A norovirus case at Auckland's Baradene College has prompted a warning to parents, but the school says no further cases have been reported.

The Catholic girl's school in Remuera wrote to parents yesterday after a Year 7 student was confirmed to have fallen ill with the highly contagious stomach bug.

It asked parents to keep their daughters home and seek medical advice from a GP if they had any symptoms of the virus.

Baradene principal Sandy Pasley said the school nurse had sent home two or three girls with stomach upsets each day last week.

However, there had only been one confirmed norovirus case, and the number of students with stomach upsets had settled down this week, with nobody sent home yesterday.

"It's not at a catastrophic stage where it's spreading like wildfire," Ms Pasley said.

"It's a matter of getting onto it quickly and trying to get the information out there to parents and to students."

Ms Pasley said students had been spoken to about washing their hands carefully, as well as not sharing food or drinks with other girls.

Norovirus can spread quickly with symptoms including nausea, vomiting, stomach cramps, violent flu-like symptoms and lack of appetite.

- APNZ