GUANGZHOU, Dec. 26-- A total of 104 students in a primary school in south China's Guangdong Province have fallen ill with norovirus, local authorities confirmed on Friday.

Grade one to three students of Qiming Primary School in Jiangmen city started feeling unwell about 4 p.m. Thursday, said Jiangmen city press office.

They were treated in local hospitals.

By Friday noon, all but 21 of them had been discharged. This is the seventh outbreak of norovirus in Jiangmen this year.

Symptoms of the highly-contagious stomach virus include vomiting, diarrhea, fever and body aches. Usually patients recover within three days.

The local disease control and prevention center warned people that during the cold season, they should wash their hands frequently and carefully, and say no to raw or cold food.