As of the state's Sept. 30 update, Colorado had counted 56 cases of West Nile virus this year, 16 of them in Montrose County, more than twice as many as any other county, according to the Colorado Department of Public Health and Environment.
"We are the highest at this point in the state of Colorado," said Jackie Davis, Montrose County's public health director since late August. She previously led Delta County's health department, where KVNF interviewed her in 2024. On Sept. 16, Davis told the county's Board of Health that two people in the county had died of the virus this season.
The two counties have led before. Since the state began counting cases in 2003, Delta County has had the most in Colorado three times, in 2012, 2019 and 2020, and in 2022 Montrose County tied Boulder County for the most, with 38. Per resident, a KVNF analysis of state case counts and Census Bureau estimates for 2016 through 2025 found Delta County had Colorado's highest West Nile rate, about 11 times the statewide rate, and Montrose County the second highest, about six times.
Davis said the area has "the weather and the conditions that allow mosquitoes to thrive," from irrigation to a temperate climate. "Mosquitoes become infected when they feed on infected birds," she said. In Colorado, the main mosquito involved is Culex tarsalis, and CDC scientists in Fort Collins found these mosquitoes feed mostly on robins and doves. It doesn't spread from person to person except rarely, the CDC says.
Last month, KVNF reported on how Delta County's mosquito districts trap mosquitoes and have them tested, to find the virus before people get sick. Asked whether Montrose County has a surveillance program, Davis said, "We don't have one at this time." She said the county will look at programs to see whether it's something it can do. Even with surveillance, she said, the primary thing "is going to be about prevention and making sure that you are taking those precautionary steps."
Montrose County Public Health says most infected people never develop symptoms, about 20 percent get flu-like symptoms and fewer than 1 percent become seriously ill. Adults over 60 and people with certain medical conditions face greater risk, and anyone with severe symptoms, such as a severe headache or confusion, should contact a health care provider. There's no vaccine for people. "There is for horses, but not for humans," Davis said.
Davis sums up prevention as the four D's: drain standing water, dress to cover your skin, stay inside at dusk and dawn, and defend yourself with insect repellent. She recommends draining standing water weekly, since a mosquito develops in about 7 to 10 days. With fall coming, she said, "it's not a time to put your guard down."
For water you can't drain, Montrose County Public Health gives away mosquito dunks, a larvicide, while supplies last, at 1845 S. Townsend Ave. in Montrose. Delta County Public Health has them at 255 W. Sixth St. in Delta.
