July 12, 2012 (CHICAGO) --
Chicago's Department of Public Health took action Thursday night to try to prevent the West Nile Virus.Crews were spraying insecticide on the far Northwest Side to kill adult mosquitoes that can transmit the disease.
The work is going on in parts of the 36th and 41st Wards in areas where traps have captured mosquitoes carrying the virus.
City officials say the insecticide is not harmful to people or pets.