At Comprehensive Grammar School in Methuen there were as many as 100 students out last week. Central Catholic High School in Lawrence had 200 teenagers absent one day two weeks ago, and in Haverhill about 7 percent of the city's 7,500 students did not go to school on Monday.

Flu-like symptoms are leaving a lot of seats empty in schools throughout the Merrimack Valley. Symptoms include a high fever, cough, sore throat, body aches, and exhaustion.

During the past month, 240 people of all ages went to Lawrence General Hospital for treatment of flu-like symptoms, said registered nurse Kim Downer, manager of emergency services.

Downer said using common sense is the best prevention to catching the flu.

"Being prudent about keeping your distance is specially important if someone is sick and covering your cough," she said.

School officials in area communities are watching the number of students absent from school with the flu or its symptoms. The number in these towns is slightly higher than expected during a regular flu season.

"We're always concerned when students are out," said David DeFillippo, principal at Central Catholic High School in Lawrence. He said school nurse Nancy Walsh provided a daily report on flu-like symptoms and the school tracks it weekly.

"We're doing what we can to help the students and their families, which in turn helps the community," DeFillippo said.

Kathleen DeFillippo, health and nursing services coordinator for Lawrence public schools, said a high fever is a big indication that a child should not be in school, even if it's not flu related.

"We feel we're up to date on what's happening and we're just trying to take care of the kids," she said.

In addition to having hand sanitizers in the offices, classrooms and restrooms, nurses are monitoring student absences.

She said Lawrence schools work closely with the Greater Lawrence Community Health Center. On Wednesdays, nursing professionals have a conference call with representatives from the Department of Public Health in Boston.

The goal is to keep schools open, as recommended by the Department of Public Health.

Methuen School Superintendent Jeanne Whitten said schools would close if there was a large number of teachers and staff sick.

"When we talk with experts in the field they tell us that no matter what you do in terms of cleaning, it's much more important to teach children how to cough," Whitten said.

"It's a tough time in the schools. We're just going to go along, keep tracking the absences and follow the guidelines," Whitten said.

At the beginning of the school year, local departments sent home information on what the H1N1 flu is and preventive measures. In Lawrence schools, there are posters throughout the classrooms on how to wash hands properly as well as cough etiquette. Nurses also talk to students in their classrooms.

Lawrence students who are sent home because they are sick get a letter telling their parents why they were dismissed and what to do.

Central Catholic, with a school population of 1,338 had 200 students out one day two weeks ago. "We never even discussed or entertained the idea of closing," Principal David DeFillippo said.

Then last week, 12 to 14 students were out of school sick and 86 percent of the student population was present.

"It was an unusual week for sure," he said. "It looked like we had a wave because we typically have 2 percent out for various reasons."

Haverhill School Superintendent Raleigh Buchanan said his department is monitoring the flu daily and is in constant communication with the school nurse.

Mary Ellen Daly O'Brien a member of Haverhill's Public Safety Committee, said health officials are no longer testing for the H1N1 flu because of its cost, unless the person needs to be hospitalized.

Daly O'Brien, a School Committee member, had the illness hit her family, including her 16-year-old daughter, Bridget O'Brien, and her older daughter, Julia O'Brien, 24.

"The doctor did not test for the swine flu, but he could tell it was because of her heavy breathing. She sounded like Darth Vader with congestion, aches and a high temperature."