Some classes at Modbury West Primary School, which has 420 enrolments, had less than 10 students in attendance Friday.

Principal Deb Hancock told Advertiser.com.au the school sent a text message to parents on Thursday informing them many children had been unwell.

The text message also asked parents to keep children at home if they felt sick.

Ms Hancock said a dozen students were sent home on Thursday on the same day there were 80 children absent from class, after they showed gastro symptoms.