PYEONGCHANG-Pyeongchang olympic organisers were scrambling Wednesday to prevent an outbreak of the highly contagious norovirus spreading to athletes after the number of cases nearly tripled overnight.

No athletes are among the 86 confirmed cases so far and officials at the Winter Games say they are doing everything they can to ensure it stays that way, two days before the Olympics open. Any illness spreading to the competitors -- particularly one of the star names -- would be a major embarrassment to hosts South Korea.

Underlining growing concerns about the spread of the stomach bug, which causes diarrhoea and vomiting, the Korean Centre for Disease Control and Prevention held a press conference to outline what steps it was taking.

"As of February 6 we had 32 cases, but today... we have an additional confirmed 54 cases so in total we have 86 cases of norovirus," said the centre's director Kim Hyun-Jun. Among those were three from food preparation staff in the media village. The virus can be spread through food or water contamination.

Hundreds of soldiers have been drafted in to guard olympic venues after 1,200 security staff were withdrawn and quarantined earlier this week over the outbreak. The security guards, all employees of a security company, were staying together at a youth training centre in Pyeongchang -- separate from the main olympic sites -- believed to be epicentre of the virus.

"There's no confirmed cases (among athletes) and that's the most important thing here, that when the athletes come to Korea they demonstrate their performance after a few years of training," said Kim. "In order to prevent any kind of accident that will prevent them from competing well and enjoying the Games we're doing our best."

Quarantining patients for 48-72 hours and rushing out hand sanitisers to venues are among the urgent measures officials have taken and American biathlon Lowell Bailey admitted that he had concerns. "I think as endurance athletes we're constantly trying to find the balance between mild paranoia and being at ease with the situation," he said.

"Sickness happens, people get sick and the key is staying focused and doing what we can. Often it's just the simplest things that you can think of -- washing your hands, getting enough sleep and not doing stupid things."