State health officials say West Nile virus is showing up in mosquitoes unusually early this year.
The Colorado Department of Public Health and Environment said Thursday the virus has been found in mosquitoes in Adams, Boulder, Delta, Mesa and Weld counties.
Officials say it's likely to be found in other counties as well.
Last year, Colorado reported 322 cases of West Nile virus disease, and seven people died.
Humans can contract the virus from mosquito bites.
Initial human symptoms can include fever, headache, nausea, vomiting, muscle aches, weakness and rash. More severe symptoms can include stupor, disorientation, coma, tremors, vision loss, paralysis and even death.