There's a norovirus outbreak. Here's how to avoid it — and what to do if you catch it.

Norovirus, aka the “stomach flu,” is on the rise in the U.S. New data from the Centers for Disease Control and Prevention found that more than 12% of tests for norovirus came back positive the week of Feb. 17 — up from from 11.5% the week before. Experts say that’s a concern given that norovirus is highly contagious. According to the CDC, it causes more than 19 million illnesses, mostly in young children, annually in the country, and leads to 465,000 emergency department visits. Lowering your risk for getting norovirus is important, especially if you are in one of the vulnerable populations for this illness.

How can you prevent norovirus and what should you do if you get it? Here’s what experts want you to know.

What is norovirus? How is it different from the flu?

Dr. Nipunie Rajapakse, a pediatric infectious diseases physician with the Mayo Clinic Children’s Center, tells Yahoo Life that norovirus is unrelated to influenza, despite its nickname. Instead, norovirus is “a type of virus that causes gastroenteritis or ‘stomach flu.’”

“Norovirus is also known as the cruise ship virus because of its frequent outbreaks on cruise ships and military bases — and it’s circulating everywhere,” Dr. Craig Wilen, associate professor in laboratory medicine and immunobiology at the Yale School of Medicine, tells Yahoo Life. “We have no drugs or vaccines for it, so it’s a major public health burden.”

Unlike the flu, which often includes respiratory symptoms like a cough, gastroenteritis attacks your intestines, says Rajapakse, causing inflammation. This causes symptoms such as:

watery, usually non-bloody diarrhea

nausea

vomiting

stomach cramps and pain

occasional muscle aches

headache

a low-grade fever

Nausea and vomiting are the two big signs that you have norovirus, and these symptoms typically last one to two days. One of the risks of these symptoms is dehydration, which is a concern if a person is not hydrating properly or keeping fluids down. This is particularly dangerous for young children, the elderly and those who are immunosuppressed, Wilen says.

If you have norovirus, there’s typically no reason to see a doctor unless you find yourself suffering from dehydration, signs of which include going to the bathroom less often, dry mouth and dizziness in adults, according to the CDC. “Fluids and electrolytes is what you need, as well as trying your best not to spread the illness to household contacts, which is more difficult than one might think,” Wilen says. Over-the-counter antidiarrheal medications can also help.

“We don’t have many tools in the toolbox to avoid spread, unfortunately,” says Wilen, “but the good news is that most cases will clear up in a few days.”

How can you avoid getting norovirus?

Norovirus is “largely spread through the fecal-oral route,” Wilen explains. “Virus that’s either in the stool or in the vomit will either get on someone’s hands or a food product, and then get into the mouth or gastrointestinal tract of the recipient.”

Keeping your hands clean is key. While spraying your hands with sanitizer may be a go-to move since the pandemic started, it’s not going to do much when it comes to avoiding the norovirus, says Wilen. That’s because “the virus is relatively resistant to ethanol-based cleaners, like hand sanitizer,” he says. Instead, washing your hands with soap and warm water, particularly after using the bathroom or before preparing food, is your best move for avoiding transferring the virus from your hands. You should also make sure to avoid sharing any food with someone who may be infected.

In order to kill the virus on surfaces in the home, Wilen suggests using bleach-based cleaning products. Or you can make your own using a mixture of 5-25 tablespoons of household bleach to 1 gallon water, per the Mayo Clinic.

Also according to the Mayo Clinic, you can follow these tips to avoid spreading or catching norovirus:

Wash hands with soap and water for at least 20 seconds.

Clean fruits and vegetables before eating.

Cook food thoroughly. (Foodsafety.gov provides an internal food temperature chart for cooking.)

If you’re sick, stay home and avoid others.

Avoid preparing food for others if you are sick with vomiting/diarrhea.

Disinfect surfaces and counters that may be contaminated.