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Gastroenteritis involves diarrhea or vomitting, with noninflammatory infection of the upper small bowel, or inflammatory infection of the colon, both part of the gastrointestinal tract. Sleisenger & Fordtran's Gastrointestinal and Liver Disease 7th edition, 2-Volume Set, By Mark Feldman, MD, Chair of Internal Medicine, Presbyterian Hospital of Dallas, Clinical Professor of Internal Medicine, University of Texas Southwestern Medical School of Dallas, Dallas, TX; Lawrence S. Friedman, MD, Professor of Medicine, Gastroinstestinal Unit, Massachusetts General Hospital, Boston, MA; and Marvin H. Sleisenger, MD, Distinguished Physician, Department of Veterans Affairs Medical Center, San Francisco, CA, ISBN 0721689736 · Hardback · 2688 Pages · 850 Illustrations, Saunders · Published July 2002 Mandell's Principles and Practices of Infection Diseases 6th Edition (2004) by Gerald L. Mandell MD, MACP, John E. Bennett MD, Raphael Dolin MD, ISBN 0443066434 · Hardback · 4016 Pages Churchill Livingstone Harrison's Principles of Internal Medicine 16th Edtion, The McGraw-Hill Companies, ISBN 0-07-140235-7The Oxford Textbook of Medicine Edited by David A. Warrell, Timothy M. Cox and John D. Firth with Edward J. Benz, Fourth Edition (2003), Oxford University Press, ISBN 0192629220
Usually this is caused by an infection, but this is not always the case. It usually is of acute onset, normally lasting less than 10 days and self-limiting. Sometimes it is referred to simply as 'gastro'. It is often called the stomach flu or gastric flu even though it is not related to influenza.
If the inflammation is limited to the stomach, the term gastritis is used, and if the small bowel alone is affected it is enteritis.
Ætiology
There are several causes of gastroenteritis, most of which infective (virus, bacterium, parasite). Young children and elderly people are most at risk for this condition to be severe or to develop complications.
Travellers' diarrhea
Travellers' diarrhea is seen in people travelling from developed to less developed countries. The pathogens commonly responsible are C. jejuni which is seen in a significant proportion of cases, particularly during cooler seasons, various forms of E. coli, particularly ETEC. But also viruses, Shigella, Salmonella, Giardia, Cryptosporidium, and Cyclospora spp. are seen, though these are less common. Generally the disease is selflimiting, lasting 1 to 5 days.
Viral causes
The most common viral causes of acute gastroenteritis (AGE) in children <5 years of age in both developed countries as well as developing countries are:- rotavirus group A (up to 50% of the cases),
- noroviruses (the most common cause of outbreaks of AGE in all age groups),
- adenoviruses type 40 and 41,
- astrovirus, and
- sapovirus.
Viruses commonly seen in gastroenteritis are: rotaviruses; enteric adenoviruses; small, round structured viruses (SRSVs) and classic human caliciviruses; and astroviruses. Not regularly seen in infectious diarrhoea, but present in the gastrointestinal tract, are enteroviruses, reoviruses, non-group F adenoviruses, toroviruses, coronaviruses, and parvo-viruses. In case of immunocompromised patients (i.e. human immunodeficiency virus (HIV) infected, using corticosteroids or recently treated with chemotherapy) one can find herpes simplex virus (HSV), cytomegalovirus (CMV), and picobirnaviruses.
Bacterial causes
This is less common in developed countries. Campylobacter jejuni is responsible for 5-10% of cases, whereas Salmonella species, Shigella species, and various pathogenic types of Escherichia coli account for a small percentage.In the developing world enterotoxigenic, enteropathogenic and enteroinvasive E. coli are important due to the sheer number of cases, whereas Shigella causes debilitating illness and has increasing resistance against cheap and readily available antibiotics. Cholera, caused by Vibrio cholerae is another important cause of acute diarrhoeal illness and subsequent death in the developing world.
