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What Is Viral Gastroenteritis?
Viral gastroenteritis is an intestinal infection caused by several different viruses. These conditions are highly contagious and cause millions of cases of diarrhea each year.
Anyone can get viral gastroenteritis and most people recover without any complications. However, viral gastroenteritis can be serious for people who cannot drink enough fluids to replace what is lost through vomiting and diarrhea, especially infants, young children, the elderly, and people with weak immune systems. Complications from vomiting also can occur, even in healthy people.
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What Are the Symptoms of Viral Gastroenteritis?
The main symptoms of viral gastroenteritis are watery diarrhea and vomiting. Other symptoms are headache, fever, chills, and abdominal pain. The symptoms may appear within hours or a few days of infection. They usually last for 1 to 2 days, but may last as long as 10 days.
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What Causes Viral Gastroenteritis?
The viruses that cause viral gastroenteritis damage the cells in the lining of the small intestine. As a result, fluids leak from the cells into the intestine and produce watery diarrhea. Four types of viruses cause most viral gastroenteritis:
- Rotavirus is the leading cause of gastroenteritis among children 3 to 15 months old. Most children have been exposed to the virus by age 2. Children with rotavirus have vomiting and watery diarrhea for 3 to 8 days, along with fever and abdominal pain. Rotavirus can also infect adults who are in close contact with infected children, but the symptoms in adults are milder. Symptoms of rotavirus infection appear 1 to 2 days after exposure. Rotavirus infections are most common from November to April.
- Adenovirus serotypes 40 and 41 cause gastroenteritis mainly in children younger than 2 years old. Infections occur all year round; vomiting and diarrhea appear approximately 1 week after exposure.
- Caliciviruses cause infection in persons of all ages. This family of viruses is further divided into the noroviruses (example, Norwalk virus) and the sapoviruses (example, Sapporo virus). Caliciviruses are transmitted from person to person and also through contaminated water or food--especially oysters from contaminated waters. The noroviruses are often responsible for epidemics of viral gastroenteritis. In addition to vomiting and diarrhea, people infected with caliciviruses may have muscle aches. The symptoms appear within 1 to 3 days of exposure. The Norwalk virus has recently been blamed for several outbreaks of gastroenteritis on cruise ships.
- Astrovirus also infects primarily infants, young children, and the elderly. This virus is most active during the winter months. Vomiting and diarrhea appear within 1 to 3 days of exposure.
Viral gastroenteritis is often mistakenly called the "stomach flu," but the influenza virus does not cause it and it does not infect the stomach.
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How Does Viral Gastroenteritis Spread?
Viral gastroenteritis is highly contagious. The viruses are often transmitted on unwashed hands. People can get the viruses through close contact with infected individuals, such as sharing their food, drink, or eating utensils, or by eating food or drinking beverages that are contaminated with the virus. People who no longer have symptoms may still be contagious, since the virus can be found in the stool for up to 2 weeks after they recover from their illness. Also, people can become infected without having symptoms, and they can still spread the infection.
Outbreaks of viral gastroenteritis can occur in childcare settings, schools, nursing homes, cruise ships, camps, dormitories, restaurants, and other places where people gather in groups. If you suspect that you were exposed to a virus in one of these settings, you may want to contact your local health department, which tracks outbreaks.
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How is Viral Gastroenteritis Diagnosed?
If you think you have viral gastroenteritis, you may want to see your doctor, although many people don't bother. Doctors generally diagnose viral gastroenteritis based on the symptoms and a physical examination. Your doctor may ask for a stool sample to test for rotavirus or to rule out bacteria or parasites as the cause of your symptoms. No routine tests are currently available for the other types of viruses.
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How is Viral Gastroenteritis Treated?
Most cases of viral gastroenteritis resolve over time without specific treatment. Antibiotics are not effective against viral infections. The primary goal of treatment is to reduce the symptoms, and prompt treatment may be needed to prevent dehydration.
Your body needs fluids to function. Dehydration is the loss of fluids from the body. Important salts or minerals, known as electrolytes, can also be lost with the fluids. Dehydration can be caused by diarrhea, vomiting, excessive urination, or excessive sweating, or by not drinking enough fluids because of nausea, difficulty swallowing, or loss of appetite.
In viral gastroenteritis, the combination of diarrhea and vomiting can cause dehydration. The symptoms of dehydration are:
- Excessive thirst
- Dry mouth
- Little or no urine or dark yellow urine
- Decreased tears
- Severe weakness or lethargy
- Dizziness or lightheadedness
If you notice any of these symptoms, you should talk to your doctor. Mild dehydration can be treated by drinking liquids. Severe dehydration may require intravenous fluids and hospitalization. Untreated severe dehydration can be life threatening.
Children present special concerns. Because of their smaller body size, infants and children are at greater risk of dehydration from diarrhea and vomiting. Oral rehydration solutions such as Pedialyte can replace lost fluids, minerals, and salts. Learn more about dehydration…
You can take several steps to help relieve the symptoms of viral gastroenteritis:
- Allow your gastrointestinal tract to settle by not eating for a few hours.
- Sip small amounts of clear liquids or suck on ice chips if vomiting is still a problem.
- Give infants and children oral rehydration solutions to replace fluids and lost electrolytes.
- Gradually reintroduce food, starting with bland, easy-to-digest food, like toast, broth, apples, bananas, and rice.
- Avoid dairy products, caffeine, and alcohol until recovery is complete.
- Get plenty of rest.
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How Can I Prevent Viral Gastroenteritis?
Prevention is the only way to avoid viral gastroenteritis. There is no vaccine available. You can avoid it by:
- Washing your hands thoroughly after using the bathroom or changing diapers
- Washing your hands thoroughly before eating
- Disinfecting contaminated surfaces
- Not eating or drinking foods or liquids that might be contaminated
New vaccines under development may decrease the risk of infection, especially among infants and young children.
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Points to Remember
- Viral gastroenteritis is a highly contagious infection of the intestines caused by one of several viruses.
- Although it is sometimes called "stomach flu," viral gastroenteritis is not caused by the influenza virus and does not affect the stomach.
- The main symptoms are watery diarrhea and vomiting.
- Anyone can get viral gastroenteritis through unwashed hands, close contact with an infected person, or food and beverages that contain the virus.
- Diagnosis is based on the symptoms and a physical examination. Currently only rotavirus can be rapidly detected in a stool test.
- Viral gastroenteritis has no specific treatment; antibiotics are not effective against viruses. Treatment focuses on reducing the symptoms and preventing dehydration.
- The symptoms of dehydration are excessive thirst, dry mouth, dark yellow urine or little or no urine, decreased tears, severe weakness or lethargy, and dizziness or lightheadedness.
- Infants, young children, the elderly, and people with weak immune systems have a higher risk of developing dehydration due to vomiting and diarrhea.
- People with viral gastroenteritis 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.
- Avoid viral gastroenteritis by washing hands thoroughly after using the bathroom or changing diapers, disinfecting contaminated surfaces, and avoiding foods or liquids that might be contaminated.
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This article is based on information from the National Institute of Diabetes and Digestive and Kidney Diseases, which is part of the National Institutes of Health.
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