Weld County confirms first West Nile case of 2026
Weld County has confirmed its first West Nile virus case of the 2026 mosquito season, a month later than last year’s first case. Mosquitoes in all three county sentinel zones have tested positive, prompting health officials to urge precautions.
The Weld County Department of Public Health and Environment has been notified of the county’s first West Nile virus case of the 2026 mosquito season, the county said. The case comes a month later than the first case in 2025. The county investigated 34 cases last year.
The number of Culex mosquitoes trapped this year is below the five-year average, but the species currently accounts for about 80% of mosquitoes caught in the county’s three sentinel zones. Mosquitoes in all three zones have tested positive for West Nile virus. The zones cover areas around Greeley, Evans, Kersey and LaSalle; Johnstown, Milliken and Platteville; and Firestone, Dacono and Fort Lupton.
Symptoms can appear three to 14 days after infection. Most infected people do not have symptoms, but possible symptoms include fever, headache, nausea and vomiting, muscle aches and weakness, and rash. People who develop symptoms should contact a health care professional immediately, the county said.
The county recommends draining standing water around homes weekly, limiting outdoor activity and taking precautions at dusk and dawn, using insect repellent and wearing long sleeves, pants and a hat in areas where mosquitoes are active.