Usually bacterial food poisoning is caused by Bacillus cereus, Salmonella spp., C. botulinum, Shigella spp., toxigenic E. coli (ETEC and EHEC), Clostridium perfringens, Staphylococcus aureus, Vibrio spp. (including V. cholerae and V. parahaemolyticus), and certain species of Campylobacter, Yersinia, Listeria, and Aeromonas.
Parasites
Most frequently dysenteric illness is associated with Entamoeba histolytica, but Balantidium coli, Schistosoma mansoni, S. japonicum, Trichuris trichiura, hookworms, and Trichinella spiralis too can be the causative agent.Outbreaks of Giardia lamblia can cause dehydrating diarrhoea in infants, and Cryptosporidium is known to cause 1-4% of cases of acute diarrhoea in hospitalised infants.
Medication
An important cause to remember is antibiotics associated colitis or pseudomembranous colitis. Therapy with antibiotics (i.e. cephalosporins and clindamycin) or chemotherapeutics (i.e. methotrexate) can result in this condition. Clostridium difficile is inhibited by the normal intestinal flora, antibiotics disturb that balance and C. difficile can multiply. Cytotoxin A, produced by C. difficile, damages the colonic mucosa.Some forms of chemotherapy (i.e. Methotrexate, Irinotecan), through damage to the mucosa (mucositis), can cause stomatitis, oesophagitis, gastritis and enteritis.Holland-Frei Cancer Medicine By Donald W. Kufe, MD, Harvard Medical School, Boston, MA, USA; Raphael E. Pollock, MD, MD Anderson Hospital, University of Texas, Houston, TX, USA; Ralph R. Weichselbaum, MD, Professor and Chairman, Department of Radiation Oncology, Pritzker School of Medicine, Michael Reese/University of Chicago Center for Radiation Therapy, Chicago, IL, USA; Robert C. Bast, Jr., M.D. Anderson Cancer Center, Houston, TX, USA; Ted S. Gansler, MD, MBA; James F. Holland, MD, ScD(hc), Mount Sinai Medical Center, New York, NY, USA; and Emil Frei, III, Harvard Medical School, Boston, MA, USA, 6th edition, 2-Volume Set with CD-ROM, ISBN 1550092138 · Hardback · 2900 Pages · 500 Illustrations BC Decker · Published July 2003
Epidemiology
Globally, diarrhea caused 4.6 million deaths in children in 1980 alone, most of these in the developing world. The Harrison's Principles of Internal Medicine estimates the current total figure to be 2.4 to 2.9 million per year. This number has now come down significantly to approximately 1.5 million deaths annually, largely due to global introduction of proper oral rehydration therapyVictora et al 2000
The incidence in the developed countries is as high as 1-2.5 cases per child per year and a major cause of hospitalisation in this age group.
Age, living conditions, hygiene and cultural habits are important factors. Another factor is the location. Aetiological agents vary depending on the climate. Furthermore, most cases of gastroenteritis are seen during the winter in temperate climates and during summer in the tropics.
Clinical features
The main symptoms include poor feeding in infants, vomiting and fever, usually rapidly followed by diarrhea. Viral diarrhea usually causes frequent watery stools, whereas blood stained diarrhoea may be indicative of bacterial colitis.
The child with gastroenteritis may be lethargic and have signs of dehydration, dry mucous membranes, tachycardia, reduced skin turgor, sunken fontanelles and sunken eye balls, poor perfusion and ultimately shock.
Differential diagnosis
It is important to consider infectious gastroenteritis as a diagnosis per exclusionem. A few loose stools and vomiting may be the result of systemic infection such as pneumonia, septicaemia, urinary tract infection and even meningitis. Surgical conditions like appendicitis, intussusception and, rarely, even Hirschsprung's disease may mislead the clinician.
