Eighteen players, including Vedran Corluka and Wilson Palacios have been affected by the bug which causes sickness and diarrhoea.
"We've closed the training ground. It's off limits. We're just going to train there and that's it," manager Harry Redknapp has said.
"We had a few down with it the other day. Corluka had the virus and Palacios was not feeling great with it either..
"It hasn't disrupted us, we are still training as normal and hopefully no-one else gets it but there have been so many other people who have gone down with it, including a few of the press boys who came over on Tuesday, it is certainly spreading."
A statement from the club read:
"A number of (academy) scholars and several first-team players have reported feeling unwell and, as a precaution, are being kept away from the training ground for a period of 48 hours in order to avoid the risk of spread.
"As an additional precaution, the club has undertaken a comprehensive deep clean of the entire training ground's facilities while all administrative and academy staff have been instructed to work from home until Monday."