According to official figures, almost a million people are estimated to have contracted the highly infectious vomiting bug norovirus this winter in the UK.
Health officials believe that around 900,000 people, almost twice the figure reported for this time last year, have caught the virus, which causes severe vomiting for up to five days.
It is feared that the large number of social functions being held in the lead up to Christmas could escalate the problem, threatening a miserable festive period for thousands.
The virus is spread through poor hand hygiene and those who contract it can remain infectious for up to one week after the symptoms have disappeared.
"If you are good at making sure people are hygienic, and making sure that people who have been symptomatic stay away from those at risk of infection, you still can't guarantee that they aren't going to get it," warned John Harris, an expert on norovirus at the Health Protection Agency.
"People needed to consider whether to invite relatives around if there had been norovirus in the house recently. Guests needed to think about whether to go," he added.