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. 

Notes: Dr. Nelson Crumfield

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EditText of this page (last edited June 15, 2010)