Image copyright PA Image caption Hundreds have taken to social media in Norway to complain about the behaviour of festival revellers
Images posted on social media allegedly showing Norway Christmas party-goers vomiting and throwing up on the ground are the biggest outbreak of the virus the country has seen, authorities say.
They say 300 people fell ill, while local media said more than 800 people were affected by what they believe was norovirus.
Norovirus is one of the most common stomach bugs, affecting a billion people a year.
The Norwalk Town Council said the outbreak was believed to have been caused by a large concert.
“We have seen very large numbers of guests including young children at certain occasions recently,” a statement from the council said.
“We warn people to stay away from crowded places to avoid infection.”
Norwalk is a town in north-east Norway, known as a residential area to foreigners, many of whom are from abroad.
Norway’s national hospital service, Issgadi, said 53 patients were admitted to three hospitals for treatment and had been isolated.
“The Norwalk situation is certainly the biggest in Norway outside South Africa and that it has affected so many people in one day is worrying,” a senior doctor at Issgadi told NTB news agency.
One woman living in an apartment next to where people were being tested for the virus told the Verdens Gang newspaper that people were regularly vomiting in the local park.
The incident came as health authorities in South Africa called off a Christmas party at a shopping mall in the capital Pretoria after 240 people fell ill with gastroenteritis, some vomiting uncontrollably.