West Nile virus is on the rise in Northern Colorado.
Weld, Boulder, Adams, Delta and Mesa counties have all reported finding Culex mosquitoes infected with the disease, the Larimer County Health Department reported Tuesday.
In June, Boulder County Public Health said mosquitos tested positive at Christensen Park near Kings Ridge Boulevard and Tom Watson Park on 63rd Street.
The City of Fort Collins has yet to detect infected mosquitoes or birds, Larimer County officials said Tuesday.
The disease is transmitted to humans by mosquitoes and symptoms may appear in 3 to14 days after infection, according to the Weld County Health Department.
Initial symptoms include fever, headache, nausea and vomiting, muscle aches, weakness and rash. Symptoms of severe illness include high fever, stupor, disorientation, coma, tremors, muscle weakness, vision loss, paralysis and even death.
About 75 percent of people who are infected have no symptoms, health officials said. About 25 percent will develop West Nile fever.
State health officials advise people take the "Four Ds" precautions against West Nile virus: