Stomach flu is an intestinal infection caused by several different viruses that can result in
diarrhea and vomiting. A highly contagious condition, the stomach flu is the second most common illness in the United States. It causes millions of cases of diarrhea each year.
But the so-called "stomach flu" is actually not stomach flu at all. Viruses that cause it affect the small intestine, not the stomach. Furthermore, stomach flu viruses are not flu viruses. The
flu virus is the
influenza virus, which affects the respiratory system. The
influenza virus does not affect the intestines.
Regardless of the inaccuracies of the term "stomach flu," it is the most commonly used term to describe what healthcare providers call viral gastroenteritis.
Anyone can get the stomach flu. It occurs in people of all ages and backgrounds.
Outbreaks can occur in institutional settings, such as schools, childcare facilities, and nursing homes, and it can occur in other group settings, such as banquet halls, cruise ships, dormitories, and campgrounds.
Many different viruses can cause this illness. Some common types of stomach flu viruses include:
Each virus has its own seasonal activity. For example, in the United States, rotavirus and astrovirus infections occur during the cooler months of the year (October to April), whereas adenovirus infections occur throughout the year.
How Is Stomach Flu Spread?
Stomach flu is highly contagious and can spread easily from person to person. These viruses often can be found in the stool or vomit of infected people. Transmission can occur in one of several ways, including:
- Eating foods or drinking liquids that are contaminated with a stomach flu virus
- Having direct contact with another person who is infected and showing symptoms (for example, when caring for someone with the illness, or sharing food or eating utensils with someone who is ill)
- Touching surfaces or objects contaminated with a virus and then putting your hands in your mouth.
(Click Stomach Flu Transmission for more information.)
When a person becomes infected with stomach flu, the virus begins to multiply within the small intestine. After approximately 1 to 2 days (depending on the virus), symptoms can appear. This period between the transmission of the virus and the start of symptoms is the "stomach flu incubation period." In some cases, the incubation period can be as short as 4 hours.
Whether or not a person is contagious during the incubation period will depend on which virus he or she is infected with. For example, with a
rotavirus infection, the person is contagious during the incubation period. He or she is also contagious while experiencing symptoms. Once the
diarrhea has ended, a person with
rotavirus gastroenteritis is no longer contagious.
With a
norovirus infection (including Norwalk virus), a person is not usually contagious during the stomach flu incubation period. People infected with
norovirus gastroenteritis are usually contagious from the moment they begin feeling ill to at least 3 days after recovery. Some people may be contagious for as long as 2 weeks after recovery.
Not all people who are infected with a stomach
flu virus will develop associated symptoms. If symptoms do occur, the illness can begin suddenly. Symptoms of stomach flu can last anywhere from 1 to 10 days, depending on which virus a person is infected with. Symptoms can be mild to severe. The most common symptoms are
diarrhea and vomiting.
In order to make a diagnosis, the healthcare provider will ask a number of questions about a person's medical history and will perform a physical exam, looking for signs and symptoms of stomach flu. If the doctor suspects
rotavirus, he or she may test the stool for it. Besides rotavirus, there are no specific routine lab tests commonly used to identify other stomach flu viruses.
Treatment for Stomach Flu
Stomach flu has no specific treatment; antibiotics are not effective against viruses. Treatment focuses on reducing the symptoms and preventing dehydration while the body fights the infection.
People with stomach flu should rest, drink clear liquids, and eat easy-to-digest foods. For infants and young children, oral rehydration solutions can replace lost fluids, minerals, and salts.
No vaccine is available for stomach flu, with the exception of a newly released
rotavirus vaccine called
RotaTeq®. This oral vaccine for infants aged 6 weeks to 32 weeks was approved in February 2006 by the US Food and Drug Administration (FDA).
Therefore, the best prevention method involves reducing your chances of coming in contact with stomach flu viruses.
Other Names for Stomach Flu
Besides stomach flu, people use a variety of other names to describe a viral infection of the intestines that leads to
diarrhea and vomiting. Some of these other names include:
