Foundation, the Colorado Farm Show Marketing Committee, 1867 Club Board Member, Denver Ag & Livestock Club Member, the Weld County Fair Board, the Briggsdale FFA Advisory Council, Briggsdale 4H Club Beef Leader & Founder / Coordinator of the Briggsdale Classic Open Jackpot Show.