Gastroenteritis or infectious diarrhea is
a medical condition from inflammation of the gastrointestinal tract that involves both
the stomach and the small intestine. It causes some combination of diarrhea, vomiting, and
abdominal pain and cramping. Dehydration may occur as a result. Gastroenteritis has been
referred to as gastro, stomach bug, and stomach virus. Although unrelated to influenza, it
has also been called stomach flu and gastric flu.
Globally, most cases in children are caused by rotavirus. In adults, norovirus and Campylobacter
are more common. Less common causes include other bacteria and parasites. Transmission
may occur due to consumption of improperly prepared foods or contaminated water or via
close contact with individuals who are infectious. Prevention includes the use of fresh water,
regular hand washing, and breast feeding especially in areas where sanitation is less good. The
rotavirus vaccine is recommended for all children. The key treatment is enough fluids. For mild
or moderate cases, this can typically be achieved via oral rehydration solution. In those who
are breast fed, continued breast feeding is recommended. For more severe cases, intravenous
fluids from a healthcare centre may be needed. Antibiotics are generally not recommended.
Gastroenteritis primarily affects children and those in the developing world. It results
in about three to five billion cases and causes 1.4 million deaths a year. Signs and symptoms Gastroenteritis typically involves both diarrhea
and vomiting, or less commonly, presents with only one or the other. Abdominal cramping
may also be present. Signs and symptoms usually begin 12–72 hours after contracting the
infectious agent. If due to a viral agent, the condition usually resolves within one
week. Some viral causes may also be associated with fever, fatigue, headache, and muscle
pain. If the stool is bloody, the cause is less likely to be viral and more likely to
be bacterial. Some bacterial infections may be associated with severe abdominal pain and
may persist for several weeks. Children infected with rotavirus usually make
a full recovery within three to eight days. However, in poor countries treatment for severe
infections is often out of reach and persistent diarrhea is common. Dehydration is a common
complication of diarrhea, and a child with a significant degree of dehydration may have
a prolonged capillary refill, poor skin turgor, and abnormal breathing. Repeat infections
are typically seen in areas with poor sanitation, and malnutrition, stunted growth, and long-term
cognitive delays can result. Reactive arthritis occurs in 1% of people
following infections with Campylobacter species, and Guillain-Barre syndrome occurs in 0.1%.
Hemolytic uremic syndrome may occur due to infection with Shiga toxin-producing Escherichia
coli or Shigella species, causing low platelet counts, poor kidney function, and low red
blood cell count. Children are more predisposed to getting HUS than adults. Some viral infections
may produce benign infantile seizures. Cause
Viruses and the bacteria Escherichia coli and Campylobacter species are the primary
causes of gastroenteritis. There are, however, many other infectious agents that can cause
this syndrome. Non-infectious causes are seen on occasion, but they are less likely than
a viral or bacterial cause. Risk of infection is higher in children due to their lack of
immunity and relatively poor hygiene. Viral
Rotavirus, norovirus, adenovirus, and astrovirus are known to cause viral gastroenteritis.
Rotavirus is the most common cause of gastroenteritis in children, and produces similar rates in
both the developed and developing world. Viruses cause about 70% of episodes of infectious
diarrhea in the pediatric age group. Rotavirus is a less common cause in adults due to acquired
immunity. Norovirus is the cause in about 18% of all cases.