Non-infectious causes to consider are poisoning with heavy metals (i.e. arsenic, cadmium), seafood (i.e. ciguatera, scombroid, toxic encephalopathic shellfish poisoning) or mushrooms (i.e. Amanita phalloides). Secretory tumours (i.e. carcinoid, medullary tumour of the thyroid, vasoactive intestinal peptide-secreting adenomas) and endocrine disorders (i.e. thyrotoxicosis and Addison's disease) are disorders that can cause diarrhoea. Also pancreatic insufficiency, short-gut syndrome, Whipple's disease, coeliac disease and laxative abuse should be excluded as possibility.
Treatment
Rehydration
The principal treatment of diarrhoeal illness in both children and adults is rehydration, i.e. replenishment of water lost in the stools. Depending on the degree of dehydration, this can be done orally with (oral rehydration solutions (ORS)), commercial or home-made rehydration fluids, or through intravenous delivery. Symptoms may exhibit themselves for up to 6 days. Bowel movements will return to normal within a week after that.Because of the stomach's fragility due to the disease, rehydration through the drinking of fluids must be slow and spaced out as to not overwhelm the stomach and cause further nausea and vomiting. Doctors recommend that one take slow sips every few minutes, and if vomiting still occurs, it's best to refrain from any drinking or eating for the next half hour.
Drug therapy
Antibiotics
When the symptoms are severe one usually starts empirical antimicrobial therapy, i.e. fluoroquinolone. Pseudomembranous colitis is treated by discontinuing the causative agent and starting with metronidazole.Antidiarrhoeal agents
Loperamide is an opioid analogue commonly used for symptomatic treatment of diarrhoea. It slows down gut motility, but does not cross the mature blood-brain barrier to cause the central nervous effect of other opioids. In too high doses, loperamide may cause constipation and significant slowing down of passage of feces, but an appropriate single dose will not slow down the duration of the disease. (Wingate et al, 2001) Although antimotility agents have the risk of exacerbating the condition, this fear is not supported by clinical experience according to Sleisenger & Fordtran's Gastrointestinal and Liver Disease and the Oxford Textbook of Medicine. Nevertheless, Harrison's Principles of Internal Medicine discourages the use of antiperistaltic agents and opiates in febrile dysentery, since they may mask, or exacerbate the symptoms. All these textbooks agree that in severe colitis antimotility drugs should not be used.Loperamide prevents the body from flushing toxins from the gut, and should not be used when an active fever is present or there is a suspicion that the diarrhea is associated with organisms that can penetrate the intestinal walls, such as H7 or salmonella.
Loperamide is also not recommended in children, especially in children younger than 2 years of age, as it may cause systemic toxicity due to an immature blood brain barrier, and oral rehydration therapy remains the main stay treatment for children.
Bismuth subsalicylate (BSS), an insoluble complex of trivalent bismuth and salicylate, is another drug that can be used in mild-moderate cases.
Combining an antimicrobial drug and an antimotility drug, seems to be effective more rapidly.
Antibiotics are of little or no use, unless persistent symptomatic colonisation (as seen in Giardia lamblia infestations) or septicaemia is present.
Complications
Dehydration is the most concerning complication of the diarrhea caused by gastroenteritis and needs prompt rectification by a clinician if severe.
Febrile convulsions are not uncommon in children, especially with rotavirus infections.
Sugar malabsorption is the most common complication, especially in infants. This may result in reappearance of diarrhea once milk, and hence the sugar lactose, is reintroduced into the diet.
Notes
References
- Victora, C. G., Bryce, J., Fontaine, O., & Monasch, R. 2000, 'Reducing deaths from diarrhoea through oral rehydration therapy', Bulletin of The World Health Organization, vol. 78, no. 10, pp. 1246-1255.
- Wingate D. et al. 2001. 'Guidelines for adults on self-medication for the treatment of acute diarrhoea', Alimentary Pharmacology & Therapeutics, vol. 15, no. 6, pp. 773-782.
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Gastroenteritis | Gastroenteritis | Gastro-entérite | Buikgriep
"Gastroenteritis"