Gastroenteritis
(Stomach Flu)

• Gastroenteritis Overview
• Gastroenteritis Causes
• Gastroenteritis Symptoms
• When to Seek Medical Care
• Exams and Tests
• Gastroenteritis Treatment
• Self-Care at Home
• Medical Treatment
• Medications
• Next Steps
• Follow-up
• Prevention
• For More Information
• Web Links
• Pictures
• Synonyms and Keywords
• Authors and Editors
• Viewer Comments: Gastroenteritis (Stomach Flu) - Effective Treatments

Gastroenteritis Overview

Gastroenteritis is a condition that causes irritation and inflammation of the stomach and intestines (the gastrointestinal tract). Diarrhea, crampy abdominal pain, nausea, and vomiting are the most common symptoms.

Viral infection is the most common cause of gastroenteritis but bacteria, parasites, and food-borne illness (such as shellfish) can be the offending agent.

Many people who experience the vomiting and diarrhea that develop from these types of infections or irritations think they have "food poisoning," and they may indeed have a food-borne illness. Many people also refer to gastroenteritis as "stomach flu," although influenza has nothing to do with the condition.

Travelers to foreign countries may experience "traveler's diarrhea" from contaminated food and unclean water.

• The severity of infectious gastroenteritis depends on the immune system's ability to resist the infection. Electrolytes (these include essential elements of sodium and potassium) may be lost as you vomit and experience diarrhea.

• Most people recover easily from a short bout with vomiting and diarrhea by drinking fluids and easing back into a normal diet. But for others, such as infants and the elderly, loss of bodily fluid with gastroenteritis can cause dehydration, which is a life-threatening illness unless the condition is treated and fluids restored.

Gastroenteritis Causes

Gastroenteritis has many causes. Viruses and bacteria are the most common.

Viruses and bacteria are very contagious and can spread through contaminated food or water. In up to 50% of diarrheal outbreaks, no specific agent is found. Improper handwashing following a bowel movement or handling a diaper can spread the disease from person to person.

Gastroenteritis caused by viruses may last one to two days. On the other hand, bacterial cases can last for a longer period of time.

Viruses

Fifty to seventy percent of cases of gastroenteritis in adults are caused by the noroviruses.

Rotavirus is the leading cause of infection in children.

Other viruses that cause gastrointestinal symptoms include:

• Adenoviruses
  
  
• Parvoviruses
  
  
• Astroviruses

Bacteria

Bacteria may cause gastroenteritis directly by infecting the walls of the stomach and intestine. As well, some bacteria like Staphylococcus aureus can form a toxin that is the cause of symptoms. Staph is a common type of food poisoning.

Escherichia coli can cause significant problems, and one type of the bacteria, E. coli O157:H7 can also affect kidney function.

Salmonella, Shigella and Campylobacter

Salmonella, Shigella and Campylobacter are also common causes of illness.

• Salmonella - the cause of typhoid fever is contracted from handling poultry or reptiles such as turtles that carry the germs
  
  
• Campylobacter - from the consumption of undercooked meat, unpasteurized milk
  
  
• Shigella - typically spread from person to person

Clostridium difficile

Clostridium difficile (C difficile) bacteria may overgrow in the large intestine after a patient has been on antibiotics for an infection.

Parasites and protozoans

These tiny organisms are less frequently responsible for intestinal irritation. You may become infected by one of these by drinking contaminated water. Swimming pools are common places to come in contact with these parasites. Common parasites include these:

• Giardia - The most frequent cause of waterborne diarrhea, causing giardiasis
  
  
• Cryptosporidium - Affects mostly people with weakened immune systems and causes watery diarrhea

Other common causes

Gastroenteritis that is not contagious to others can be caused by chemical toxins, most often found in seafood, food allergies, heavy metals, antibiotics, and other medications.

Gastroenteritis Symptoms

By definition, gastroenteritis affects both the stomach and the intestines, resulting in both vomiting and diarrhea.

Common symptoms may include:

• Low grade fever to 100°F (37.7°C)
  
  
• Nausea with or without vomiting
  
  
• Mild-to-moderate diarrhea:
  
  
• Crampy painful abdominal bloating

More serious symptoms

• Blood in vomit or stool
  
  
• Vomiting more than 48 hours
  
  
• Fever higher than 101°F (40°C)
  
  
• Swollen abdomen or abdominal pain
  
  
• Dehydration - weakness, lightheadedness, decreased urination, dry skin, dry mouth and lack of sweat and tears are characteristic findings.

When to Seek Medical Care

Most often gastroenteritis is self-limiting, but it can cause significant problems with dehydration. Should that be a concern, contacting your primary care provider is reasonable.

Vomiting blood or having bloody or black bowel movements are not normal, and emergency care should be accessed. Some medications, for example, bismuth subsalicylate (Pepto-Bismol), turns stool black because of the bismuth in the medication.

Fever, increasing severity of abdominal pain, and persistent symptoms should not be ignored and contacting your primary care provider should be considered if these symptoms are present.

