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The International Olympic Committee (IOC) has a sticky mess to tackle with an outbreak of norovirus right before the Winter Olympics opens.

The IOC said it was isolating 1,200 people handling security for the PyeongChang Olympics and distributing leaflets about preventing infection after 41 security guards were hospitalized with vomiting. On Friday, officials said 86 people were sick, including food preparation staff.

South Korea has moved military troops in to handle security in the interim.

Any large gatherings of people — and the Olympics are a fairly good example of a large gathering — are perfect for the spread of the stomach-churning virus.

A close-up of a norovirus that is causing food poisoning. CDC

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The nasty stomach bug causes vomiting, cramps and diarrhea. It can and does infect hundreds of passengers on cruise ships, people who share a restaurant table or those who eat food prepared by someone sick with norovirus.

It sticks to silverware and counters, can spread in the air when someone vomits and survives being dried out for weeks.

Related: Why washing your hands isn't enough with norovirus

Norovirus, also called stomach flu and winter vomiting virus, sickens 21 million people in the U.S. each year. It kills up to 800 people a year in the U.S. alone and puts another 70,000 into the hospital. There’s no cure — treatment involves supporting people to make sure they don’t suffer dehydration. And there’s no vaccine to protect against infection.

It doesn’t take much to make someone sick.

“The virus can easily contaminate food because it is very tiny and infective. It only takes a very small amount of virus particles (as few as 18) to make someone sick,” the U.S. Centers for Disease Control and Prevention advises.

Many viruses are easy to kill, but not norovirus. It is surrounded by a case called a capsid, which makes it hard to destroy. Alcohol-based hand sanitizers are considered ineffective but a good hand scrubbing can wash the virus away.

Related: Grocery bag spread norovirus

Regular cleaner won’t get the virus off surfaces. The CDC recommends using bleach, including chlorine bleach or hydrogen peroxide.

Norovirus is spread fecally — in the poop — and that means it can get into laundry. Studies show that fecal matter spreads even in ordinary laundry, so if someone is sick, it’s important to use very hot water and bleach to destroy virus that could be on any clothing, sheets or towels.