Norovirus Cases Are on the Rise Across US: What You Need to Know

Transmission electron micrograph shows norovirus particles in an undated file photo. Charles D. Humphrey/US Centers for Disease Control and Prevention

Norovirus, a highly contagious stomach virus, is continuing to spread across the United States and is resulting in the shutting down of schools in some locales.

Recent data from the Centers for Disease Control and Prevention (CDC) suggests positive tests for the virus are at a seasonal high across the United States. At the regional level, test positivity spikes are occurring in the Northeast at over 16 percent, the South at over 16 percent, the West at over 12.5 percent, and about 15 percent in the Midwest.

Two Petersburg, Virginia, elementary schools shut down on Feb. 17 over the virus. Authorities said it spread quickly among students, who have been instructed to log in and complete their school assignments at home.

Positive-polarity RNA virus called the Norovirus. Debbink et al./PLoS Pathog [CC BY-SA 2.0]

“Pleasants Lane and Lakemont Elementary School will be closed for a deep cleaning due to a gastrointestinal illness outbreak at both schools,” a Petersburg Schools spokesperson told local media on Friday. “The custodial staff is concentrating on cleaning areas of high contact in order to minimize the possibility of transmission.”

Around the same time, the Southern Nevada Health District on Feb. 17 confirmed 71 cases of norovirus at Wayne N. Tanaka Elementary in the Las Vegas area, local outlets reported. A letter was sent home to parents last week, but classes were not canceled as a result.

Several days ago, classes at a suburban Detroit school were canceled due to an outbreak of the virus among students and staff. St. Michael the Archangel Catholic School in Livonia shut down Wednesday, officials told WXYZ-TV.

A school principal told the Detroit Free Press that they believe that about 115 students and staff at St. Michael were sickened this month.

“The first couple of kids were sick Monday. And then on Tuesday, we had in one class ... about 10 or 12 kids who started throwing up over the course of four hours,” Kathy Nold, a co-principal, told the paper.

In Canada, the Public Health Agency of Canada told media outlets that reported cases of norovirus have been increasing “both at the national level and within several provinces” since January. Nearly every Canadian province has experienced an increase, according to the agency, including Newfoundland and Labrador, British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, and New Brunswick.

What Medical Officials Say

In a Sunday opinion article, Fox News’ Dr. Nicole Saphier wrote that “the number of infections this year outpace the last few years, but decreased congregation from the COVID-19 pandemic most likely contributed to the lower-case counts, and we are now experiencing normal trends preceding COVID-19.”

“Each year, one in every 15 individuals in the U.S. will get norovirus stomach flu; it’s hard to avoid,” Saphier wrote, noting how common the virus is. “If you do get sick, make sure to stay in touch with your doctor and drink plenty of fluids to decrease the risk of dehydration and the consequences of fluid depletion. Do what you can to stop the spread by keeping contaminated surfaces clean and avoiding group settings until 48 hours after symptoms have completely resolved.”

Another doctor, located in Boston, echoed Saphier’s statement in saying that norovirus is on the rise because COVID-19 rules have disappeared.

“The recent norovirus cases are probably another example of seeing re-emergence of common infections as we continue to emerge from our COVID-19 shells,” Dr. Daniel Kuritzkes, of Brigham and Women’s Hospital, told NBC10 last week. “There were periodic localized outbreaks of norovirus infection all the time pre-COVID, so not surprising that we’re seeing them again.”

Dr. Paul Pottinger, professor in the division of allergy and infectious diseases at UW Medicine in Seattle, said this month that the current “seasonal increase in transmission probably relates to crowding of people together inside, where we are more likely to come into contact with each other, and with objects we have touched.”

What Is Norovirus?

In a normal year, according to the CDC, norovirus causes between 19 and 21 million cases of vomiting and diarrhea, 109,000 hospitalizations, and 900 deaths across the United States. The virus also is associated with about 495,000 emergency department visits, mostly in younger children, the CDC says.

Most outbreaks occur between November and April, the CDC adds. If there is a new strain of the virus, it says, there can be upwards of 50 percent more norovirus illness.

Norovirus outbreaks often occur in healthcare facilities, long-term care facilities, restaurants, childcare centers, schools, and cruise ships.

Noting the association between norovirus outbreaks and cruises, the CDC says that more than 90 percent of “outbreaks of diarrheal disease on cruise ships” are caused by the virus.

“These outbreaks often get media attention, which is why some people call norovirus the ‘cruise ship virus,’” the CDC’s website states. However, norovirus outbreaks on cruise ships account for only a small percentage (1 percent) of all reported norovirus outbreaks. Norovirus can be especially challenging to control on cruise ships because of the close living quarters, shared dining areas, and rapid turnover of passengers.”