West Nile virus has been confirmed in mosquitoes trapped in two new Arizona counties.
Mosquitoes trapped last month in Pima and Yavapai counties have both tested positive for the disease.
Yavapai County health officials said the mosquitoes that tested positive for the disease were trapped Aug. 14 between Chino Valley and Paulden.
In Pima County, the mosquitoes that tested positive were collected by the Indian Health Service near Kitt Peak Observatory on the Tohono O’odham Reservation.
Tribal Chairman Vivian Juan-Saunders said she has ordered tribal health officials to work with other government agencies to prevent the spread of the disease.
West Nile virus first made an appearance in Arizona this year.
About 80 percent of those who are infected will not show any symptoms. Those who develop symptoms usually display mild ones such as fever, body aches, nausea or skin rashes. About one in 150 people will develop a severe case that can lead to death.