Norovirus Outbreaks: Doctors' Advice Amid Major Surge in Illness

2 days ago 7

As a severe outbreak of norovirus, also known as the stomach flu, spreads across the United States, doctors have shared advice with Newsweek on what to look out for about the illness.

Why It Matters

The highly contagious illness has reached its highest levels for this time of year in more than a decade, according to the latest data from the U.S. Centers for Disease Control and Prevention (CDC).

The CDC has reported 91 outbreaks during the week of December 5, up from an average of 65 during the same period from 2012 to 2020.

As the illness causes an average of 900 deaths annually, mostly among older adults, along with 109,000 hospitalizations and 19 million to 21 million cases in the U.S. each year, prevention measures can be lifesaving.

What Is Norovirus

Norovirus is the leading cause of foodborne illness in the U.S., responsible for nearly 58 percent of foodborne infections annually.

Dr. William Schaffner, an infectious disease professor at Vanderbilt University School of Medicine in Nashville, Tennessee, told Newsweek in an email on Sunday that "the illness is brief, but fierce."

He classified the typical symptom development as beginning "with a sudden explosive vomiting episode which soon is followed by more vomiting and often diarrhea."

Typically, most people recover within one to three days, with the exceptions of the elderly, immunocompromised people, and some children. "Dehydration is of special concern for the very young and older frail people who may require hospitalization for rehydration," Schaffner said.

While outbreaks most often occur from November to April, Dr. Jatin Vyas, an infectious disease professor at Columbia University Medical School in New York City, told Newsweek in a phone interview Sunday that, given "the majority of illness are related to our food supply," infectious disease experts have begun to "think of norovirus as kind of a year-round process, and there's just kind of blips and valleys."

The CDC has identified leafy vegetables, fresh fruits, and shellfish as a common source of norovirus outbreaks. Newsweek has reached out to the CDC for comment via email on Sunday.

Vyas noted that the virus is "fairly hardy," and "if we freeze our [contaminated] food, it actually could still be contaminated and infectious." On the other hand, "it needs a sustained temperature above 60 degrees Celsius (140 degrees Fahrenheit) to be decontaminated." However, leafy greens like lettuce, which are often sources of contamination, are typically served uncooked in salads.

Best Practices for Preventing Norovirus

A tiny dose of just 10 viral particles can make a person ill, making it one of the most easily transmissible pathogens.

As the virus is "extremely contagious" and spreads very quickly, especially in spaces with groups of people, Schaffner said "good, repeated hand hygiene is the best preventive along with staying away from those who are ill."

Vyas agreed and said that "handwashing is probably the very best thing to do." The CDC encourages people to wash their hands well with soap and water, noting that "hand sanitizer alone does not work well against norovirus."

Given that majority of the illness is passed through contaminated food and fomites, inanimate objects or surfaces that a contaminated individual touched, Vyas doesn't recommend face masking. The virus can stay on surfaces and objects for several hours, and the CDC encourages people to clean and disinfect surfaces.

Schaffner noted that during an investigation into an "outbreak centered on a bridge club," researchers "were able to detect the virus on the surface of playing cards."

Vyas recommended cleaning kitchen items that a contaminated individual or food source may have touched by using dishwashing cycles with heat and soap.

He also noted that washing food, particularly vegetables and fruits, is "good practice, but doesn't necessarily mean you're going to fully prevent it."