Exams and Tests

Gastroenteritis is often self-limiting, and the care is supportive to control symptoms and prevent dehydration. Tests may not be needed.

If the symptoms persist for a prolonged period of time, the physician may want to consider blood and stool tests to determine the cause of the vomiting and diarrhea.

As always, taking a thorough history is of great value, as is the physical examination.

The patient will be asked if other family or friends have similar exposure or symptoms. The doctor will want to know about the duration, frequency, and description of the patient's bowel movements and whether they are vomiting. The patient will be asked how often and the amount they are urinating to help the doctor determine if fluid loss is causing dehydration. Has the patient lost any weight?

The doctor also will take a medical history, including the following:

• Travel history: Travel may suggest E. coli bacterial infection or a parasite infection from something the patient ate or drank.
  
  
• Exposure to poisons or other irritants: Swimming in contaminated water or drinking from suspicious fresh water such as mountain streams or wells may indicate infection from Giardia - an organism found in water that causes diarrhea.
  
  
• Diet change, food preparation habits, and storage: When the disease occurs following exposure to undercooked or improperly stored or prepared food such as potato salad at a picnic, food poisoning must be considered. In general, symptoms caused by bacteria or their toxins will become apparent after the following amount of time:
  
  
  • Staphylococcus aureus in 2-6 hours
    
    
  • Clostridium 8-10 hours
    
    
  • Salmonella in 12-72 hours
    
    
• Medications: If the patient has used broad-spectrum or multiple antibiotics recently, they may have antibiotic-associated irritation of the gastrointestinal tract.

Physical examination will look for the reasons for symptoms that may not be related to infection. If there are specific tender areas in the abdomen, the doctor will want to determine if the patient has appendicitis, gallbladder disease, pancreatitis, diverticulitis, or other conditions that may be the cause of the patient's symptoms.

Other noninfectious gastrointestinal diseases like Crohn's disease or ulcerative colitis must also be considered. The doctor also will feel the abdomen for masses. A rectal examination may be considered, in which the physician inspects the anus for any abnormalities and then inserts a finger in to the rectum to feel for masses. Stool obtained during this test may be tested for the presence of blood.

The doctor may perform other lab tests, including a complete blood count, electrolytes, and kidney function tests. Stool samples may be tested for blood and different types of infection,

Gastroenteritis Treatment

Self-Care at Home

The mainstay of home treatment of gastroenteritis is hydration. Dehydration will make the symptoms of nausea and vomiting worse and compound symptoms.

Clear fluids should be consumed for the first 24 hours, then gradually progress the diet as tolerated. Clear fluids are anything you can see through. Popsicles and jell-o work well, since they are ingested slowly. Drinking too much fluid too quickly will distend the stomach and worsen the nausea.

Dehydration in children

For dehydration in children, they should be given oral rehydration solutions such as Pedialyte, Rehydrate, Resol, and Rice-Lyte. They contain a good balance of electrolytes that allow better absorption in the stomach than water alone. As well, rehydration with plain water can affect the sodium concentration in the body and lead to seizures.

• After each loose stool, children younger than two years should be given 1-3 ounces of any of the rehydration solutions. Older children should be asked to drink 3-8 ounces. Adults should drink as much as possible.
  
  
• This guideline serves only to replace fluid loss due to diarrhea. Drink additional fluid equal to the amount the patient normally drink.
  
  
• In underdeveloped nations or regions without available commercial pediatric drinks, the World Health Organization has established a field recipe for fluid rehydration:
  
  
  • Mix 2 tablespoons of sugar (or honey) with ¼ teaspoon of table salt and ¼ teaspoon of baking soda. (Baking soda may be substituted with ¼ teaspoon of table salt.) Mix mixture in 1 liter (1 qt) of clean or previously boiled water.
    
    
• After 24 hours, begin to offer bland foods with the BRAT diet - bananas, rice, applesauce without sugar, toast, pasta, or potatoes.

Dehydration in adults

Although adults and adolescents have a larger electrolyte reserve than children, electrolyte imbalance and dehydration may still occur as fluid is lost through vomiting and diarrhea. Severe symptoms and dehydration usually develop as complications of medication use or chronic diseases such as diabetes or kidney failure, however, symptoms may occur in healthy people.

• Clear fluids are appropriate for the first 24 hours to maintain adequate hydration.
  
  
• After 24 hours of fluid diet without vomiting, begin a soft-bland solid diet such as the BRAT diet.

Medical Treatment

Upon seeking medical attention, if the patient cannot take fluids by mouth because of vomiting, the doctor may insert an IV to put fluid back into the body (rehydration).

In infants, depending upon the level of dehydration, intravenous fluids may be delayed to consider trying oral rehydration therapy. Frequent feedings, as small as a 1/6 ounce (5cc) at a time, may be used to restore hydration.

