Classes were canceled at St. Charles East High School for Tuesday and all of District 303's 17 schools were being cleaned with bleach Monday evening after a widespread stomach virus caused hundreds of absences at the high school Monday, district officials said.
About 800 of St. Charles East's 2,000 students missed class Monday. The majority of those reported symptoms of a stomach virus -- possibly norovirus, said Jim Blaney, District 303's director of school and community relations.
"Indications point that way (to norovirus), but we don't have definitive answers from people qualified to make that determination," Blaney said.
Regardless, all of the district's 17 school buildings were being cleaned thoroughly with bleach Monday night -- a recommendation by the CDC as an effective way to kill norovirus, among other viruses, Blaney said.
District officials first became aware of the illness on Saturday when 10 of the 14 East varsity boys basketball players became sick overnight. Both the varsity boys and girls games against St. Charles North were canceled, as a result.
"We had one kid who was sick last night," Saints boys' coach Patrick Woods told the Daily Herald on Saturday. "Today (Saturday), 10 of the 14 guys on the team are sick."
As other coaches began to report widespread illness, district officials began to wonder if the issue was limited to athletes or the entire student population, Blaney said. An email went out to parents via the parent notification system asking if their children were sick, and if so, with what symptoms.
"That gave us a decent amount of info that many students were sick," he said.
The building was deep cleaned over the weekend, and students who did attend Monday were released at 2 p.m. for further cleaning. Another mass email went out to parents Monday evening asking them to respond if their child was healthy and would be attending class Tuesday. Feedback from that led to the cancellation of classes, Blaney said.
"One of the key components was asking parents and students to respond to us and give us some information," he said. "The parents have been fabulous in doing so and helped us out a lot -- enough that we felt comfortable making some decisions based on that information."
Students will not return to class at St. Charles East until Wednesday at the earliest. Teachers will report to St. Charles East on Tuesday morning and phone the parents of students in their second-hour classes to gauge the health of students, Blaney said, before district officials will make any decisions about when school will resume.
No formal diagnosis has been given for the outbreak, officials said.
"I am not aware of any parents saying that they took them to the doctor, and they were diagnosed 'this,'" Blaney said. "To say what it is, is speculation."
However, after consulting with the CDC, district officials changed the type of cleaning solution used throughout all 17 buildings to bleach.
Highly contagious, norovirus is most often characterized by diarrhea, vomiting, nausea and stomach pain, according to the CDC. Symptoms usually appear 12 to 48 hours after exposure and typically subside within one to three days. It's common in closed areas like nursing homes, cruise ships, and schools, the CDC website says.
Other schools within the district have not reported widespread illness, Blaney said.
"As of today, there wasn't an indication that anything was out of the norm," he said. "We're keeping a close eye on the absence numbers at our other schools. That's something we watch anyway, but in times like this we keep an extra close eye on it."
• Daily Herald correspondent Craig Brueske contributed to this report.