The virus has found a home at the Olympics and is spreading rapidly. The PyeongChang Organizing Committee had confirmed 128 cases by Thursday. Competitors and attendees alike are being warned to be extra careful about proper hand hygiene in hopes of stemming the tide of infections.
According to the committee, on Sunday, private-security personnel staying at the Horeb Youth Center reported symptoms such as diarrhea, stomach pain and headaches. Provincial and federal officials launched an immediate investigation into the 1,023 youth center residents.
Water and food are being tested to trace the route of transmission, but according to the Ministry of Food and Drug Safety and the Ministry of Environment, all results have been negative.
The illness has caused a shortage of healthy security workers, so 900 military personnel have been deployed to take over the effort across 20 venues until the affected staff are able to return to duty.
What is norovirus?
Norovirus is a group of related viruses in the Caliciviridae family. It's spread through the ingestion of infectious virions, which grow in the small intestine before being expelled in feces.
Dr. Sarah Hochman, associate hospital epidemiologist at NYU Langone Health, says "norovirus is a viral infection that is either person-to-person or spread through eating contaminated food, and it causes really an acute onset of vomiting and diarrhea that lasts anywhere from one to three days."
Norovirus can be found in an infected person's feces even before they start feeling sick and two weeks or more after they feel better.
Anyone can get norovirus and can be infected many times over the course of their life. "A reason for this is that there are many different types of noroviruses," the US Centers for Disease Control and Prevention says
. "Being infected with one type of norovirus may not protect you against other types."
You are most contagious when you are feeling sick and during the first few days after you recover from the illness, according to the CDC.
The virus and food
Infection usually occurs when someone eats food or drinks liquids that have been contaminated, touches surfaces or objects that are contaminated and then puts their hands in their mouth, or has contact with someone who has been infected, such as by sharing food.
Most norovirus outbreaks happen in food service settings, the CDC says. Food workers who touch foods with their bare hands before serving are frequently the source. Any food served raw or handled after being cooked -- such as oysters or fruits and vegetables -- can become contaminated.
"If you have fresh fruits or vegetables that may have been grown in an area that got contaminated either by sewage or water that had norovirus in it, that is another way of it entering the food we eat," said Hochman.
Symptoms and prevention
According to the CDC, norovirus causes inflammation of the stomach, the intestines or both. A person usually develops symptoms 12 to 48 hours after being exposed.
"The main symptoms are diarrhea and throwing up. Some people also have fevers and muscle aches, but the real hallmark of this infection is the pretty abrupt onset of these symptoms," Hochman said.
Other symptoms include stomach pain, fever, headaches or body aches.
As for preventing infection, "hand-washing is the most important thing, that is using soap and water," Hochman said. "I know a lot of us use the alcohol-based hand rubs ... but the alcohol-based hand rubs are not effective in killing the viral particles." She also recommends using bleach to clean surfaces.
Another frequent prevention strategy is quarantine. Hochman suggests isolating people who could have been exposed to norovirus because the symptoms begin relatively abruptly after exposure.
"It is anywhere from 12 to 48 hours, so as long as those people who maybe shared a room or bathroom with someone diagnosed with norovirus can be quarantined for 48 hours and watched to make sure that they don't develop any symptoms, that is a way to try and prevent the spread to other people," she said.
The CDC recommends practicing proper hand hygiene, washing fruits and vegetables and cooking food thoroughly before eating, not preparing food for others when you feel sick, and cleaning and disinfecting contaminated surfaces.
"Norovirus is tricky in that it is highly, highly infectious. It only takes a few viral particles to cause infection, and the virus itself can remain infectious on surfaces for fairly long periods of time," Hochman said.
There is no specific medicine or vaccine to treat norovirus, but most people recover fully without treatment.
Risk to athletes
"The biggest risk is dehydration, which is more important for athletes than anyone else, especially if they are expected to perform within the next one to two weeks," Hochman said.
Dehydration is linked to norovirus because it's hard for those infected to take in as much fluid as they are losing to vomiting and diarrhea. People suffering dehydration may not urinate as much, may feel dizzy and may have a dry mouth or throat.
In order to prevent dehydration, the CDC suggests drinking plenty of fluids, such as water, sports drinks or oral rehydration fluids.
According to Hochman, recovery time depends on the severity of the infection. Even after the vomiting and diarrhea subside, some residual weakness may take another three to five days to recover -- also not ideal for athletes planning on competing.