More than 400 students in East China's Zhejiang province have been infected with norovirus, a common cause of viral gastroenteritis, local authorities said Wednesday.
The students from several schools in Haining City and Haiyan County, including kindergartens and middle schools, are receiving treatment in local hospitals, according to the municipal government of Jiaxing City, which administers the two places.
No deaths have been reported so far, according to the government.
Classes will be suspended on Thursday and Friday but are expected to resume on Monday.
The outbreak began on February 11 in Haining and February 13 in Haiyan.
It is suspected that the outbreak was caused by barrelled water. All the affected schools have been using barrelled water with the same brand, said Yang Jing, head of the provincial health and family planning commission.
A further epidemiological investigation is under way, said Yang.
"Norovirus infection is characterized by vomiting and diarrhea. In general it will be self-cured within three to five days," said Chai Chengliang, a health expert with the provincial disease control and prevention center.
The virus can easily break out in densely-populated areas and is transmitted through the digestive system as well as the respiratory system, he said.
Governments have ordered all the schools to disinfect canteens, classrooms, dormitories and toilets.