Colorado Battles Alarming West Nile Virus Spike as Mosquito Populations Soar

As of August 5th, 2025, Colorado is facing a concerning spike in West Nile virus cases. The Denver Department of Public Health and Environment has confirmed the city's first human case of the virus this season, while officials in Jefferson County have also reported their initial human infections, with three people affected.

Across the state, there have been more than a dozen West Nile cases reported so far this year, tragically resulting in one death. The Colorado Department of Public Health and Environment has detected the virus in mosquitoes in eight of the 16 counties that have conducted testing, including major population centers like Adams, Arapahoe, and Denver.

The situation is particularly dire in Fort Collins, where the West Nile infection rate in mosquitoes is currently 11 times higher than the historical average and four times greater than it was in 2023. Authorities are urging residents to take precautions, such as eliminating standing water, using insect repellent, and limiting outdoor activity at dawn and dusk when mosquitoes are most active.

With the threat of serious symptoms, including fever, headaches, and even neurological complications, officials are advising anyone experiencing West Nile-related symptoms to seek immediate medical attention, especially those over 50 or with weakened immune systems who are at higher risk.