The Weld County Department of Public Health and Environment (WCDPHE) has been notified of a case of West Nile Virus (WNV) in a Weld County resident. This is the first case of the 2026 mosquito season in Weld County and comes a month later than in 2025. Last year there were 34 cases of WNV investigated in Weld County.
This year, the number of culex mosquitos (those that transmit WNV) trapped is lower than the 5-year average. However, Culex mosquitoes are currently making up approximately 80 percent of mosquitoes that have been trapped in the three sentinel zones in Weld County, which includes the Greeley, Evans, Kersey, LaSalle area, the Johnstown, Milliken, and Platteville area, and the Firestone, Dacono, and Fort Lupton area. These mosquito traps are monitored on a weekly basis and mosquitoes in all three zones have tested positive for WNV.
