See also Gastroenteritis

Gastroenteritis

Gastroenteritis is marked by severe inflammation of the gastrointestinal tract involving both the stomach and small intestine resulting in acute diarrhea and vomiting. It can be transferred by contact with contaminated food and water...

 and Enteritis

Enteritis

In medicine, enteritis, from Greek words enteron and suffix -itis , refers to inflammation of the small intestine. It is most commonly caused by the ingestion of substances contaminated with pathogenic microorganisms. Symptoms include abdominal pain, cramping, diarrhea, dehydration and fever...

Infectious diarrhea or Contagious diarrhea may be defined as diarrhea

Diarrhea

Diarrhea , also spelled diarrhoea, is the condition of having three or more loose or liquid bowel movements per day. It is a common cause of death in developing countries and the second most common cause of infant deaths worldwide. The loss of fluids through diarrhea can cause dehydration and...

 caused by an infection of the digestive system by a bacterium

Bacteria

Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

, virus

Virus

A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...

, or parasite that results in frequent bowel motions producing excessive amounts of liquidy feces.

Causes

This can usually be presumed to be infective, although only in a minority of cases is this formally proven.

Virus

The diarrhea is usually viral in origin, and is mostly caused by Norovirus, Rotavirus

Rotavirus

Rotavirus is the most common cause of severe diarrhoea among infants and young children, and is one of several viruses that cause infections often called stomach flu, despite having no relation to influenza. It is a genus of double-stranded RNA virus in the family Reoviridae. By the age of five,...

, Adenovirus, or Astrovirus

Astrovirus

Astrovirus is a type of virus that was first discovered in 1975 using electron microscopes following an outbreak of diarrhoea in humans. In addition to humans, astroviruses have now been isolated from numerous mammalian animal species and from avian species such as ducks, chickens, and turkey...

.

Virus

Virus

A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...

es, particularly rotavirus

Rotavirus

Rotavirus is the most common cause of severe diarrhoea among infants and young children, and is one of several viruses that cause infections often called stomach flu, despite having no relation to influenza. It is a genus of double-stranded RNA virus in the family Reoviridae. By the age of five,...

, are common in children. (Viral diarrhea is probably over-diagnosed by non-doctors). Norwalk virus (i.e. norovirus) can also cause these symptoms.

Bacteria and their toxins

Common organisms include Campylobacter jejuni

Campylobacter jejuni

Campylobacter jejuni is a species of curved, helical-shaped, non-spore forming, Gram-negative, microaerophilic bacteria commonly found in animal feces. It is one of the most common causes of human gastroenteritis in the world. Food poisoning caused by Campylobacter species can be severely...

and Salmonella

Salmonella

Salmonella is a genus of rod-shaped, Gram-negative, non-spore-forming, predominantly motile enterobacteria with diameters around 0.7 to 1.5 µm, lengths from 2 to 5 µm, and flagella which grade in all directions . They are chemoorganotrophs, obtaining their energy from oxidation and reduction...

, both typically acquired from animal food products. Often "food poisoning" is really Salmonella infection.

Shigella

Shigella

Shigella is a genus of Gram-negative, nonspore forming, non-motile, rod-shaped bacteria closely related to Escherichia coli and Salmonella. The causative agent of human shigellosis, Shigella causes disease in primates, but not in other mammals. It is only naturally found in humans and apes. During...

dysentery is less common, and usually human in origin.

Vibrio cholerae

Vibrio cholerae

Vibrio cholerae is a Gram-negative, comma-shaped bacterium. Some strains of V. cholerae cause the disease cholera. V. cholerae is facultatively anaerobic and has a flagella at one cell pole. V...

/Cholera

Cholera

Cholera is an infection of the small intestine that is caused by the bacterium Vibrio cholerae. The main symptoms are profuse watery diarrhea and vomiting. Transmission occurs primarily by drinking or eating water or food that has been contaminated by the diarrhea of an infected person or the feces...

 is rare in Western countries. It is more common in travelers and is usually related to contaminated water (its ultimate source is probably sea water).

Vibrio parahaemolyticus

Vibrio parahaemolyticus

Vibrio parahaemolyticus is a curved, rod-shaped, Gram-negative bacterium found in brackish saltwater, which, when ingested, causes gastrointestinal illness in humans. V. parahaemolyticus is oxidase positive, facultatively aerobic, and does not form spores...

can be found in seafood.

Escherichia coli

Escherichia coli

Escherichia coli is a Gram-negative, rod-shaped bacterium that is commonly found in the lower intestine of warm-blooded organisms . Most E. coli strains are harmless, but some serotypes can cause serious food poisoning in humans, and are occasionally responsible for product recalls...

is a very common cause of diarrhea, especially traveler's diarrhea

Traveler's diarrhea

Traveler's diarrhea , is the most common illness affecting travelers. An estimated 10 million people—20% to 50% of international travelers—develop it annually. TD is defined as three or more unformed stools in 24 hours passed by a traveler, commonly accompanied by abdominal cramps, nausea, and...

