Boulder County Public Health confirmed that, last week, mosquitoes trapped on the east side of Niwot tested positive for West Nile. No other testing sites returned positive results.

Mosquito samples collected in six areas in Allegheny County have tested positive for West Nile Virus, according to the county's health department Friday.

Boulder County Public Health and Weld County both confirmed within two days that there have been the first positive tests of West Nile virus in mosquitoes in those counties.