Parents of students at a Greenwich middle school say they are keeping their kids home to make sure they don't get swine flu.

Out of almost 500 students, Western Middle School officials say 166 were out of class Thursday and more than 200 students were not in class Friday.

A nature trip for sixth-grade students ended early this week after 19 students had fevers and 36 complained of headaches. Officials confirmed Thursday that one of the students on the trip has swine flu.

The district says out of the sixth-graders that have been tested, just over a dozen were positive for some type of influenza. However, the district reminded many that although those tests were positive, it does not mean they have swine flu.

School Superintendent Betty Sternberg says all schools in Greenwich will stay open and that the town's health department is closely monitoring the situation and following CDC guidelines.

The CDC says school closure is not advised unless there are enough students or faculty absent that it interferes with the school's ability to function.

On Friday, the district defended its decision to keep the school open, saying it followed the recommendation of the town's health experts.