First West Nile Case in Jefferson_County,_Colorado

The first human case of West Nile virus for the 2026 season has been confirmed in a resident of United States — Jefferson County, Colorado. Health officials, including the United States — Colorado Department of Public Health and Environment and James Rada from United States — Jefferson County, Colorado, are urging residents to take precautions against mosquito bites, despite earlier dry weather. The virus, spread by infected mosquitoes, typically causes mild symptoms but can lead to severe neuroinvasive disease in about 1% of cases, particularly for individuals aged 55 and up or those with compromised immune systems. In 2025, United States — Colorado reported 286 human cases, 144 hospitalizations, and 18 deaths. Prevention methods include using insect repellent, wearing protective clothing, eliminating standing water, and ensuring window screens are in good repair. The United States — Centers for Disease Control and Prevention advises symptomatic treatment as there is no cure or vaccine.