Health officials have confirmed Fremont County's first human case of West Nile virus for the year, Gazette news partner KKTV reported.
The county health department did not say where in the county the case was reported.
More than 20 human cases of the virus have been reported in Colorado this year, including one fatal case in Fort Collins, according to the Colorado Department of Public Health & Environment.
West Nile virus is commonly spread by infected mosquitoes. Most people with the virus don't get sick, but about 20 percent who become infected have flulike symptoms; less than 1 percent develop a more serious illness that can be deadly.
The peak time of year for West Nile infections in Colorado is late May through the fall. This year, reports of infections peaked at the end of July and the beginning of August, the state health department reported. Data are not yet available for the first week of September.
El Paso County has not reported any cases this year. In 2016, it reported one case, compared with 23, 27 and 32 cases respectively in Boulder, Weld and Larimer counties, the U.S. Centers for Disease Control and Prevention reported. Fremont County did not report any cases in 2016.