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Gastroenteritis Microchapters

Patient Information



Differential Diagnosis


Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1];Associate Editor(s)-in-Chief: Seyedmahdi Pahlavani, M.D. [2]


Acute gastroenteritis and diarrhea are among the leading causes of seeking medical care. Approximately, 48 million cases occur annually that cost about $150 million for the U.S. health care system. [1][2] Gastroenteritis is defined as inflammation of the stomach or intestinal mucosa. It typically presents with acute diarrhea, fever, nausea and vomiting, anorexia and crampy abdominal pain and is defined as passage of loose stool for at least 3 times per day for less than 14 days. It may be caused by viruses, bacteria or parasites. Most cases of acute gastroenteritis are caused by viruses and among them, norovirus (norwalk virus) is the most common etiology for adults.[3][4][5] Other common viral causes include, Rotavirus, Adenovirus and Astrovirus. Common bacterial causes of gastroenteritis include, Escherichia coli sp, Salmonella sp, Yersinia enterocolitica and Vibrio sp that can cause watery diarrhea and Shigella sp and Campylobacter sp that can cause dysenteric diarrhea. Parasites are other causes of gastroenteritis especially in developing countries which Giardia lamblia and Entamoeba histolytica are the most frequent causes. First step in management of this patients is to evaluate the hydration status and vital signs. Once the patient is stabilized, health care provider must proceed to diagnostic evaluation. There are some principles to decrease the risk of acquiring infection which include, using safe water and foods, avoid unsafe foods during traveling and hand washing.


Abbreviations: ETEC: Enterotoxigenic Escherichia coli, EPEC: Enteropathogenic Escherichia coli, EHEC: Enterohemorrhagic Escherichia coli, EAEC: Enteroaggregative Escherichia coli, EIEC: Enteroinvasive Escherichia coli, SARS: severe acute respiratory syndrome

Less Common
Less Common
(including SARS)
Parvovirus •Kobuviruses
Orthoreovirus •Torovirus
Gram Positive
Gram Negative
Gram Positive
Gram Negative
Trichinella spiralis
Trichuris trichiura
Strongyloides stercoralis
Taenia solium
Taenia saginata
Diphyllobothrium latum
Schistosoma mansoni
Giardia lamblia
Entamoeba histolytica
Cryptosporidium parvum
Cyclospora cayetanensis
Clostridium perfringens
Clostridium difficile
Bloody diarrhea (dysentery)
Watery diarrhea
Bacillus cereus

Listeria monocytogenes
Mycobacterium sp*.

Clostridium botulinum
Bacteroides fragilis
Aeromonas hydrophila
Campylobacter sp.

Shigella sp.Escherichia coli (EHEC, EIEC)

Salmonella(non-typhoidal) sp.
Escherichia coli

Salmonella(typhoidal) sp.
Yersinia enterocolitica

Vibrio sp.

§ EHEC, EIEC, EPEC and EAEC may cause bloody diarrhea, but they are classically associated with watery diarrhea.
† Both Salmonella and Yersinia can cause watery and or bloody diarrhea.
Entamoeba histolytica may cause dysentery.

* Mycobacterium sp is Gram Postive Acid fast.

Differential Diagnosis

Organism Age predilection Travel History Incubation Size (cell) Incubation Time History and Symptoms Diarrhea type∞ Food source Specific consideration
Fever N/V Cramping Abd Pain Small Bowel Large Bowel Inflammatory Non-inflammatory
Viral Rotavirus <2 y - <102 <48 h + + - + + - Most common cause of diarrhea among children[6].

Mostly in day cares and in winter.

Norovirus Any age - 10 -103 24-48 h + + + + + - Most common cause of adult gastroenteritis.

Common infection on cruise ships.

Adenovirus <2 y - 105 -106 8-10 d + + + + + - Associated with multiorgan involvement.

No seasonality.

Astrovirus <5 y - 72-96 h + + + + + Seafood Mostly during winter
Bacterial Escherichia coli ETEC Any age + 108 -1010 24 h - + + + + - Causes traveler's diarrhea.

