Colorado Confirms First West Nile Virus Death of 2025, 8 Counties Affected

West Nile virus continues to be a problem in Colorado. The first detection of West Nile virus was in late June in Larimer County. The detection was based on field research. At the time, no humans were infected.

READ MORE: First Case of West Nile Detected in Larimer County

Human Infections Now Confirmed in Colorado

A lot has changed since then. Some Colorado residents have been confirmed to have been infected with the West Nile virus. Unfortunately, one Colorado resident has died due to it.

First West Nile Death in Colorado in 2025

The Colorado Department of Public Health and Environment announced on July 25 that a person has died due to the West Nile virus. The individual was an adult residing in Lafayette.

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Colorado Department of Public Health and Environment did not announce the resident's age or name. Just the fact that they lived in Lafayette.

West Nile Virus Found in Mosquitoes Across Colorado

They also said that the West Nile virus is active in the majority of Colorado this year already. Here is the list of counties that have had mosquitoes test positive.

• Adams County
• Arapahoe County
• Boulder County
• Broomfield County
• Denver County
• Jefferson County
• Larimer County
• Weld County

Common Symptoms of West Nile Virus to Watch For

The Colorado Department of Public Health and Environment says that most people will not develop symptoms of West Nile virus. However, here are the symptoms.

West Nile virus is most commonly spread to people by the bite of an infected mosquito. Symptoms typically appear three to 14 days after being bitten and may include fever, severe fatigue, headache, body aches, skin rash and swollen lymph nodes.