“An epidemiological survey is underway to understand the route of transmission,” the PyeongChang organizing committee said in a statement Tuesday.
The outbreak, revealed just three days before Friday’s Opening Ceremonies, is particularly unwelcome given the security concerns surrounding these Games, which are taking place just 50 miles from the border with North Korea.
Security has been tightened perceptibly, with travelers passing through train stations having to go through metal detectors. Soldiers in fatigues were manning entry points to skiing and snowboarding venues Tuesday.
The security guards who came down with the virus were all staying at a youth center in the PyeongChang area, and reported experiencing headaches, stomach pain and diarrhea. They were treated and quarantined.
More than 900 military personnel have been deployed to take over security at 20 Olympic venues until all the affected workers are able to return to duty, the organizing committee said in a statement.
Provincial health authorities and the Korea Center for Disease Control and Prevention are investigating the cause of the virus. The youth center is located in the mountains, so health authorities are focusing on tap water, although tests of water used for cooking and general consumption so far have been negative for norovirus. They are also checking food and food preparation.
Authorities also are beefing up hygiene inspections at food facilities across the Olympic venues.
“They’re really making the ultimate possible effort to make sure that everybody is aware [of the virus] and where there are cases, that the right measures are taken,” Christophe Dubi, the Olympic Games executive director for the IOC, told reporters.
Norovirus is highly contagious and commonly spread through contaminated food or water or contaminated surfaces, according to the Mayo Clinic. It also can be spread through close contact with an infected person.
Symptoms usually begin 12 to 48 hours after exposure and last one to three days. There's no specific treatment for norovirus infection, the clinic says on its website.
Norovirus infection occurs most frequently in closed and crowded environments such as hospitals, nursing homes, child care centers, schools and cruise ships.