Contains heat-labile toxins (LT) and heat-stable toxins (ST).

EPEC <1 y - 10 6-12 h - + + + + Raw beef and chicken Mostly affects pediatric population.
EIEC Any ages - 10 24 h + + + + + Hamburger meat and unpasteurized milk Similar to shigellosis, can cause bloody diarrhea.


Any ages - 10 3-4 d - + + + + Undercooked or raw hamburger (ground beef)  Can cause HUS/TTP.

Prescribing antibiotics may worsen the condition.

EAEC Any ages + 1010 8-18 h - - + + + - May cause prolonged or persistent diarrhea in children
Salmonella sp. Any ages + 1 6 to 72 h + + + + + Meats, poultry, eggs, milk and dairy products, fish, shrimp, spices, yeast, coconut, sauces, freshly prepared salad. Can cause salmonellosis or typhoid fever.
Shigella sp. Any ages - 10 - 200 8-48 h + + + + + Raw foods, for example, lettuce, salads (potato, tuna, shrimp, macaroni, and chicken) Some strains produce enterotoxin and Shiga toxin similar to those produced by E. coli O157:H7
Campylobacter sp. <5 y, 15-29 y - 104 2-5 d + + + + + Undercooked poultry products, unpasteurized milk and cheeses made from unpasteurized milk, vegetables, seafood and contaminated water. May cause bacteremia, Guillain-Barré syndrome (GBS), hemolytic uremic syndrome (HUS) and recurrent colitis
Yersinia enterocolitica <10 y - 104 -106 1-11 d + + + + + Meats (pork, beef, lamb, etc.), oysters, fish, crabs, and raw milk. Causes Pseudo-Appendicitis (due to mesenteric adenitis / granulomatous microabscesses).

Also cause reactive arthritis, glomerulonephritis, endocarditis, and erythema nodosum.

Clostridium perfringens Any ages > 106 16 h - - + + + Meats (especially beef and poultry), meat-containing products (e.g., gravies and stews), and Mexican foods. Can survive high heat.

Also causes gas gangrene.

Vibrio cholerae Any ages - 106-1010 24-48 h - + + + + Seafoods, including molluscan shellfish (oysters, mussels, and clams), crab, lobster, shrimp, squid, and finfish. Endemic to developing countries.

Typical rice-water stools.

Parasites Protozoa Giardia lamblia 2-5 y + 1 cyst 1-2 we - - + + + Contaminated water (chlorination does not kill the cysts) May cause malabsorption syndrome leading to severe weight loss.
Entamoeba histolytica 4-11 y + <10 cysts 2-4 we - + + + + Contaminated water and raw foods May cause intestinal amoebiasis and amoebic liver abscess with characteristic ''Anchovy paste'' abscess.
Cryptosporidium parvum Any ages - 10-100 oocysts 7-10 d + + + + + Juices and milk Most common cause of diarrhea in AIDS patients( especially with CD4 < 180).
Cyclospora cayetanensis Any ages + 10-100 oocysts 7-10 d - + + + + Fresh produce, such as raspberries, basil, and several varieties of lettuce. More common in rainy areas
Helminths Trichinella spp Any ages - Two viable larvae (male and female) 1-4 we - + + + + Undercooked meats More common in hunters or people who eat traditionally uncooked meats
Taenia spp Any ages - 1 larva or egg 2-4 m - + + + + Undercooked beef and pork Neurocysticercosis: Cysts located in the brain may be asymptomatic or seizures, increased intracranial pressure, headache.
Diphyllobothrium latum Any ages - 1 larva 15 d - - - + + Raw or undercooked fish. May cause vitamin B12 deficiency

Small bowel diarrhea: watery, voluminous with less than 5 WBC/high power field

Large bowel diarrhea: Mucousy and/or bloody with less volume and more than 10 WBC/high power field
† It could be as high as 1000 based on patient's immunity system.


