Gastroenteritis
Diarrheal disease is responsible for significant morbidity and mortality worldwide, with nearly 1.7 billion cases [1] and at least two million deaths per year, many resulting from consumption of contaminated food [2]. Acute infectious gastroenteritis is d
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Introduction to Gastroenteritis Diarrheal disease is responsible for significant morbidity and mortality worldwide, with nearly 1.7 billion cases [1] and at least two million deaths per year, many resulting from consumption of contaminated food [2]. Acute infectious gastroenteritis is defined as disorder of the physiological functions of stomach, small, and large intestine (see chapter “Overview” under part “Gastrointestinal tract”) due to inflammation of the digestive tract, resulting from bacterial, viral, or parasitic infections (Fig. 1). Noninfectious gastroenteritis may also occur after ingestion of certain types of food and medicines but is less common. Common symptoms include diarrhea, vomiting, abdominal pain, headache, nausea, fatigue, and occasionally fever and chills [3]. Infectious gastroenteritis can occur year-round, but bacterial cases are seen more commonly in warm or summer months because bacterial pathogens can replicate in vitro after contamination of food or water. These diseases are more common in developing nations where sanitation conditions are poor and visitors to these nations commonly develop traveler’s diarrhea. Viral pathogens are not able to replicate in vitro, but tend to survive longer in cold conditions, which facilitates their C. Quigley • X. Jiang (*) Division of Infectious Diseases, Cincinnati Children’s Hospital Medical Center, MLC 7017, 3333 Burnet Ave., Cincinnati, OH 45229, USA e-mail: [email protected]; [email protected]
spread via person-to-person contact. Therefore, viral diseases are more common in the fall/winter seasons when people are indoors more often [4].
Pathophysiology of Gastroenteritis Bacteria Normal bacterial flora populates the gut, increasing in numbers from the stomach to the distal colon (see chapter “Overview” under part “Gastrointestinal tract”) [5]. These bacteria are helpful to the human host by fermenting unused energy substrates; training the immune system; preventing growth of harmful, pathogenic bacteria; regulating the development of the gut; producing vitamins, like vitamin K2; and metabolizing estrogen and androgen hormones [6]. Bacterial gastroenteritis can result from invasion of the gut mucosal surface, attachment to mucosal surfaces and release of toxins, or by toxin production in food prior to ingestion. Invasive bacterial strains, such as Shigella and Campylobacter sp., usually lead to mucosal ulceration (see chapter “Peptic ulcer disease”), abscess formation, and inflammation, which can occur due to invasion of the gut alone, but are exacerbated by toxin production [7]. This process results in severe diarrhea due to secretion of water and electrolytes, sometimes containing mucus and/or blood in the feces with fever, abdominal pain, and rectal tenesmus (a feeling of incomplete defecation), known as dysentery [4].
E. Lammert, M. Zeeb (eds.), Metabolism of Human Diseases, DOI 10.1007/978-3-7091-0715-7_22, © Springer-Verlag Wien 2014
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I. Infectious gastroenteritis Bacterial Viral Parasitic
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