It's norovirus, which attacks the stomach and intestines.
As The Early Show medical correspondent Dr. Emily Senay explains, norovirus is frequently called stomach flu, but it's not actually a flu virus.
Norovirus can make a person very uncomfortable. Symptoms include vomiting and diarrhea, and commonly last for two or three days.
It's estimated that, in a typical year in the United States, 23 million people are infected, some 50,000 of them are hospitalized, and 300 die.
The federal Centers for Disease Control and Prevention and state health authorities don't keep detailed statistics on norovirus, but a CDC epidemiologist tells Dr. Senay the number of informal inquiries he's received suggests there's increased activity this year in locations across the country.
The CDC has prepared a detailed fact sheet on norovirus. To see it, click here.
Norovirus tends to cause large amounts of illness in areas where people are somewhat confined. Once the virus settles into a nursing home, say, or a hospital, it can be hard to get rid of.
When illness sweeps through a cruise ship, norovirus may well be the cause.
And, Dr. Senay points out, that makes sense: In all of those places, people who get sick have no place else to go, so they can easily infect others.
Food is a major source of norovirus transmission, she continues. If someone preparing food is infected, then people eating that food can get sick. It can also spread if surfaces on which food is prepared contain the virus. Sharing food or utensils with an infected person can lead to illness. So can eating foods that aren't cooked well enough, or raw fruits and vegetables that aren't thoroughly washed.
To prevent infection, Dr. Senay observes, the No. 1 precaution is to wash your hands frequently with soap and water, especially if you handle food a lot, or you're a caregiver for other people
If you're infected, let someone else prepare meals for at least a few days. You can remain contagious for a couple of weeks. Wash contaminated clothing and sheets and towels in hot water, at least 140 degrees Fahrenheit, or in bleach, or both. And make an extra effort to keep surfaces in your home clean.
This is one of those viruses (rotavirus is another) that can survive for extended periods on household surfaces if you're not diligent about removing them. Norovirus can be as difficult to eradicate as a bacterium called c.difficle, which has been infecting many hospitals.
As far as disinfecting surfaces of norovirus is concerned, the CDC cautions that some commonly used household disinfectants just don't get the job done.
A product that does appear to work is chlorine bleach. So, you should use either bleach or a special, Environmental Protection Agency-approved disinfectant. Don't skimp on the bleach. Use about a third of a cup for every gallon of water. And don't overlook any surfaces in your home where viruses can be. Clean countertops, utensils, faucets, toilets, even the floor. In a word — everything! If you've missed a surface, you haven't eliminated the risk of illness.
If you do get infected, the virus will need time to run its course, whatever you do, Dr. Senay notes. But an important precaution is to drink plenty of fluids. With all that's coming out of your body one way or the other, to avoid dehydration, you need to make sure fluids are also going in.