The last human case reported in Cascade County was in 2015, according to a press release from the Cascade City-County Health Department.
He added that while most people do not become ill if they are bitten by a mosquito carrying West Nile, older people are more at risk.
"The amount of virus we are detecting in mosquitoes is well above the historical average for this time of year and is also occurring earlier in the season than the average", Mark Clifton, the agency's director, said in the release.
Cases generally tend to spike during the summer and fall months, between June and September, when activity is the most common. The first mosquitoes to test positive this year for West Nile were found in late May in Glenview and Morton Grove.
The CCHD says that the infected person is over the age of 65 and was exhibiting WNV symptoms, which led to being tested, but is not able to release any other patient-specific information due to privacy laws.More news: Samsung announces multi-billion dollar investment in AI, 5G, and more
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Although there is no vaccine to protect against West Nile Virus, over-the-counter pain medication can help treat symptoms such as fever. Less than one per cent develop more serious central nervous system issues, she said.
The cases, mostly in the western suburbs of Athens, mark a reappearance of the virus after an outbreak previous year when Greek authorities registered 48 cases, resulting in five deaths.
'Until the state's first hard frost, whether it's for work or play, being outside means there's a risk for West Nile virus'.
State officials recommend people use mosquito repellent and wear protective clothing.
West Nile virus is a viral infection found in birds and carried by mosquitoes which feed upon infected birds.