What is norovirus? 2018 Winter Olympics plagued by vomit-inducing bug

Officials at the 2018 Winter Olympics are scrambling to contain the outbreak of a vomit-inducing, diarrhea-causing, extremely contagious stomach bug known as norovirus.

There were more than 200 confirmed cases of the norovirus in South Korea as of Feb. 16, according to Reuters. The virus has infected at least two athletes at this year's Olympics.

Swiss freestyle skiers Fabian Boesch and his teammate, who has not yet been identified, are the first athletes to catch the virus, the Swiss Olympic team confirmed to Reuters.

“Everyone else is safe. We did everything we could. We took them away from the rest of the team and now they have to recover,” a spokesperson told the news agency.

Switzerland's Fabian Boesch takes a picture during the men's freestyle skiing slopestyle qualification round at the 2014 Sochi Winter Olympic Games in Rosa Khutor February 13, 2014. REUTERS/Mike Blake (RUSSIA  - Tags: SPORT SKIING OLYMPICS)   - LR2EA2D0P5EY0

Switzerland's Fabian Boesch takes a picture during the men's freestyle skiing slopestyle qualification round at the 2014 Sochi Winter Olympic Games in Rosa Khutor February 13, 2014.  (REUTERS/Mike Blake)

At a news conference, the International Olympic Committee said the two athletes are “unwell” but that there was still hope for them to compete, according to Reuters.

The bug began spreading on Feb. 3 among a group of security guards staying at the youth training center in Pyeongchang. Nervous organizers quarantined at least 1,200 Olympics staffers as a precaution and roughly 900 military personnel were deployed to help with the security shortage.

In light of the norovirus, here’s what you need to know.

What is the norovirus?

The norovirus is also referred to as the “winter vomiting bug," Lee-Ann Jaykus, the scientific director for NoroCORE, a food safety initiative that’s funded through a $25 million grant from the USDA, told Fox News.

The virus is not uncommon, as roughly 21 million Americans get the virus each year, according to the CDC.

The norovirus enters the body through the mouth, reaches a person's gastrointestinal tract and inflames the stomach or intestines, or both. As a result, it causes nausea, stomach pain, vomiting and diarrhea, which leads to dehydration. It can also cause fever, headaches and body aches. 

While the symptoms can be severe, most people recover within days.

How does it spread?

The norovirus, which has different strains, can spread easily —especially in closed spaces, Jaykus said.

A common way the virus is transmitted is through close contact with an infected person. This is either directly or indirectly; such as sharing a bathroom, a dorm room or another communal space. Cruise ships, schools and nursing homes “are the most commonly reported settings for norovirus outbreaks,” according to the CDC.

More specifically, however, the virus spreads through fecal matter and vomit.

When an infected person vomits or defecates, “massive amounts [of the virus] are excreted,” Jaykus explained. “There are millions to billions of particles in one just one gram.” 

“It only takes a few virus particles to make people sick,” she added.

The virus also spreads through food and contaminated water.

Food handlers who are sick and don’t practice adequate hygiene can easily infect other people. Infected water can also spread the illness, though this more commonly occurs in developing countries, Jaykus noted.

How do you prevent it?

Unlike the flu and other illnesses, there is no vaccine to prevent norovirus.

Keeping your hands washed and thoroughly cleaning contaminated surfaces is key to prevent the spread of infection.

“Hand washing is hugely important. In fact, it’s the single most important thing for people attending Olympics."

- Lee-Ann Jaykus

“Hand washing is hugely important,” Jaykus said. “In fact, it’s the single most important thing for people attending Olympics,” she said.

The norovirus is extremely hard to kill, Jaykus warned. Inactivating the virus requires a high concentration of bleach. And while it’s easy enough to clean countertops and other similar surfaces with bleach, the same can’t be said for carpet and furniture. Alcohol isn’t strong enough to entirely kill the virus either, Jaykus added.

“The norovirus can be spread for weeks,” said Jaykus, who added that quarantining infected people can also be useful in preventing the spread of norovirus.

How did the norovirus spread at the Winter Olympics?

The short answer: no one is sure.

Health officials in South Korea said that a preliminary five-day survey of water for cooking and drinking has come up negative for norovirus. Restaurants and all food facilities linked to the Olympics will also be inspected.

“This is really scary for the athletes — if you have norovirus you really are incapacitated,” said Jaykus.

The Associated Press contributed to this report. 

Madeline Farber is a Reporter for Fox News. You can follow her on Twitter @MaddieFarberUDK.