The first bird to test positive for the West Nile virus in DuPage County was found in Glen Ellyn last week, according to the Illinois Department of Public Health.
Already this year, dead birds infected with the virus have been found in seven other counties, including Kane, Cook, Champaign and Vermilion. The first infected birds in Illinois were found last year, but so far, there have been no human cases in the state.
The virus can be transmitted to humans who are bitten by an infected mosquito that had previously bitten an infected bird or mammal. Health officials say that a small percentage of people exposed to the virus will become sick, but they urge residents to take precautions against exposure to the virus, which is lethal to birds.
Since the virus was found in the United States in 1999, it has killed 18 people, according to the Centers for Disease Control and Prevention in Atlanta.
Preventive measures include wearing protective clothing, using insect repellent and removing standing water from property, where mosquitoes breed.