Gastroenteritis is often mistaken for stomach flu although it is actually an inflammation of the lining of the intestines caused by a virus, bacteria or parasites.

Symptoms of gastroenteritis include diarrhea, abdominal pain, vomiting, headache, fever and chills. Most people recover with no treatment.

The most common problem with gastroenteritis is dehydration. This happens if you do not drink enough fluids to replace what you lose through vomiting and diarrhea. Dehydration is most common in babies, young children, the elderly and people with weak immune systems.

Bacterial gastroenteritis

Bacterial gastroenteritis can affect one person or a group of people who all ate the same food. It is commonly called food poisoning. It often occurs after eating at picnics, school cafeterias, large social gatherings or restaurants.

Many different types of bacteria can cause bacterial gastroenteritis, including Campylobacter jejuni, E. coli, Salmonella, Shigella, Staphylococcus and Yersinia.

Viral gastroenteritis

Viral gastroenteritis is the second most common illness in the U.S. The cause is often a norovirus infection which spreads through contaminated food or water and/or contact with an infected person. The best prevention is frequent hand washing.

Several different viruses can cause viral gastroenteritis, which is highly contagious and extremely common. Symptoms usually appear within 12-48 hours after exposure to a gastroenteritis-causing virus and last for 1-3 days. Some viruses cause symptoms that last longer.

Viral gastroenteritis is transmitted from person to person. Viruses are present in the stool and vomit of infected people who may contaminate surfaces, objects, food and drinks, especially if they do not wash their hands thoroughly after using the bathroom. When an infected person with unwashed hands touches another person, the virus can spread. When an infected person vomits, the virus can become airborne.

Outbreaks of viral gastroenteritis can occur anyplace where people gather in groups. People who suspect they were exposed to a virus in one of these settings may want to contact a local health department that tracks these outbreaks.

Most cases of viral gastroenteritis are caused by four types of viruses:

  • Rotavirus is the leading cause of gastroenteritis among infants and young children 3-15 months old. It can also infect adults in close contact with these children, but their symptoms are milder.
  • Caliciviruses cause infection in people of all ages. Norovirus, the most common calicivirus and cause of viral gastroenteritis in adults, is usually responsible for epidemics of viral gastroenteritis. Norovirus outbreaks are more frequent from October-April.
  • Adenovirus mainly infects children younger than 2. Of the 49 types of adenoviruses, one strain affects the gastrointestinal tract, causing vomiting and diarrhea. Adenovirus infections occur year-round.
  • Astrovirus primarily infects infants and young children, but may also spread to adults. The symptoms are milder than those of norovirus or rotavirus infections. The virus is most active during the winter months.


Bacterial gastroenteritis

Your health care provider will examine you for signs of food poisoning, including dehydration. Lab tests may be done on the food or a stool sample to find out what germ is causing the symptoms. However, these tests do not always show the cause of the diarrhea. Tests may also be done to look for white blood cells in the stool, which is a sign of infection.

Viral gastroenteritis

Viral gastroenteritis is usually diagnosed based on symptoms alone. People who have symptoms that are severe or last for more than a few days may want to see their doctor for additional tests. A health care provider may ask for a stool sample to test for rotavirus or norovirus or to rule out bacteria or parasites as the cause. During an epidemic of viral gastroenteritis, health care providers or public health officials may test stool samples to find out which virus is responsible for the outbreak.


With gastroenteritis, if you have diarrhea and are unable to drink or keep down fluids because of nausea or vomiting, you may need IV fluids. If you take diuretics (water pills), talk to your doctor about stopping them while you have diarrhea. Children, older adults and adults with weak immune systems may need to drink oral rehydration solutions to prevent dehydration. The primary goal of treatment is to reduce symptoms.

Bacterial gastroenteritis

You will usually recover from the most common types of bacterial gastroenteritis in a couple of days. The goal is to make you feel better and avoid dehydration. Drinking enough fluids and learning what to eat will help ease symptoms. Also get plenty of rest.

Viral gastroenteritis

Most cases of viral gastroenteritis resolve over time without specific treatment. Antibiotics are not effective against viral infections. The primary goal of treatment is reduce and manage symptoms.

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