MERRILL -- Flu symptoms have struck 135 students at Prairie River Middle School, prompting the Merrill Area Public School District to close the school and cancel extracurricular activities and events until Monday.

The district hopes its decision will help those already ill recover in time for school next week and prevent the spread of the influenza virus to healthy students and faculty members, Merrill Superintendent Lisa Snyder said. The middle school, which serves sixth-graders through eighth-graders, has 686 students.

"We saw a trend (of sick students) developing, and we wanted to reduce that," Snyder said.

The school district looks for a few signs before determining whether a student might have the flu. Those symptoms are a fever, stomach and respiratory issues, and a sore throat, she said.

The school closed at 4:30 p.m. Monday, with plans to reopen to teachers and staff members at 7 a.m. today, in an effort to let the germs die on their own. The influenza virus cannot survive on objects and surfaces after eight to 10 hours, said Shelley Hersil, a health officer for the Lincoln County Health Department.

Normally, the school district would have given students about three days off of school, Snyder said. Because there were no classes scheduled Thursday and Friday for a teacher convention, the break will give students nearly a full week to recover or stay healthy.

The key, though, is that all students, sick and healthy, stay home during their time off, Snyder said.

"In some communities, kids (that were off of school because of widespread flu) would go to the mall and hang out," she said. "We really need our parents to partner with us and help us out. Kids need to stay home so the illness doesn't spread to them or from them."

Merrill parent RaDell Jaeger said she will keep her daughter, Randi, 12, who is in sixth grade at Prairie River, at home during that time for everyone's benefit.

"She will not go anywhere," Jaeger said.

She said she's not surprised to see flu symptoms popping up in schools statewide.

"It's everywhere," she said. "The key is to wash your hands, wash your hands and wash your hands."

After-school and evening middle school co-curricular events, including practices and pool activities, are canceled until Monday. The middle school also will remain closed to the public until that time.

The high school and elementary schools within the district will remain open, Snyder said. Students and faculty members will not have to make up the time off, she said.