AN INFLUX OF mosquitoes caused by sporadic weather conditions has led city officials to begin targeting mosquito breeding grounds to protect Chicagoans from possible West Nile virus infections. 

The Chicago Department of Public Health began spraying portions of the city’s Northwest Side on Aug. 20, according to a statement from the city. 

The Illinois Department of Public Health announced Aug. 19 that the first human case of West Nile virus in Illinois this year had been diagnosed. The patient is recovering in her West Ridge home, according to the city’s statement. 

“When our mosquito traps indicate that the West Nile virus may threaten human health in a community, we take decisive action,” said Chicago Department of Public Health Commissioner, Bechara Choucair in a statement. 

Zenivex, an insecticide used to control disease-carrying mosquitoes, was sprayed in portions of the 36th, 38th and 41st Wards on Aug. 20 and Aug. 27 in the 29th, 30th, 31st, 36th and 37th wards, according to statement issued by the city’s public health department. 

Conditions in Chicago’s Southwest and Northwest sides are usually optimal for breeding mosquitoes, according to Cort Lohff, medical director of Environmental Health for the Chicago Department of Public Health. 

In addition to spraying insecticide from trucks into residential areas, the city also distributes and monitors larvicide in catch basins around the city, which prevent mosquito larvae from maturing into adults, Lohff said. It’s important for Chicagoans to protect themselves from mosquitoes, he said. 

“In some ways, it’s most important for people to take measures themselves from ever being [bitten] by mosquitoes,” Lohff said. 

Experts suggest there are more effective methods to control mosquitoes in urban areas than spraying insecticides from trucks. While controlling mosquito larvae is effective, treating storm drains and clearing mosquitoes from sewers also works well for urban areas, according to Joseph Conlon, technical advisor to the American Mosquito Control Association. 

“Urban areas are problematic, primarily due to the heat being given off by the buildings and the types of drafts you have,” Conlon said. “In the case of West Nile virus, they’ve also found that the mosquitoes that transmit West Nile virus tend to hang out in these drains themselves and in the sewers.”

Residents of the 38th Ward were concerned about the West Nile virus following a storm that brought standing water to the local cemetery, said Tim Cullerton, alderman of the 38th Ward. 

While the city sprays insecticides and monitor catch basins, residents should call 311 if they see an inordinate number of dead birds or any standing water, Cullerton said. 

“During the last rain storm in the western part of the ward, we had a lot of flooding earlier in the summer right around mosquito season in the cemeteries,” Cullerton said. “It takes a couple of weeks to dissipate the water completely, which is enough time to breed the mosquitoes.”

To stop mosquitoes from breeding near homes, Conlon said eliminating standing water in places such as ditches and drains because they require still water to breed and lay their eggs. 

People can also monitor ventilation systems, windows and door screens to prevent mosquitoes from coming inside, Conlon said. Wearing long, loose clothing and Environmental Protection Agency-approved mosquito repellent helps keep mosquitoes from biting while outdoors, he said. 

“Wear clothing that’s loose fitting because mosquitoes can and will bite through tight clothing,” Conlon said. “Particularly in Illinois, repellency and effectiveness of repellency could be a matter of life and death.”