Dulaney and Hereford high schools in Baltimore County have been bitten by the flu bug, or some bug causing flu-like symptoms that have sent hundreds of students home to bed.
"It seems to have hit our two schools," said Ray Gross, principal of Hereford High.
"Monday we were fine but Tuesday, it [absenteeism] jumped out of sight. It just seemed to work its way up the valley," he said.
Tuesday, Wednesday and yesterday, about 95 of Hereford's 795 students were out sick, Mr. Gross said. On an average day about 32 students are absent, he said.
At Dulaney High near Timonium, about 350 of the 1,450 students were out sick Monday and Tuesday, said Richard E. Bavaria, spokesman for the county school system.
By Wednesday and yesterday the number of students absent had fallen to 270, a substantial decline but still more than triple the average daily absenteeism of about 87.
"The nurse has been very busy seeing kids with flu symptoms," Mr. Bavaria said.
Students at other county schools have had flu symptoms, "although we don't have what you consider a real wave of it," said Karen Stott, a Baltimore County Health Department spokeswoman.
On Monday, six of the county's 147 public schools reported absenteeism of more than 10 percent. On Tuesday, the number had fallen to four schools, and on Wednesday, the most recent day for which figures were available, only one school reported more than 10 percent of its students were absent.
Mrs. Stott said people with flu symptoms -- aches, coughs, sore throat and fever -- should rest and avoid crowded places because the virus is carried through the air.
In neighboring Baltimore, a public school spokeswoman said absences because of flu have not been abnormally high recently.
Baltimore County's Sparks Elementary appears to be among schools where few students have been felled by the flu.
Attendance has been normal all week.
Asked if his school had been hit, Principal R. Wayne Law responded, "just the principal."