Norovirus has hit the PyeongChang Winter Olympics, just days before the 2018 Games begin. Dozens of security guards have been infected, and hundreds more are being checked for signs of the contagious virus. Here’s what you need to know about norovirus and the Winter Olympics:

How many people have norovrius at the PyeongChang Olympics?

Thirty-two security guards who are part of a private security group at the PyeongChang Olympics are infected with the norovirus as of Tuesday, according to the PyeongChang Organizing Committee for the Olympic Games (POCOG). Lab tests confirmed the infections and all are currently under quarantine.

More than 1,000 people living in the same youth center facility in Jinbu, part of PyeongChang County, are being investigated for signs of the virus. Eleven of the people affected did not live in the youth center and three are non-Koreans.

In a statement issued on Tuesday, POCOG said that the Korea Ministry of Food and Drug Safety and the Ministry of Environment have conducted tests of the water system used for cooking food in the facility but have not found signs of the virus.

What is norovirus and how does it spread?

Norovirus is extremely contagious and has been responsible for numerous outbreaks on cruise ships. The virus can spread from contaminated water or food or by touching contaminated surfaces. The virus causes inflammation in the stomach and digestive system, which leads to severe diarrhea, nausea and vomiting. Foods most often contaminated with the virus include oysters and fresh fruits and vegetables that aren’t washed or cooked before they are eaten.

Norovirus infections spread most commonly where there are lots of people in a confined area, such as cruise ships, day care centers, nursing homes and residential facilities at massive events such as the Olympics. Nearly 3,000 athletes from 92 countries, an estimated 80,000 tourists daily, 17,000 volunteers and thousands of journalists from around the world descending into tight quarters in PyeongChang create the perfect conditions for viruses to spread.

How is norovirus treated?

Because it is caused by a virus, norovirus infections cannot be treated with antibiotics. There are no specific antiviral medications for treating symptoms. The main treatment is to ensure infected people affected drink plenty of water to prevent dehydration from the vomiting and diarrhea. For the most part, it’s a matter of riding out the unpleasant symptoms until the body battles back the bug.

How are Olympics officials responding to the norovirus outbreak?

In the meantime, Olympic organizers are not taking any changes. At the main dining hall in the media village in Gangneung, where most of the skating, speed skating, hockey and curling events will be held, volunteers politely asked journalists to spray and rub their hands with sanitizer as they entered the cafeteria. Servers wear masks and spray tables with sanitizer after every diner leaves. The Korean Center for Disease Control also recommends boiling water before drinking it and is advising anyone with diarrhea not to cook for others.

The U.S. Centers for Disease Control and Prevention, as well as its Korean counterpart, says washing hands thoroughly and frequently is the best way to prevent getting the infection and spreading it if you are sick. Disinfecting potentially contaminated surfaces is also important, and cooking raw foods like seafood as well as washing fresh produce and vegetables before eating them is critical to protect people from getting sick in the first place.

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