Non travel setting

  • Contaminated foods are major causes of foodborne illness in the United states.[1][2]
  • To prevent food preparation chain from contamination, every steps of this process including, products in the farms, packaging industries, stores, restaurants and individuals in the home who are buying and preparing food must be take in to consideration.
  • Proper maintaining the filtration systems at water plants is also essential.
  • Avoid consuming unpasteurized milk or soft cheeses.
  • Wash your hands frequently and effectively and use alcohol-based hand sanitizers.
  • Rotavirus vaccination is recommended for all infants unless there is a contraindication for it.[7]

Travel setting

  • A simple rule is, boil it, cook it, peel it, or forget it!
  • Use bottled water or boil all drinking water while on outdoor adventures.
  • Wash your hands frequently and effectively and use alcohol-based hand sanitizers especially during cruise traveling.
  • Chemoprophylaxis with Bismuth subsalicylate (BSS) has been shown to reduce the frequency of traveler's diarrhea (TD) when used during period of risk for 3 weeks.[8] The recommended dose of BSS for TD prevention is two tablets four daily doses at mealtimes and at bedtime. BSS could be used for trips up to 2 weeks.[9]
  • Offer the typhoid vaccine to travelers going to countries with high prevalence of typhoid fever.


  1. 1.0 1.1 Scallan E, Griffin PM, Angulo FJ, Tauxe RV, Hoekstra RM (2011). "Foodborne illness acquired in the United States--unspecified agents". Emerging Infect. Dis. 17 (1): 16–22. doi:10.3201/eid1701.091101p2. PMC 3204615. PMID 21192849.
  2. 2.0 2.1 Scallan E, Hoekstra RM, Angulo FJ, Tauxe RV, Widdowson MA, Roy SL, Jones JL, Griffin PM (2011). "Foodborne illness acquired in the United States--major pathogens". Emerging Infect. Dis. 17 (1): 7–15. doi:10.3201/eid1701.091101p1. PMC 3375761. PMID 21192848.
  3. Bresee JS, Marcus R, Venezia RA, Keene WE, Morse D, Thanassi M, Brunett P, Bulens S, Beard RS, Dauphin LA, Slutsker L, Bopp C, Eberhard M, Hall A, Vinje J, Monroe SS, Glass RI (2012). "The etiology of severe acute gastroenteritis among adults visiting emergency departments in the United States". J. Infect. Dis. 205 (9): 1374–81. doi:10.1093/infdis/jis206. PMID 22454468.
  4. Hall AJ, Rosenthal M, Gregoricus N, Greene SA, Ferguson J, Henao OL, Vinjé J, Lopman BA, Parashar UD, Widdowson MA (2011). "Incidence of acute gastroenteritis and role of norovirus, Georgia, USA, 2004-2005". Emerging Infect. Dis. 17 (8): 1381–8. doi:10.3201/eid1708.101533. PMC 3381564. PMID 21801613.
  5. Wikswo ME, Hall AJ (2012). "Outbreaks of acute gastroenteritis transmitted by person-to-person contact--United States, 2009-2010". MMWR Surveill Summ. 61 (9): 1–12. PMID 23235338.
  6. Elliott EJ (2007). "Acute gastroenteritis in children". BMJ. 334 (7583): 35–40. doi:10.1136/bmj.39036.406169.80. PMC 1764079. PMID 17204802.
  7. Cortese MM, Parashar UD (2009). "Prevention of rotavirus gastroenteritis among infants and children: recommendations of the Advisory Committee on Immunization Practices (ACIP)". MMWR Recomm Rep. 58 (RR-2): 1–25. PMID 19194371.
  8. DuPont HL, Sullivan P, Evans DG, Pickering LK, Evans DJ, Vollet JJ, Ericsson CD, Ackerman PB, Tjoa WS (1980). "Prevention of traveler's diarrhea (emporiatric enteritis). Prophylactic administration of subsalicylate bismuth)". JAMA. 243 (3): 237–41. PMID 6985681.
  9. DuPont HL, Ericsson CD, Farthing MJ, Gorbach S, Pickering LK, Rombo L, Steffen R, Weinke T (2009). "Expert review of the evidence base for prevention of travelers' diarrhea". J Travel Med. 16 (3): 149–60. doi:10.1111/j.1708-8305.2008.00299.x. PMID 19538575.