, but it can be difficult to detect using current technology. The types of E. coli vary from area to area and country to country.

Clostridium difficile

Clostridium difficile

Clostridium difficile , also known as "CDF/cdf", or "C...

is considered the most common cause of infectious diarrhea in hospitalized patients worldwide.

Toxins and food poisoning can cause diarrhea. These include staphylococcal

Staphylococcus

Staphylococcus is a genus of Gram-positive bacteria. Under the microscope they appear round , and form in grape-like clusters....

 toxin (often from milk products due to an infected wound in workers), and Bacillus cereus

Bacillus cereus

Bacillus cereus is an endemic, soil-dwelling, Gram-positive, rod-shaped, beta hemolytic bacterium. Some strains are harmful to humans and cause foodborne illness, while other strains can be beneficial as probiotics for animals...

.

Brachyspira pilosicoli

Brachyspira pilosicoli

Brachyspira pilosicoli is a gram-negative spiral-shaped obligate anaerobe bacterium. It is a member of the Spirochaetes family. The bacterium is loosely coiled and is 6-11µm long. It has several flagellae, inserted at either pole of the cell, and a lipopolysaccharide cell wall. It causes intestinal...

and Brachyspira aalborgi are rare causes diarrhea seen in the context of male homosexuality.

Worms

Worms sometimes cause diarrhea but are often accompanied by weight loss, irritability, rash

Rash

A rash is a change of the skin which affects its color, appearance or texture. A rash may be localized in one part of the body, or affect all the skin. Rashes may cause the skin to change color, itch, become warm, bumpy, chapped, dry, cracked or blistered, swell and may be painful. The causes, and...

es or anal itching. The most common is pinworm

Pinworm

The pinworm , also known as threadworm or seatworm, is a nematode and a common human intestinal parasite, especially in children...

 (mostly a nuisance rather than a severe medical illness). Other worms, such as hookworm

Hookworm

The hookworm is a parasitic nematode that lives in the small intestine of its host, which may be a mammal such as a dog, cat, or human. Two species of hookworms commonly infect humans, Ancylostoma duodenale and Necator americanus. A. duodenale predominates in the Middle East, North Africa, India...

, ascaria, and tapeworm are more medically significant and may cause weight loss, anemia, general unwellness and allergy problems.

Other

Giardia lamblia

Giardia lamblia

Giardia lamblia is a flagellated protozoan parasite that colonizes and reproduces in the small intestine, causing giardiasis. The giardia parasite attaches to the epithelium by a ventral adhesive disc, and reproduces via binary fission...

is a common cause.

Amoebic dysentery

Amoebic dysentery

Amoebic dysentery is a type of dysentery caused primarily by the amoeba Entamoeba histolytica. Amoebic dysentery is transmitted through contaminated food and water. Amoebae spread by forming infective cysts which can be found in stools, and spread if whoever touches them does not sanitize their...

 due to Entamoeba histolytica

Entamoeba histolytica

Entamoeba histolytica is an anaerobic parasitic protozoan, part of the genus Entamoeba. Predominantly infecting humans and other primates, E. histolytica is estimated to infect about 50 million people worldwide...

is an important cause of bloody diarrhea in travelers and also sometimes in western countries.

Another cause is Cryptosporidium

Cryptosporidium

Cryptosporidium is a protozoan that can cause gastro-intestinal illness with diarrhea in humans.Cryptosporidium is the organism most commonly isolated in HIV positive patients presenting with diarrhea...

, acquired via fecally contaminated food or water.

Prevention

A rotavirus vaccine has between 2000 and 2009 decreased the number of cases of diarrhea due to rotavirus in the United States.

Diagnosis

In more severe cases, or where it is important to find the cause of the illness, stool cultures are instituted.

Among medical inpatients, the presence of fecal leukocytes can predict a "breach in the colonic mucosa (any infectious or inflammatory condition, blood in the stool, or acute vascular insufficiency)":

• sensitivity = 28%
• specificity = 92%

Treatment

The first priority in treatment of acute diarrhea is ensuring that patients are adequately rehydrated, as significant amounts of fluid may be lost. This fluid loss is the primary mechanism of mortality from acute diarrhea in patients. In moderate to severe cases of acute diarrhea this is often accomplished with saline

Saline (medicine)

In medicine, saline is a general term referring to a sterile solution of sodium chloride in water but is only sterile when it is to be placed intravenously, otherwise, a saline solution is a salt water solution...

 or another appropriate solution given through an IV line. With mild cases of acute diarrhea, it is often reasonable to reassure a patient, ensure adequate fluid intake, and wait and see. For children in the developing world, the World Health Organization

World Health Organization

The World Health Organization is a specialized agency of the United Nations that acts as a coordinating authority on international public health. Established on 7 April 1948, with headquarters in Geneva, Switzerland, the agency inherited the mandate and resources of its predecessor, the Health...

 recommends the use of oral rehydration solution and zinc

Zinc

Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...

 supplementation for treatment of diarrhea.

