Norovirus Stomach Bug On The Uptick: What It Means In Colorado

Ian Krietzberg
·3 min read

COLORADO — The FDA is watching a rise in cases of norovirus, the highly contagious stomach bug that is the leading cause of food-borne illnesses in the United States. This increase in cases has been attributed to the distribution of contaminated oysters to restaurants and retailers across several states including Colorado.

Norovirus is the scientific name for the bouts of vomiting and diarrhea that many times will sicken entire households before running its course. Outbreaks were nearly nonexistent at the height of the COVID-19 pandemic, according to federal health data, and experts believe it’s because Americans largely stayed away from the places where norovirus spreads.

But with the easing of coronavirus restrictions came an uptick in cases of norovirus, an aggressive virus that can easily contaminate food and water.

That’s one conclusion of Dr. Robert Atmar, a professor of medicine and infectious diseases expert at Baylor College of Medicine in Houston, who discussed the increase in norovirus cases with NBC News.

It takes only a few of the billions of microscopic norovirus particles to make a person sick.

Norovirus is spread in a number of ways, including through vomit and feces particles that may remain on a person’s hands or on surfaces during food preparation. It also can come from contaminated water that is used for irrigation of fruit and vegetable crops — or if food, such as oysters, is harvested in contaminated water.

The most recent example of the latter: As of Monday, 91 people had been sickened after eating oysters distributed in at least 13 states, though the U.S. Food and Drug Administration said more states could be affected from further distribution.

The oysters were harvested from a specific bay in British Columbia, the Centers for Disease Control and Prevention said. The majority of those sickened after eating the oysters were in Canada, where at least 279 illnesses have been reported, but also in mainly three U.S. states:

But even before the oyster-related outbreaks, norovirus was making a comeback. Data collected by the CDC's National Outbreak Reporting System shows that 448 norovirus outbreaks were reported from August 2021 to March 2022, compared with 78 outbreaks during the same period the previous year.

The number of outbreaks has increased from 10 or fewer per week from August until mid-November, when they rose to near 30 before falling again, and then spiked to around 60 outbreaks in February.

State health departments in Massachusetts, Michigan, Minnesota, Nebraska, New Mexico, Ohio, Oregon, South Carolina, Tennessee, Virginia, Wisconsin and Wyoming reported norovirus cases during the most recent seven-month period.

Agencies aren’t required to participate in the norovirus surveillance system, which the CDC says makes it impossible to estimate the true number of norovirus cases. Many cases don’t require a visit to the doctor’s office, and most hospitals and other health care providers don’t test for it, the agency says.

Symptoms such as vomiting, diarrhea, nausea and stomach cramps usually appear from 24 to 48 hours after exposure. People are contagious from the point they start feeling ill and for up to two weeks.

The best thing to do is to prevent its spread. Wash your hands the right way, for at least 20 seconds under hot, soapy water, taking care to scrub under nails and between your fingers. Also, clean up food preparation surfaces with diluted bleach.

Quick bouts of gastrointestinal norovirus illnesses are often referred to as the “stomach flu,” though that’s technically incorrect. Influenza is an infection of the respiratory system.

This article originally appeared on the Across Colorado Patch