The state health department closed a private school in Kochi on Monday after two students tested positive for norovirus and 15 others showed symptoms of the highly infectious viral disease.

All steps were being taken to localise the infections and contain it, state health minister Veena George said. The infected children were in the age group of 5 to 10 years; some parents also exhibited symptoms. Samples from the children were tested in the regional virology lab in Alappuzha after many of them started vomiting and suffered from diarrhoea.

“We have started a full-fledged campaign to arrest its spread. All water bodies will be checked and super chlorination has also begun. We have also isolated infected ones and opened isolation wards,” Ernakulam district medical officer V Jayashree said.

Local residents have been advised to maintain strict hygiene, boil water and cook shell fish and other items in high temperature.

Norovirus spreads through contaminated water, food and through close contact with an infected person, experts said. It’s main symptoms are diarrhoea, vomiting and stomach pain. It is a treatable disease but highly contagious.

“It is a treatable virus that mainly affects children. Symptomatic treatment is needed and many patients fast become dehydrated,” said a doctor of Alappuzha medical college hospital, who declined to be named.

Last year, a norovirus outbreak was reported from a men’s hostel in Alappuzha.