 It's the first West Nile case of the year in Colorado. The case was confirmed in Arapahoe County, and public health officials are concerned because typically Colorado doesn't see its first human case of West Nile until later in the summer. As mosquito numbers increase, the risk of West Nile virus will, too. Last year was Colorado's worst for West Nile in 20 years, with over 600 cases in 40 counties, including 50 deaths. 2023 saw nearly as many cases as the last 50.