page_title: Rotaviral gastroenteritis
section_title: Pathophysiology
hierarchical_section_title: Rotaviral gastroenteritis / Pathophysiology
caption_attribution_description: Transmission electron micrograph of an enterocyte 3 days after infection by rotavirus (top). The microvilli have been destroyed. An unifected enterocyte is shown for comparison at the bottom. The bar = approx 500 nm
context_page_description: Rotavirus gastroenteritis is the most common cause of severe diarrhoea among infants and young children. It is caused by Rotavirus, a genus of double-stranded RNA virus in the family Reoviridae. By the age of five, nearly every child in the world has been infected with rotavirus at least once. However, with each infection, immunity develops, and subsequent infections are less severe; adults are rarely affected. There are five species of this virus, referred to as A, B, C, D, and E. Rotavirus A, the most common, causes more than 90% of infections in humans.
  The virus is transmitted by the faecal-oral route. It infects and damages the cells that line the small intestine and causes gastroenteritis. Although rotavirus was discovered in 1973 and accounts for up to 50% of hospitalisations for severe diarrhoea in infants and children, its importance is still not widely known within the public health community, particularly in developing countries. In addition to its impact on human health, rotavirus also infects animals, and is a pathogen of livestock.
context_section_description: The diarrhoea is caused by multiple activities of the virus. Malabsorption occurs because of the destruction of gut cells called enterocytes. The toxic rotavirus protein NSP4 induces age- and calcium ion-dependent chloride secretion, disrupts SGLT1 transporter-mediated reabsorption of water, apparently reduces activity of brush-border membrane disaccharidases, and possibly activates the calcium ion-dependent secretory reflexes of the enteric nervous system. Healthy enterocytes secrete lactase into the small intestine; milk intolerance due to lactase deficiency is a symptom of rotavirus infection, which can persist for weeks. A recurrence of mild diarrhoea often follows the reintroduction of milk into the child's diet, due to bacterial fermentation of the disaccharide lactose in the gut.
caption: Electron micrograph of a rotavirus infected enterocyte (top) compared to an uninfected cell (bottom). The bar = approx. 500 nm
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