Norovirus is the leading cause of gastroenteritis among adults in America, causing greater than
90% of outbreaks. These localized epidemics typically occur when groups of people spend
time in close physical proximity to each other, such as on cruise ships, in hospitals, or
in restaurants. People may remain infectious even after their diarrhea has ended. Norovirus
is the cause of about 10% of cases in children. Bacterial In the developed world Campylobacter jejuni
is the primary cause of bacterial gastroenteritis, with half of these cases associated with exposure
to poultry. In children, bacteria are the cause in about 15% of cases, with the most
common types being Escherichia coli, Salmonella, Shigella, and Campylobacter species. If food
becomes contaminated with bacteria and remains at room temperature for a period of several
hours, the bacteria multiply and increase the risk of infection in those who consume
the food. Some foods commonly associated with illness include raw or undercooked meat, poultry,
seafood, and eggs; raw sprouts; unpasteurized milk and soft cheeses; and fruit and vegetable
juices. In the developing world, especially sub-Saharan Africa and Asia, cholera is a
common cause of gastroenteritis. This infection is usually transmitted by contaminated water
or food. Toxigenic Clostridium difficile is an important
cause of diarrhea that occurs more often in the elderly. Infants can carry these bacteria
without developing symptoms. It is a common cause of diarrhea in those who are hospitalized
and is frequently associated with antibiotic use. Staphylococcus aureus infectious diarrhea
may also occur in those who have used antibiotics. “Traveler’s diarrhea” is usually a type of
bacterial gastroenteritis. Acid-suppressing medication appears to increase the risk of
significant infection after exposure to a number of organisms, including Clostridium
difficile, Salmonella, and Campylobacter species. The risk is greater in those taking proton
pump inhibitors than with H2 antagonists. Parasitic
A number of protozoans can cause gastroenteritis – most commonly Giardia lamblia – but
Entamoeba histolytica and Cryptosporidium species have also been implicated. As a group,
these agents comprise about 10% of cases in children. Giardia occurs more commonly in
the developing world, but this etiologic agent causes this type of illness to some degree
nearly everywhere. It occurs more commonly in persons who have traveled to areas with
high prevalence, children who attend day care, men who have sex with men, and following disasters.
Transmission Transmission may occur via consumption of
contaminated water, or when people share personal objects. In places with wet and dry seasons,
water quality typically worsens during the wet season, and this correlates with the time
of outbreaks. In areas of the world with four seasons, infections are more common in the
winter. Bottle-feeding of babies with improperly sanitized bottles is a significant cause on
a global scale. Transmission rates are also related to poor hygiene, especially among
children, in crowded households, and in those with pre-existing poor nutritional status.
After developing tolerance, adults may carry certain organisms without exhibiting signs
or symptoms, and thus act as natural reservoirs of contagion. While some agents only occur
in primates, others may occur in a wide variety of animals.
Non-infectious There are a number of non-infectious causes
of inflammation of the gastrointestinal tract. Some of the more common include medications,
certain foods such as lactose, and gluten. Crohn’s disease is also a non-infection source
of gastroenteritis. Disease secondary to toxins may also occur. Some food related conditions
associated with nausea, vomiting, and diarrhea include: ciguatera poisoning due to consumption
of contaminated predatory fish, scombroid associated with the consumption of certain
types of spoiled fish, tetrodotoxin poisoning from the consumption of puffer fish among
others, and botulism typically due to improperly preserved food.
Pathophysiology Gastroenteritis is defined as vomiting or
diarrhea due to infection of the small or large bowel. The changes in the small bowel
are typically noninflammatory, while the ones in the large bowel are inflammatory. The number
of pathogens required to cause an infection varies from as few as one to as many as 108.
Diagnosis Gastroenteritis is typically diagnosed clinically,
based on a person’s signs and symptoms. Determining the exact cause is usually not needed as it
does not alter management of the condition. However, stool cultures should be performed
in those with blood in the stool, those who might have been exposed to food poisoning,
and those who have recently traveled to the developing world. Diagnostic testing may also
be done for surveillance. As hypoglycemia occurs in approximately 10% of infants and
young children, measuring serum glucose in this population is recommended. Electrolytes
and kidney function should also be checked when there is a concern about severe dehydration.
Dehydration A determination of whether or not the person
has dehydration is an important part of the assessment, with dehydration typically divided
into mild, moderate, and severe cases. In children, the most accurate signs of moderate
or severe dehydration are a prolonged capillary refill, poor skin turgor, and abnormal breathing.
Other useful findings include sunken eyes, decreased activity, a lack of tears, and a
dry mouth. A normal urinary output and oral fluid intake is reassuring. Laboratory testing
is of little clinical benefit in determining the degree of dehydration.
