Colorado reports its first West Nile virus case in humans this year

Colorado health authorities reported the first human case of West Nile virus in the state this year on Monday, as cases are confirmed across the nation. 

The Department of Public Health & Environment said the case was found in an individual from La Pata County, as well as in mosquitoes in seven counties.

“Mosquito populations are at historic levels in some parts of the state due to the high rainfall this year. This unusually high mosquito activity along with known presence of the virus has caused an elevated risk of West Nile virus transmission to humans,” the department warned. 

Last year, Colorado had more than 200 reported human cases of West Nile virus, including 20 deaths. 

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Matthew Vanderpool, environmental health specialist and entomologist for the Louisville Metro Department of Public Health and Wellness, displays a mosquito collected earlier in the day on August 25, 2021, in Louisville, Kentucky. (Photo by Jon Cherry/Getty Images)

This advisory comes after cases were detected in a man from Tulare County, California, and a man in Dallas County, Texas. 

The California Department of Public Health cautioned in June that residents should take extra precautions following heavy rain there leading to population increase. 

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A Durango, Colorado, street view. (Photo by Santi Visalli/Getty Images)

The U.S. Centers for Disease Control and Prevention, which tracks such cases across the country, had reported 47 West Nile virus human disease cases this year as of July 18. 

The agency showed more than 1,125 human disease cases in 2022. 

Cases of West Nile virus occur during mosquito season, which starts in the summer and continues through fall. 

A 3D illustration of the West Nile virus, a virus that is transmitted by mosquito and causes West Nile fever. (iStock)

There are no vaccines to prevent or medications to treat the virus — a member of the flavivirus genus — in people, but the CDC notes that most people infected with it do not feel sick. 

Around one in five of those who are infected develop a fever and other symptoms, and about 1 out of 150 infected people develop a serious and sometimes fatal illness.