First Human Cases of West Nile Virus Reported in Colorado for 2025 in Adams County

In a recent health update, Colorado public health officials confirmed the state's first human cases of West Nile virus for 2025, identified in two residents of Adams County. The individuals likely contracted the virus from infected mosquitoes during late June. Despite no mosquitoes testing positive for West Nile in Adams County itself, neighboring counties have already reported positive mosquito tests, indicating the virus's early presence in the region.

Colorado's West Nile season started sooner than usual this year, with mosquitoes testing positive in areas such as Denver, Boulder County, Weld County near Greeley, and Johnstown earlier in July. While most infections are asymptomatic, roughly 20% of infected individuals experience flu-like symptoms, and less than 1% may develop severe, often life-threatening illnesses.

Older adults, particularly those over 60, and individuals with certain health conditions are at heightened risk for serious complications. Symptoms warranting medical consultation include severe headaches, confusion, or neurological changes.

Preventive measures focus on avoiding mosquito bites, which include applying insect repellent, wearing long-sleeved clothing, and reducing outdoor activity during dawn and dusk hours when mosquitoes are most active. Additionally, removing standing water from containers like birdbaths, rain barrels, or plant pots can help reduce mosquito breeding sites.

Health authorities emphasize the importance of early detection and prevention strategies to mitigate the impact of West Nile virus this season.

Source: https://medicalxpress.com/news/2025-07-colorado-human-cases-west-nile.html