Differential diagnosis Other potential causes of signs and symptoms
that mimic those seen in gastroenteritis that need to be ruled out include appendicitis,
volvulus, inflammatory bowel disease, urinary tract infections, and diabetes mellitus. Pancreatic
insufficiency, short bowel syndrome, Whipple’s disease, coeliac disease, and laxative abuse
should also be considered. The differential diagnosis can be complicated somewhat if the
person exhibits only vomiting or diarrhea. Appendicitis may present with vomiting, abdominal
pain, and a small amount of diarrhea in up to 33% of cases. This is in contrast to the
large amount of diarrhea that is typical of gastroenteritis. Infections of the lungs or
urinary tract in children may also cause vomiting or diarrhea. Classical diabetic ketoacidosis
presents with abdominal pain, nausea, and vomiting, but without diarrhea. One study
found that 17% of children with DKA were initially diagnosed as having gastroenteritis.
A supply of easily accessible uncontaminated water and good sanitation practices are important
for reducing rates of infection and clinically significant gastroenteritis. Personal measures
have been found to decrease incidence and prevalence rates of gastroenteritis in both
the developing and developed world by as much as 30%. Alcohol-based gels may also be effective.
Breastfeeding is important, especially in places with poor hygiene, as is improvement
of hygiene generally. Breast milk reduces both the frequency of infections and their
duration. Avoiding contaminated food or drink should also be effective.
Vaccination Due to both its effectiveness and safety,
in 2009 the World Health Organization recommended that the rotavirus vaccine be offered to all
children globally. Two commercial rotavirus vaccines exist and several more are in development.
In Africa and Asia these vaccines reduced severe disease among infants and countries
that have put in place national immunization programs have seen a decline in the rates
and severity of disease. This vaccine may also prevent illness in non-vaccinated children
by reducing the number of circulating infections. Since 2000, the implementation of a rotavirus
vaccination program in the United States has substantially decreased the number of cases
of diarrhea by as much as 80 percent. The first dose of vaccine should be given to infants
between 6 and 15 weeks of age. The oral cholera vaccine has been found to be 50–60% effective
over 2 years. Management
Gastroenteritis is usually an acute and self-limiting disease that does not require medication.
The preferred treatment in those with mild to moderate dehydration is oral rehydration
therapy. Metoclopramide and/or ondansetron, however, may be helpful in some children,
and butylscopolamine is useful in treating abdominal pain.
Rehydration The primary treatment of gastroenteritis in
both children and adults is rehydration. This is preferably achieved by oral rehydration
therapy, although intravenous delivery may be required if there is a decreased level
of consciousness or if dehydration is severe. Oral replacement therapy products made with
complex carbohydrates may be superior to those based on simple sugars. Drinks especially
high in simple sugars, such as soft drinks and fruit juices, are not recommended in children
under 5 years of age as they may increase diarrhea. Plain water may be used if more
specific and effective ORT preparations are unavailable or are not palatable. A nasogastric
tube can be used in young children to administer fluids if warranted.
Dietary It is recommended that breast-fed infants
continue to be nursed in the usual fashion, and that formula-fed infants continue their
formula immediately after rehydration with ORT. Lactose-free or lactose-reduced formulas
usually are not necessary. Children should continue their usual diet during episodes
of diarrhea with the exception that foods high in simple sugars should be avoided. The
BRAT diet is no longer recommended, as it contains insufficient nutrients and has no
benefit over normal feeding. Some probiotics have been shown to be beneficial in reducing
both the duration of illness and the frequency of stools. They may also be useful in preventing
and treating antibiotic associated diarrhea. Fermented milk products are similarly beneficial.
Zinc supplementation appears to be effective in both treating and preventing diarrhea among
children in the developing world. Antiemetics
Antiemetic medications may be helpful for treating vomiting in children. Ondansetron
has some utility, with a single dose being associated with less need for intravenous
fluids, fewer hospitalizations, and decreased vomiting. Metoclopramide might also be helpful.
However, the use of ondansetron might possibly be linked to an increased rate of return to
hospital in children. The intravenous preparation of ondansetron may be given orally if clinical
judgment warrants. Dimenhydrinate, while reducing vomiting, does not appear to have a significant
clinical benefit. Antibiotics
Antibiotics are not usually used for gastroenteritis, although they are sometimes recommended if
symptoms are particularly severe or if a susceptible bacterial cause is isolated or suspected.
