Diarrhea (cont.)
What are common causes of acute diarrhea?
The most common cause of acute diarrhea is infection--viral, bacterial, and
parasitic. Bacteria also can cause acute food poisoning. A third
important cause of acute diarrhea
is starting a new medication.
Viral gastroenteritis
Viral gastroenteritis (viral infection of the stomach and the small
intestine) is the most common cause of acute diarrhea worldwide. Symptoms of
viral gastroenteritis (nausea,
vomiting, abdominal cramps, and diarrhea)
typically last only 48-72 hrs. 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.
Food poisoning
Food poisoning is a brief illness that is caused by toxins produced by
bacteria. The toxins cause abdominal pain
(cramps) and vomiting and also cause the small intestine to secrete large
amounts of water that leads to diarrhea. The symptoms of food poisoning usually
last less than 24 hours. With some bacteria, the toxins are produced in the food
before it is eaten, while with other bacteria, the toxins are produced in the
intestine after the food is eaten.
Symptoms usually appear within several hours
when food poisoning is caused by toxins that are formed in the food before it is
eaten. It takes longer for symptoms to develop when the toxins are formed in the
intestine (because it takes time for the bacteria to produce the toxins).
Therefore, in the latter case, symptoms usually appear after 7-15 hours.
Staphylococcus aureus is an example of a bacterium that produces toxins in
food before it is eaten. Typically, food contaminated with Staphylococcus (such
as salad, meat or sandwiches with mayonnaise) is left un-refrigerated at room
temperature overnight. The Staphylococcal bacteria multiply in the food and
produce toxins. Clostridium perfringens is an example of a bacterium that
multiplies in food (usually canned food), and produces toxins in the small
intestine after the contaminated food is eaten.
Traveler's diarrhea
There are many strains of E. coli bacteria. Most of the E. coli bacteria are normal
inhabitants of the small intestine and colon and are non-pathogenic, meaning
they do not cause disease in the intestines. Nevertheless, these non-pathogenic E. coli
can cause diseases if they spread outside of the intestines, for
example, into the urinary tract (where they cause bladder or kidney infections)
or into the blood stream (sepsis).
Certain strains of E.
coli, however, are pathogenic (meaning they can cause disease in
the small intestine and colon). These pathogenic strains of E. coli
cause diarrhea either by producing toxins (called
enterotoxigenic E.
coli or ETEC) or by invading and inflaming the lining of the small intestine and
the colon and causing enterocolitis (called enteropathogenic E. coli or EPEC).
Traveler's diarrhea usually is caused by an ETEC strain of E. coli that
produces a diarrhea-inducing toxin.
Tourists visiting foreign countries with warm climates and poor sanitation
(Mexico, parts of Africa, etc.) can acquire ETEC by eating contaminated foods
such as fruits, vegetables, seafood, raw meat, water, and ice cubes. Toxins
produced by ETEC cause the sudden onset of diarrhea, abdominal cramps, nausea,
and sometimes vomiting. These symptoms usually occur 3-7 days after arrival in
the foreign country and generally subside within 3 days. Occasionally, other
bacteria or parasites can cause diarrhea in travelers (for example, Shigella,
Giardia,
Campylobacter). Diarrhea caused by these other organisms usually
lasts longer than 3 days.
Bacterial enterocolitis
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) and 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 or 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). Approximately 5% 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.
Parasites
Parasitic infections are not common causes of diarrhea in the U. S. Infection
with Giardia lamblia occurs among individuals who hike in the
mountains or travel abroad and is transmitted by contaminated drinking water.
Infection with Giardia usually is not associated with inflammation; there is no blood or
pus in the stool and little fever. Infection with amoeba (amoebic
dysentery) usually occurs during travel abroad to undeveloped countries and is
associated with signs of inflammation--blood or pus in the stool and fever.
Cryptosporidium is
a diarrhea-producing parasite that is spread by contaminated water because it
can survive chlorination. Cyclospora is a diarrhea-producing parasite that has
been associated with contaminated raspberries from Guatemala.
Drugs
Drug-induced diarrhea is very common because many drugs cause diarrhea. The clue
to drug-induced diarrhea is that the diarrhea begins soon after treatment with the drug is
begun. The medications that most frequently cause diarrhea are antacids and
nutritional supplements that contain magnesium. Other classes of medication that
cause diarrhea include:
A few examples of
specific medications that commonly cause diarrhea are:
Next: What are common causes of chronic diarrhea? »
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