Nasty norovirus hits the digestive system hard
Sarah Hamilton, her husband, and their two small children have been sick so often this winter she and her spouse have joked that they’d better buy cancellation insurance for their next holiday. The most recent bout of illness involved vomiting all ’round and a lot of time on the couch. The Burnaby family is hardly alone.
“It seems like everyone I talk to this year has had it,” Hamilton says in a phone interview. “You go to Facebook and everyone’s status is either ”˜sick’ or ”˜recovering’.”
Those episodes of stomach upset—often erroneously referred to as “stomach flu”—are most likely caused by a norovirus, according to Eleni Galanis of the B.C. Centre for Disease Control. The physician epidemiologist (who, along with her young daughter, experienced the illness herself recently) confirms that the gastrointestinal virus is hitting Metro Vancouver hard this season.
“We’ve had a more severe year than usual,” Galanis says on the line from her office. “This virus goes in two- to three-year cycles, and this is a peak year. It’s extremely contagious.”
Norwalk, which has made headlines throughout North America in recent years for striking large groups of people in settings ranging from luxury cruises to nursing homes and hospitals, is one type of norovirus. The group of viruses gets its name from Norwalk, Ohio, where an outbreak of vomiting and diarrhea hit an elementary school in 1968.
In 2009, the most recent year for which statistics are available, 80 outbreaks of gastroenteritis (irritation or inflammation of the stomach and intestines) were reported in B.C., according to the BCCDC. (An “outbreak” is defined as two or more epidemiologically linked cases occurring in a specific period.) Eighty-five percent of those were caused by a virus. Eighty-nine percent occurred in residential institutional facilities, and five spread through food-service establishments.
The actual number of cases of norovirus that occur in any given year isn’t known, because many go unreported or undiagnosed.
Norovirus infections typically occur between late November and March or April, although they can happen at any time of the year.
The term “stomach flu” gets used frequently, but norovirus is not to be confused with influenza, Galanis points out. The flu is a respiratory illness that can cause cough, sore throat, fever, muscle aches, fatigue, malaise, and headaches and last for a week or longer.
The norovirus, meanwhile, targets the digestive system. Besides vomiting or diarrhea, symptoms can include nausea, cramping, chills, and fever.
Signs usually start 24 to 48 hours after exposure and last 12 to 36 hours. Besides being spread from person to person through what’s known as the “fecal-oral route”, norovirus can be transmitted via food, water, or ice that’s been handled by someone who’s sick. It can also be spread through the air.
“You can aspirate it,” Galanis says. “You don’t need a lot of the virus to get sick.
“People are usually most contagious when they have symptoms,” she adds. “However, the virus can be shed in stool for several days after a person starts feeling better.”
Anyone who has been sick with norovirus should stay home until at least 48 hours after symptoms have stopped.
That’s easier said than done, though, as Hamilton can attest.
“You’ve got to go to work, so you’ve got to send the kids to daycare,” she says.
And so the cycle continues.
Stomach upset can also be caused by parasites such as giardia, which is mostly spread through contaminated water, and bacteria like salmonella and Escherichia coli. Those infections cause more severe symptoms and can be serious in young children, older people, and those with compromised immune systems. Some food poisonings also result in the sudden onset of symptoms.
“You’re usually quite sick within hours of eating,” Galanis says. “Diarrhea is of shorter duration [than what occurs with norovirus]. You’re usually sick for a matter of hours rather than a day or two.”¦People tend to want to blame it [their illness] on the last thing they ate.”
Another clue that food poisoning has occurred is that several people will get sick at the exact same time. With norovirus, by contrast, one person in a household or institution will be ill, then others in the same environment will become sick a day or two later.
The good news is that noroviruses are “self-limiting”: “It goes away by itself,” Galanis says. Complications are rare, but the viruses can cause severe dehydration in the elderly and the very young.
The best way to avoid catching a gastrointestinal bug is to be diligent about thorough hand-washing, including before and after preparing food. That means scrubbing with soap and water for at least 20 seconds. Try singing “Happy Birthday” or some other tune to yourself to ensure you’re washing long enough. Surfaces (including floors) should be scoured regularly too, especially if someone in your house has been sick. In that case, the BCCDC suggests using a diluted bleach solution (four teaspoons of bleach to one litre of water). Clothes and bedding should be washed in hot water.
“Norovirus is a hardy organism,” Galanis says. “It can survive in an environment for many days.”