Parasites (worms and amoeba) should always be treated with antimicrobial

Antimicrobial

An anti-microbial is a substance that kills or inhibits the growth of microorganisms such as bacteria, fungi, or protozoans. Antimicrobial drugs either kill microbes or prevent the growth of microbes...

 drugs.

Antimotility agents

Loperamide can reduce diarrhea in patients with shigella

Shigella

Shigella is a genus of Gram-negative, nonspore forming, non-motile, rod-shaped bacteria closely related to Escherichia coli and Salmonella. The causative agent of human shigellosis, Shigella causes disease in primates, but not in other mammals. It is only naturally found in humans and apes. During...

, but not in patients with traveler's diarrhea

Traveler's diarrhea

Traveler's diarrhea , is the most common illness affecting travelers. An estimated 10 million people—20% to 50% of international travelers—develop it annually. TD is defined as three or more unformed stools in 24 hours passed by a traveler, commonly accompanied by abdominal cramps, nausea, and...

 due to enterotoxigenic E. coli.

A systematic review

Systematic review

A systematic review is a literature review focused on a research question that tries to identify, appraise, select and synthesize all high quality research evidence relevant to that question. Systematic reviews of high-quality randomized controlled trials are crucial to evidence-based medicine...

 of randomized controlled trials found that loperamide

Loperamide

Loperamide , a synthetic piperidine derivative, is an opioid drug used against diarrhea resulting from gastroenteritis or inflammatory bowel disease. In most countries it is available generically and under brand names such as Lopex, Imodium, Dimor, Fortasec, and Pepto Diarrhea Control...

 may harm children less than 3 years old.

Antisecretory agents

A randomized controlled trial

Randomized controlled trial

A randomized controlled trial is a type of scientific experiment - a form of clinical trial - most commonly used in testing the safety and efficacy or effectiveness of healthcare services or health technologies A randomized controlled trial (RCT) is a type of scientific experiment - a form of...

 found that racecadotril

Racecadotril

Racecadotril, also known as acetorphan, is an antidiarrheal drug which acts as a peripherally acting enkephalinase inhibitor. Unlike other medications used to treat diarrhea, which reduce intestinal motility, racecadotril has an antisecretory effect—it reduces the secretion of water and...

, an enkephalinase

Enkephalinase

Enkephalinases are enzymes which degrade endogenous enkephalin opioid peptides. They include:* Aminopeptidase N * Neutral endopeptidase * Dipeptidyl peptidase 3 * Carboxypeptidase A6 * Angiotensin-converting enzyme...

 inhibitor, may reduce the volume of watery diarrhea.

Antibiotics

Norfloxacin

Norfloxacin

Norfloxacin is a synthetic chemotherapeutic antibacterial agent occasionally used to treat common as well as complicated urinary tract infections. It is sold under various brand names with the most common being Noroxin. In form of ophthalmic solutions it is known as Chibroxin...

 can reduce the duration of acute diarrhea due to bacterial pathogens. However, norfloxacin

Norfloxacin

Norfloxacin is a synthetic chemotherapeutic antibacterial agent occasionally used to treat common as well as complicated urinary tract infections. It is sold under various brand names with the most common being Noroxin. In form of ophthalmic solutions it is known as Chibroxin...

 may prolong infectivity of patients with salmonella

Salmonella

Salmonella is a genus of rod-shaped, Gram-negative, non-spore-forming, predominantly motile enterobacteria with diameters around 0.7 to 1.5 µm, lengths from 2 to 5 µm, and flagella which grade in all directions . They are chemoorganotrophs, obtaining their energy from oxidation and reduction...

 and cause resistant campylobacter

Campylobacter

Campylobacter is a genus of bacteria that are Gram-negative, spiral, and microaerophilic. Motile, with either unipolar or bipolar flagella, the organisms have a characteristic spiral/corkscrew appearance and are oxidase-positive. Campylobacter jejuni is now recognized as one of the main causes...

.

Prognosis

Acute infectious diarrhea usually lasts 7 days when not treated with antibiotics. It is not uncommon for diarrhea to persist. Diarrhea due to some organisms may persist for years without significant long term illness. More commonly the diarrhea slowly ameliorates but the patient becomes a carrier (harbors the infection without illness). This is often an indication for treatment, especially in food workers or institution workers. In the developing world, infectious diarrhea is a serious, life-threatening illness that results in 4 to 6 million deaths each year, mostly in children.

Salmonella

Salmonella

Salmonella is a genus of rod-shaped, Gram-negative, non-spore-forming, predominantly motile enterobacteria with diameters around 0.7 to 1.5 µm, lengths from 2 to 5 µm, and flagella which grade in all directions . They are chemoorganotrophs, obtaining their energy from oxidation and reduction...

is the most common persistent bacterial organism in humans.

See also

• Wilderness diarrhea