If antibiotics are to be employed, a macrolide is preferred over a fluoroquinolone due to
higher rates of resistance to the latter. Pseudomembranous colitis, usually caused by
antibiotic use, is managed by discontinuing the causative agent and treating it with either
metronidazole or vancomycin. Bacteria and protozoans that are amenable to treatment
include Shigella Salmonella typhi, and Giardia species. In those with Giardia species or
Entamoeba histolytica, tinidazole treatment is recommended and superior to metronidazole.
The World Health Organization recommends the use of antibiotics in young children who have
both bloody diarrhea and fever. Antimotility agents
Antimotility medication has a theoretical risk of causing complications, and although
clinical experience has shown this to be unlikely, these drugs are discouraged in people with
bloody diarrhea or diarrhea that is complicated by fever. Loperamide, an opioid analogue,
is commonly used for the symptomatic treatment of diarrhea. Loperamide is not recommended
in children, however, as it may cross the immature blood–brain barrier and cause toxicity.
Bismuth subsalicylate, an insoluble complex of trivalent bismuth and salicylate, can be
used in mild to moderate cases, but salicylate toxicity is theoretically possible.
Epidemiology It is estimated that three to five billion
cases of gastroenteritis resulting in 1.4 million deaths occur globally on an annual basis,
with children and those in the developing world being primarily affected. As of 2011,
in those less than five, there were about 1.7 billion cases resulting in 0.7 million
deaths, with most of these occurring in the world’s poorest nations. More than 450,000
of these fatalities are due to rotavirus in children under 5 years of age. Cholera causes
about three to five million cases of disease and kills approximately 100,000 people yearly.
In the developing world children less than two years of age frequently get six or more
infections a year that result in clinically significant gastroenteritis. It is less common
in adults, partly due to the development of acquired immunity.
In 1980, gastroenteritis from all causes caused 4.6 million deaths in children, with the majority
occurring in the developing world. Death rates were reduced significantly by the year 2000,
largely due to the introduction and widespread use of oral rehydration therapy. In the US,
infections causing gastroenteritis are the second most common infection, and they result
in between 200 and 375 million cases of acute diarrhea and approximately ten thousand deaths
annually, with 150 to 300 of these deaths in children less than five years of age.
History The first usage of “gastroenteritis” was in
1825. Before this time it was more specifically known as typhoid fever or “cholera morbus”,
among others, or less specifically as “griping of the guts”, “surfeit”, “flux”, “colic”,
“bowel complaint”, or any one of a number of other archaic names for acute diarrhea.
Society and culture Gastroenteritis is associated with many colloquial
names, including “Montezuma’s revenge”, “Delhi belly”, “la turista”, and “back door sprint”,
among others. It has played a role in many military campaigns and is believed to be the
origin of the term “no guts no glory”. Gastroenteritis is the main reason for 3.7 million
visits to physicians a year in the United States and 3 million visits in France. In
the United States gastroenteritis as a whole is believed to result in costs of 23 billion
USD per year with that due to rotavirus alone resulting in estimated costs of 1 billion
USD a year. Research
There are a number of vaccines against gastroenteritis in development. For example, vaccines against
Shigella and enterotoxigenic Escherichia coli, two of the leading bacterial causes of gastroenteritis
worldwide. Other animals
Many of the same agents cause gastroenteritis in cats and dogs as in humans. The most common
organisms are Campylobacter, Clostridium difficile, Clostridium perfringens, and Salmonella. A
large number of toxic plants may also cause symptoms.
Some agents are more specific to a certain species. Transmissible gastroenteritis coronavirus
occurs in pigs resulting in vomiting, diarrhea, and dehydration. It is believed to be introduced
to pigs by wild birds and there is no specific treatment available. It is not transmissible
to humans. References Notes
Dolin, [edited by] Gerald L. Mandell, John E. Bennett, Raphael. Mandell, Douglas, and
Bennett’s principles and practice of infectious diseases. Philadelphia, PA: Churchill Livingstone/Elsevier.
ISBN 0-443-06839-9. External links
Gastroenteritis at DMOZ Diarrhoea and Vomiting Caused by Gastroenteritis:
Diagnosis, Assessment and Management in Children Younger than 5 Years – NICE Clinical Guidelines,