Health officials say a bird collected from Johnsburg last week has tested positive for West Nile virus, the first bird to test positive in McHenry County this year.
A blue jay was collected from Johnsburg on July 18 and subsequently tested positive for West Nile virus, the McHenry County Department of Health (MCDH) said this week.
All other prior bird samples have been negative this year.
The health department said they collect a limited number of birds for testing each mosquito season.
The West Nile virus surveillance is conducted throughout the county from May to October.
West Nile virus can be transmitted to birds through the bite of an infected mosquito, health officials say.
Infected birds can become carriers of the virus by passing it to mosquitos that bite them.
In Illinois, the virus can be transmitted to humans through the bite of an infected Culex species mosquito.
Illness from West Nile virus is usually mild and includes fever, headache and body aches but serious illnesses, such as encephalitis and meningitis and death, are possible.
Those 60 years of age or older or who have serious underlying health conditions are at higher risk for developing severe symptoms.
The MCDH said mosquitoes typically breed in stagnant water high like abandoned swimming pools, bird baths, buckets, clogged gutters and rimless tires.
“The first and best defense against mosquito-borne illness is to eliminate potential mosquito breeding sites on your property by emptying standing water from containers around the house and making sure doors and windows have tight-fitting screens,” the MCDH said.
Health officials also recommend residents use insect repellents approved by the EPA.