Sandbox:GE

# Overview
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.  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 cause by viruses, bacteria or parasites. Most cases of acute gastroenteritis are caused by viruses and among them, Norovirus is the most common etiology for adults. 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 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.

# Classification
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
 EHEC, EIEC, EPEC and EAEC may cause bloody diarrhea, but they are classically associated with watery diarrhea.
 Either Salmonella and Yersinia can cause dysentery.
 Entamoeba histolytica may cause dysentery

# Patient Evaluation

## Initial Evaluation:
Shown below is an algorithm depicting the initial management of acute diarrhea is based on the 2001 IDSA practice guidelines for the management of infectious diarrhea.

## Management:
Illness severity:
- Severe: Total disability due to diarrhea;
- Moderate: Able to function but with forced change in activities due to illness;
- Mild: No change in activities

# Synopsis
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.

# General principles for treatment
- Rehydration with a balanced sodium-glucose solution is The first step for treatment. Oral rehydration solution (ORS) has reduced infant mortality in developing countries by at least 50%. ORS has no effect on disease course however, it's valuable to treat dehydration.
- For infants and the elderly with severe travelers diarrhea (TD) and in anyone who develops profuse cholera-like watery diarrhea, balanced ORS and medical evaluation are advised.
- For most otherwise healthy adults with TD, formal ORS is not needed as they can keep up with fluid losses by taking in salty soups, fruit juices and carbohydrates to provide enough compensation. 
- In severe diarrhea, a balanced ORS can usually be found at a local pharmacy with sodium of 6075 mEq/l and glucose of 7590 mmol/l for replacing salt and water. 
- Bismuth subsalicylates (BSSs) can be administered to control rates of passage of stool and may help travelers function better during bouts of mild to moderate illness. The recommended dose of BSS for therapy of acute diarrhea is 30 ml (525 mg) of liquid formulation or two tablets (263 mg per tablet) chewed well each 3060 min not to exceed eight doses in 24 h. The drug will cause black stools and black tongues.
- In patients receiving antibiotics for TD, adjunctive loperamide therapy can be administered to decrease duration of diarrhea and increase chance for a cure. The recommended dose of loperamide for therapy for adults with diarrhea is 4 mg initially followed by 2 mg after subsequently passed watery stools not to exceed 8 mg per day. Loperamide is not given for more than 48 h. The most valuable use of loperamide in the self-treatment of TD is as a combination drug with antibacterial drugs where the antimotility drug quickly reduces the number of diarrhea stools passed while the antibiotic cures the enteric infection. 
- empiric anti-microbial therapy for routine acute diarrheal infection, except in cases of TD where the likelihood of bacterial pathogens is high enough to justify the potential side effects of antibiotics.
- Use of antibiotics for community-acquired diarrhea should be discouraged as epidemiological studies suggest that most community-acquired diarrhea is viral in origin (norovirus, rotavirus, and adenovirus) and is not shortened by the use of antibiotics.
- Antibiotics shorten the overall duration of moderate-to-severe TD to a little over 24 h and are recommended in TD.  The following table summarizes the recommended antibiotics for TD.

# Prevention

## Non travel setting
- Contaminated foods are major causes of foodborne illness in the United states.
- 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.
- Frequent and effective hand washing and alcohol-based hand sanitizers.
- Rotavirus vaccination is recommended for all infants unless there is a contraindication for it.

## 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.
- Frequent and effective hand washing and alcohol-based hand sanitizers especially for cruise travelers.
- Chemoprophylaxis with Bismuth subsalicylate (BSS) has been shown to reduce the frequency of TD when used during period of risk for 3 weeks. 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.
- Offer the typhoid vaccine to travelers going to countries with high prevalence of typhoid fever.