Cases of norovirus are surging in parts of the United States this winter, according to data from to the Centers for Disease Control and Prevention, and with holiday gatherings set to continue this week, what should you look for?
The stomach bug has been known to cause vomiting, diarrhea and more.
With the latest outbreaks, officials are urging people to take precautions.
Here's what to know:
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?
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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.
