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Stomach Flu

The stomach flu is not really a flu. Rather, the stomach flu is a viral infection caused by several different viruses, such as Norwalk virus and rotavirus. Symptoms of stomach flu are similar, regardless of the virus that causes it, and include diarrhea and vomiting. Treatment usually consists of managing the symptoms while the body fights off the infection.

 

What Is Stomach Flu?

Stomach flu is an intestinal infection caused by several different viruses that can result in diarrhea and vomiting. Highly contagious, 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 stomach flu 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.
 

Stomach Flu and Who It Affects

Anyone can get the stomach flu. Stomach flu occurs in people of all ages and backgrounds.
 
Stomach flu 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.
 

Types of Stomach Flu Viruses

Many different viruses can cause stomach flu. Some common types of stomach flu viruses include:
 
  • Rotavirus
  • Adenovirus
  • Caliciviruses
  • Norwalk virus
  • Noroviruses (see Norovirus)
  • Astrovirus.
     
Each stomach flu 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. Stomach flu 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 stomach flu virus and then putting your hands in your mouth.
     

Incubation Period for Stomach Flu

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), stomach flu symptoms can appear. This period between the transmission of stomach flu and the start of symptoms is the "stomach flu incubation period." In some cases, the stomach flu incubation period can be as short as 4 hours.
 

Contagious Period of Stomach Flu

Whether or not a person is contagious during the stomach flu incubation period will depend on which stomach flu virus he or she is infected with. For example, with a rotavirus infection, the person is contagious during the stomach flu incubation period. He or she is also contagious while experiencing stomach flu 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.
 

Symptoms of Stomach Flu

Not all people who are infected with a stomach flu virus will develop associated symptoms. If stomach flu 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. Stomach flu symptoms can be mild to severe. The most common stomach flu symptoms are diarrhea and vomiting.
 

Diagnosing Stomach Flu

In order to make a stomach flu diagnosis, the doctor 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. Stomach flu 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.
 

Methods of Stomach Flu Prevention

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 stomach flu 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:
 
  • Viral gastroenteritis (gastroenteritis refers to an inflammation of the stomach and intestines)
  • Acute gastroenteritis
  • Non-bacterial gastroenteritis
  • Food poisoning (although there are other causes of food poisoning)
  • Stomach virus
  • 24-hour stomach virus
  • Rotavirus gastroenteritis
  • Norovirus gastroenteritis.
     
Written by/reviewed by: Arthur Schoenstadt, MD
Last reviewed by: Arthur Schoenstadt, MD