William C. Shiel Jr., MD, FACP, FACR
Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.
In this Article
- Take the Tummy Trouble Quiz
- Boost Digestive Health
- Foods That Trigger Diarrhea
- Find a local Gastroenterologist in your town
Viral gastroenteritis (viral infection of the stomach and the small intestine) is the most common cause of acute diarrhea worldwide.
Symptoms of viral gastroenteritis typically last only 48-72 hours and include:
- abdominal cramps, and
Unlike bacterial enterocolitis (bacterial infection of the small intestine and colon), patients with viral gastroenteritis usually do not have blood or pus in their stools and have little if any fever.
Viral gastroenteritis can occur in a sporadic form (in a single individual) or in an epidemic form (among groups of individuals).
- Sporadic diarrhea probably is caused by several different viruses and is believed to be spread by person-to-person contact.
- The most common cause of epidemic diarrhea (for example, on cruise ships) is infection with a family of viruses known as caliciviruses of which the genus norovirus is the most common (for example, "Norwalk agent").
The caliciviruses are transmitted by food that is contaminated by sick food-handlers or by person-to-person contact.
Disease-causing bacteria usually invade the small intestines and colon and cause enterocolitis (inflammation of the small intestine and colon). Bacterial enterocolitis is characterized by signs of inflammation (blood or pus in the stool, fever, abdominal tenderness), as well as abdominal pain and diarrhea. Campylobacter jejuni is the most common bacterium that causes acute enterocolitis in the U.S. Other bacteria that cause enterocolitis include Shigella, Salmonella, and EPEC. These bacteria usually are acquired by drinking contaminated water or eating contaminated foods such as vegetables, poultry, and dairy products.
Enterocolitis caused by the bacterium Clostridium difficile is unusual because it often is caused by antibiotic treatment. Clostridium difficile is also the most common nosocomial infection (infection acquired while in the hospital) to cause diarrhea. Unfortunately, infection also is increasing among individuals who have neither taken antibiotics nor have been in the hospital.
E. coli O157:H7 is a strain of E. coli that produces a toxin that causes hemorrhagic enterocolitis (enterocolitis with bleeding). There was a famous outbreak of hemorrhagic enterocolitis in the U.S. traced to contaminated ground beef in hamburgers (hence, it is also called hamburger colitis). A small percentage of patients infected with E. coli O157:H7, particularly children, can develop hemolytic uremic syndrome (HUS), a syndrome that can lead to kidney failure. Some evidence suggests that prolonged use of anti-diarrhea agents or use of antibiotics may increase the chance of developing HUS.
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