This common precaution won't stop norovirus, experts say. Here's what to do instead

With cases of norovirus surging in parts of the United States this winter, according to data from to the Centers for Disease Control and Prevention, how can you protect yourself and your family from being hit with the virus?

While the virus is notoriously difficult to stop, experts say at least one common precaution might not actually work.

That's because hand sanitizer is not very effective at preventing norovirus, according to the CDC.

"The norovirus doesn't get killed with hand sanitizer," said Dr. Mark Loafman, assistant chair of Family and Community Medicine at Cook County Health, told NBC Chicago. "So those alcohol products don't work."

What does?

Washing your hands -- thoroughly. Especially after visits to the bathroom.

"It's one of those times, especially if you have any symptoms, 20 seconds soap and warm water, scrubbing your hands before you leave the bathroom. It's really, really important," Loafman said.

Dr. Whitney Lyn, lead family medicine physician at Sengstacke Health Center of Provident Hospital, said using hand sanitizer alongside hand washing is even better.

The CDC notes that norovirus can found in both vomit and feces "even before you start feeling sick."

"The virus can also stay in your poop for 2 weeks or more after you feel better. You can still spread norovirus during that time," the CDC warned.

Eating raw or undercooked shellfish can also increase the risk of infection. That's because the CDC reports that noroviruses are "relatively resistant to heat and can survive temperatures as high as 145 degrees."

"Quick steaming processes will not heat foods enough to kill noroviruses," the agency notes.

Here's what to know about the virus and the other measures to take to prevent infection and spread:

What is norovirus?

Norovirus -- also referred to as "the stomach bug" or "food poisoning" -- is characterized by sudden vomiting and diarrhea. Outbreaks are often seen on cruise ships, in congregate living situations like nursing homes and jails, as well as schools and places where people are close together.

According to the CDC, norovirus is the leading cause of foodborne illness in the United States, responsible for 58% of such infections acquired in the country each year.

Norovirus infections are caused by a group of viruses that spread easily, with as few as 10 viral particles having the ability to make someone sick, health experts say.

There are about 2,500 norovirus outbreaks reported annually in the United States. The outbreaks can occur throughout the year but are most common from November to April.

How many cases are being reported and where?

The most recent numbers from the CDC show there were 91 outbreaks of norovirus reported during the week of Dec. 5, up from 69 outbreaks the last week of November.

Numbers from the past few years show a maximum of 65 outbreaks reported during that first week of December.

Norovirus outbreaks occur throughout the year, the CDC said, but are most common November through April. Outbreaks typically occur when an infected person spreads the virus through direct contact, like sharing eating utensils or food at a group gathering, holiday party or restaurant.

So far this month, "several small outbreaks" of suspected norovirus cases were reported to the Chicago Department of Public Health, a spokesperson said.

"This is not out of the ordinary for this time of year," the spokesperson added.

What are symptoms of norovirus?

Along with vomiting and diarrhea, the most common symptoms include nausea, stomach pain, body ache, headache and fever.

But one other thing to watch for if you suspect you have norovirus is dehydration.

"If you have norovirus illness, you can feel extremely ill, and vomit or have diarrhea many times a day. This can lead to dehydration (loss of body fluids), especially in young children, older adults, and people with other illnesses," the CDC noted.

Symptoms of dehydration include:

• Decreased urination
• Dry mouth and throat
• Feeling dizzy when standing up
• Crying with few or no tears
• Unusual sleepiness or fussiness

How does norovirus spread?

Most norovirus outbreaks occur when people who are already infected spread the virus to others by direct means, such as through sharing food or eating utensils. Outbreaks can also be spread through food, water or contaminated surfaces.

How long does it last?

Illness caused by norovirus typically starts suddenly, with symptoms developing 12 to 48 hours following exposure to the virus. Most people get better within one to three days and recover fully.

But with 19 to 21 million illnesses each year in the United States, norovirus nevertheless causes on average 900 deaths and 109,000 hospitalizations annually, mostly among adults aged 65 and older. It also leads to 465,000 emergency department visits, mostly involving young children.

How can you treat norovirus?

There is no medication to treat norovirus. Rehydration is recommended by drinking water and other liquids, with the exception of coffee, tea and alcohol.

Anyone suffering from dehydration should seek medical help. Symptoms of dehydration include a decrease in urination, dry mouth and throat, and feeling dizzy when standing. Dehydrated children may be unusually sleepy or fussy and cry with few or no tears.

How to protect yourself from norovirus

Rigorous and frequent handwashing is the best defense against norovirus during the peak winter season, scrubbing the hands with soap and warm water for 20 seconds before meals.

Scrubbing surfaces with household disinfectants can also help.

According to the CDC, if you contract norovirus or live with someone who has, you should:

Clean and disinfect surfaces well

• Wear rubber or disposable gloves and wipe the entire area with paper towels and throw them in a plastic trash bag.
• Disinfect the area
• Leave bleach disinfectant on the affected area for at least 5 minutes.
• Clean the entire area again with soap and hot water.
• Wash laundry, take out the trash, and wash your hands.

Wash laundry well

Immediately remove and wash clothes or linens that may have vomit or poop on them.

• Wear rubber or disposable gloves.
• Handle items carefully without shaking them.
• Wash the items with detergent and hot water at the maximum available cycle length and then machine dry them at the highest heat setting.
• Wash your hands after with soap and water.