NORTHAMPTON — This winter, it may seem like everyone knows someone stuck in bed with a stomach bug.

While the holiday season tends to bring large gatherings and travels that help illness spread, health experts believe that a new norovirus strain could be behind an unusual uptick in stomach upsets.

“Usually in the winter months, we see it,” said Sundeep M. Shukla, associate chief medical officer, vice president of medical affairs and emergency medicine attending physician at Cooley Dickinson Hospital. But this year, he said, norovirus is spreading “rapidly,” with more and more cases popping up.

What could be to blame is this winter’s dominant norovirus strain, deemed GII.17[P17]. Previously, Shukla explained, norovirus outbreaks were primarily caused by a different strain, and national health experts are hypothesizing that the emergence of GII.17[P17] may explain the prevalence of cases this year.

According to the U.S. Centers for Disease Control and Prevention, norovirus causes 58% of food-borne illnesses acquired within the United States, and is the leading cause of vomiting and diarrhea from acute gastrointeritis — inflammation of the stomach and intestines — among people of all ages in the United States. Norovirus is responsible for about 2,270,000 outpatient clinic visits annually, mostly for young children.

Foods commonly involved in norovirus outbreaks are fresh fruits, leafy greens and shellfish, but norovirus is often spread among people through direct contact as well.

Shukla said that the primary symptoms of norovirus are vomiting, diarrhea and cramping, which typically have a quick onset. The illness usually lasts one to three days, but can vary for each person.

While there isn’t a cure for norovirus, there are measures people can take to protect themselves from acquiring it, and to regain their health if they become ill with it.

“Norovirus has an outer protective shell, making alcohol-based hand sanitizers less effective, so you actually have to wash your hands with soap and water,” said Shukla, who advised washing with hot water and soap for at least 20 seconds.

Shukla also said the virus can survive on surfaces and in the air for many days, allowing it to easily spread. To mitigate this risk, a bleach solution is recommended to wipe down surfaces.

Limiting contact with others who have the virus is also ideal, but for those caring for someone with norovirus, Shukla advised wearing gloves, frequently washing your hands and wiping down surfaces often.

Shukla explained that those at most risk of contracting norovirus are those who live in close quarters with others, such as people in college dorms. Norovirus also has been known for spreading rapidly through cruise ships.

“If your child is sick, please keep them at home,” said Shukla, adding that if you find yourself sick, it is best to stay home from work as well. “It’s important that we protect each other.”

For those who come down with norovirus, it’s important not only to hydrate, but to replenish sugar and salt, as drinking only water can actually make certain depletions caused by vomiting and diarrhea worse, advised Jennifer Schimmel, a physician in the department of infectious disease at Baystate Health.

Schimmel works primarily with those admitted for inpatient care, and said that when individuals are admitted due to norovirus, dehydration is usually their worst symptom, “which can occur because of the diarrhea and vomiting.”

In the inpatient care sphere, Schimmel hasn’t seen much change this year in the number of admissions for norovirus or the severity of cases. As in previous years, Schimmel said those hospitalized for norovirus infections have most often been people who are immunocompromised, young children and seniors.

For the vast majority of norovirus patients, who will stay at home on the road to recovery, Schimmel said what’s important is “trying to stay hydrated with small sips of broth or electrolytes,” and also ensuring that all members of the household are washing their hands and wiping down surfaces regularly.

“People can still spread norovirus for up to a few weeks after they feel better,” said Schimmel, who added that she has unfortunately experienced this within her own household before. But when it comes to staying healthy, she said that regular hand washing with soap and water “can go a long way.”

Alexa Lewis can be reached at alewis@gazettenet.com.