CHICAGO (CBS) — The City of Chicago is taking action Tuesday and Wednesday, in hopes of minimizing Chicagoans’ chances of getting the West Nile virus.

Beginning at 8 p.m. Tuesday, the Chicago Department of Public Health will spray in a few South Side neighborhoods. They will tackle the 7th Ward – which includes much of the South Chicago, Calumet Heights and The Bush neighborhoods – and the 10th Ward – which includes much of the Southeast Side south of 83rd Street, from the Lake Calumet to the Illinois-Indiana state line.

On Wednesday, city crews will move to the Northwest Side. They will spray in the 36th Ward – which includes the Schorsch Village, Irving Woods, Belmont Heights, Montclare and Galewood neighborhoods – and the 41st Ward – which includes the Edgebrook, Wildwood, Edison Park and Norwood Park neighborhoods, and O’Hare International Airport.

The crews will be laying down a chemical called Zenivex, a substance approved by the U.S. Environmental Protection Agency to exterminate the northern house mosquito, which can carry West Nile.

For weeks now, scientists have been noticing that mosquitoes infected with the virus have been turning up in their traps, often bred in standing water.

The first two human cases in the Chicago area were reported last week.

Most people who contract West Nile virus don’t suffer any symptoms, but generally, people over the age of 50 are more susceptible to the flulike symptoms that can accompany the virus.

In most instances, mild cases of West Nile can cause stomach pain, diarrhea, fever, headaches, swollen glands and sore throats. In addition to older adults, children are also at high risk.

Although the overwhelming number of West Nile cases are mild, and don’t require going to the hospital, the worst year in Illinois was 2002, when there were 884 cases across the state, and 67 deaths – 42 of them in Cook County.

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