PHOENIX - Arizona continues to lead the nation in people infected with West Nile virus with 114 cases reported so far, state health officials said Thursday.
Maricopa County - where most of the cases have been reported - has had two deaths. A 74-year-old north Phoenix woman died of the mosquito-borne disease in June and a 69-year-old north Phoenix man died last week.
Pinal County has reported three cases and Graham and Mohave counties have each reported one human case each. In 11 of the state's 15 counties, health officials have found mosquitos and other animals that carry the virus.
"We have to assume that West Nile virus is present throughout the state," said Arizona Department of Health Services Director Catherine Eden. "People should not wait on reports of cases of West Nile in their communities before taking personal precautions. We are all at risk."
The virus is normally transmitted to humans and animals by mosquitos, which become infected when they feed on infected birds. Arizona saw its first case of West Nile last year. Fifteen cases were reported and one person died.
About 80 percent of people who are infected with the virus show no symptoms while 20 percent could develop symptoms such as fever, nausea, headache and muscle aches, health officials said. In rare cases, West Nile progresses to life-threatening encephalitis or meningitis.
Of the 114 cases reported in Arizona this year, 32 developed encephalitis, 40 got meningitis, 14 got West Nile fever and 28 were unknown. Those infected ranged in age from 3 months to 87 years old.
Health officials have warned people to get rid of standing water and other mosquito-breeding sites. They have also recommended the use of repellents that contain the chemical DEET.
Thirty-four states in all have reported some form of the virus in mosquitoes, birds, horses or people. Last year there were 9,862 West Nile cases and 264 deaths, the CDC said.