All have the non-neuroinvasive form of the illness.
The department found mosquito pools positive for the West Nile Virus in the following zip codes: 38002, 38016, 38053, 38104, 38106, 38108, 38109, 38111, 38112, 38114, 38115, 38116, 38117, 38118, 38119, 38122, 38127, 38128, 38133 and 38135.
"Persons over age 50 and those with compromised immune systems are at higher risk of developing severe illness if infected with West Nile Virus", Health Department Director Alisa Haushalter said.
Arizona continues to report some 75 percent of the human WNV cases in the United States and according to the Arizona Department of Health has reported a total of 100 confirmed and probable cases and one fatality, almost all the cases in Maricopa County.
West Nile virus activity became widespread enough in Davis previous year that officials with the Sacramento-Yolo Mosquito & Vector Control District briefly considered aerial insecticide spraying over the city in mid-August. As such, the CDC recommends wearing bug spray when spending time outside, and treating outdoor gear with insect-repelling permethrin.
"With the warmer temperatures we've seen recently West Nile virus activity continues to increase", said Gary Goodman, manager of the Sacramento-Yolo district.
Two people tested positive for West Nile Virus in Fresno County at the end of July, according to the county's public health department, and five others were suspected of carrying the virus.
When mosquito activity rises to a level considered unsafe for public health, Sacramento-Yolo mosquito district officials have conducted aerial spraying in the past.
"This is the second year in a row that we've found pools of mosquitoes that contain the West Nile virus", St. Joseph County Health Officer Dr. Luis Gallup said.
Use mosquito repellent, following label directions carefully. Wear proper clothing and repellent if outside during these times. At home, look for holes in screens or windows that allow pests to get indoors.
Drain Standing Water - Mosquitoes lay their eggs in standing water. Fix or replace screens with tears or holes. Crows and magpies are particularly susceptible to the disease, so they make excellent early warning sentinels for virus activity in the area, the vector control district said.