Chicago School Shutters After 800 Kids, 50 Staff Ill With Suspected Norovirus The St. Charles East High School in Chicago shut down for a second day Wednesday

 -- A Chicago high school shut down for a second day Wednesday after a suspected outbreak of norovirus sickened some 800 students and 50 staff, school officials said.

"While a clinical determination has yet to be made about the stomach virus that is going around, the symptoms are similar to norovirus, so, we are following the procedures regarding norovirus," St. Charles District 303 said in a statement. "We are now working to assist the Illinois Department of Public Health in their efforts to more clearly identify this virus."

The St. Charles East High School is home to about 2,500 students and 100 staff, many of whom reported telltale signs of the virus, which include diarrhea, throwing up, nausea and stomach pain, according to officials.

Norovirus is the leading cause of illness and outbreaks from contaminated food in the United States, accounting for about half of all all outbreaks of food-related illness, according to the Centers for Disease Control.

The virus sickens some 19 to 21 million Americans annually and contributes to as many as 800 deaths.

The high school decided to shut its doors for a second day in accordance with recommendations from the CDC that people with a suspected norovirus infection be symptom free for 48 hours before returning to normal activities.

Classes at the school are set to resume on Thursday.

Symptoms of a widespread illness started appearing on Saturday night, ABC affiliate WLS-TV reported, when a boys' basketball game was postponed because 10 of the team's 14 players were ill.