Medications

Doctors usually don't prescribe antibiotics until bacteria have been identified. Antibiotics may be given for certain bacteria, specifically Campylobacter, Shigella, and Vibrio cholerae, if properly identified through laboratory testing. Otherwise, using any antibiotic or the wrong antibiotic can worsen some infections or make them last longer.

Some infections, like salmonella, are not treated with antibiotics. With supportive care of fluids and rest, the body is able to resolve the infection without antibiotics.

For adults, the doctor may give medications to stop vomiting (antiemetics) such as promethazine (Phenergan, Anergan), prochlorperazine (Compazine), or ondansetron (Zofran). Sometimes these medications are prescribed as a suppository. Doctors usually do not recommend antiemetics for infants. Children who are a little older may be offered antiemetic medication.

Doctors generally avoid antidiarrheal medications for all age groups if they suspect the infection is caused by a toxin. The most common antidiarrheal agents for people older than three years are over-the-counter medications such as diphenoxylate atropine (Lomotil, Lofene, Lonox) or loperamide hydrochloride (Imodium).

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Learn more about medications like promethazine (Phenergan, Anergan), and prochlorperazine (Compazine), and ondansetron (Zofran) on RxList.com.

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Next Steps

Diarrhea is one of the leading causes of infant sickness. Worldwide, diarrhea accounts for 3-5 million deaths yearly for all age groups. In general, most adults and children recover after they are appropriately rehydrated.

Follow-up

• After an infection or irritation of the digestive tract, the patient may not be able to eat a regular diet. Some people may be unable to tolerate dairy products for several weeks after the disease has run its course. The patient should continue to advance slowly from bland nondairy soups and grain products to a solid diet.
  
  
• If symptoms continue or worsen, call a doctor.
  
  
• Food handlers should not return to work until their symptoms have resolved. Salmonella infections are a special case; those who work in the medical profession or who are food handlers need to have negative stool cultures for Salmonella before being allowed to return to work.

Prevention

With most infections, the key is to block the spread of the organism.

• Always wash your hands.
  
  
• Eat properly prepared and stored food.
  
  
• Bleach soiled laundry.
  
  
• Vaccinations for Salmonella typhi, Vibrio cholerae, and rotavirus have been developed. Rotavirus vaccination is recommended for infants in the U.S. Vaccines for S. typhi and V. cholerae may be administered to individuals traveling in at-risk areas.

For More Information

Web Links

National Center for Infectious Diseases, Respiratory and Enteric Viruses Branch, Viral Gastroenteritis

Centers for Disease Control and Prevention, Safe Food and Water

Pictures

Media file 1: Cryptococcus colitis (shown at the arrows). Image courtesy of Alexis Carter, MD, Department of Pathology and Laboratory Medicine, East Carolina University.

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Media file 2: Pathological changes seen in intestinal lumen with pseudomembranous colitis (indicated by arrows). Image courtesy of Alexis Carter, MD, Department of Pathology and Laboratory Medicine, East Carolina University.

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Media file 3: Strongyloides stercoralis parasite (highlighted by arrows). Image courtesy of Alexis Carter, MD, Department of Pathology and Laboratory Medicine, East Carolina University.

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Media file 4: Giardia lamblia (indicated by the arrows). Image courtesy of Alexis Carter, MD, Department of Pathology and Laboratory Medicine, East Carolina University.

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Media file 5: Normal stain of stool sample looking for ova, parasites, and leukocytes. Image courtesy of Alexis Carter, MD, Department of Pathology and Laboratory Medicine, East Carolina University.

Media type: Photo

Synonyms and Keywords

stomach flu, intestinal flu, dysentery, infectious diarrhea, diarrhea, traveler's diarrhea, lactose intolerance, adenoviruses, rotaviruses, calciviruses, astroviruses, Norovirus, Norwalk-like virus, Norwalk virus, Escherichia coli, E coli, Salmonella, Campylobacter, Shigella, Giardia, Cryptosporidium, food poisoning, symptoms of stomach flu, stomach flu symptoms, flu symptoms, vomiting, infectious gastroenteritis, improper handwashing, giardiasis, abdomen tenderness, gastrointestinal disease, dehydration, infection of the digestive tract, digestive tract, viral gastroenteritis, gastroenteritis

Authors and Editors

Author: Benjamin C. Wedro, MD, FAAEM

Editor: Melissa Conrad Stoppler, MD

Previous contributing authors and editors: Author: Jason Gardiner, MD, Staff Physician, Department of Emergency Medicine, Pitt County Memorial Hospital, East Carolina University.

Coauthor(s): Charles Brown, MD, FACEP, Program Director, Associate Professor, Department of Emergency Medicine, Pitt County Memorial Hospital, East Carolina University.

Editors: Scott H Plantz, MD, FAAEM, Research Director, Assistant Professor, Department of Emergency Medicine, Mount Sinai School of Medicine; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Ron Fuerst, MD, Clinical Assistant Professor, Department of Pediatrics, University of South Carolina College of Medicine; Director, Children's Emergency Center, Children's Hospital of Richland Memorial Hospital.

Last Editorial Review: 6/6/2008