{
  "id": "gastroenteritis",
  "title": "Gastroenteritis",
  "lang": "en",
  "source_lang": "en",
  "summary": "Gastroenteritis is inflammation of the gastrointestinal tract, usually caused by infection, that produces diarrhea, vomiting, and abdominal discomfort.",
  "category": "health",
  "subcategory": "diseases",
  "type": "concept",
  "aliases": [
    "Gastro-enteritis",
    "Stomach flu (informal, usually referring to viral gastroenteritis)",
    "Stomach bug (informal)"
  ],
  "generated_at": "2026-10-12",
  "model": "pro/gpt-6.1-sol",
  "url": "https://aiwiki.page/en/gastroenteritis/",
  "translations": {
    "zh-Hans": {
      "url": "https://aiwiki.page/zh/gastroenteritis/",
      "json": "https://aiwiki.page/zh/gastroenteritis.json"
    }
  },
  "sections": [
    {
      "heading": "",
      "text": "Gastroenteritis is inflammation of the lining of the gastrointestinal tract, principally affecting the intestines and typically producing diarrhea, vomiting, nausea, and abdominal pain. Most cases result from infection with viruses, bacteria, or parasites, although ingested toxins, chemicals, and some medicines can cause similar illness. Gastroenteritis describes a clinical syndrome rather than a single disease with one cause. The informal name “stomach flu” is misleading: viral gastroenteritis is not caused by influenza viruses. (merckmanuals.com)\n\nIts importance ranges from brief, self-limiting illness to severe dehydration and systemic complications. Infants, young children, older adults, and people with impaired immunity are particularly vulnerable to fluid and electrolyte losses. Infectious gastroenteritis also contributes to the substantial global burden of diarrhoeal disease and causes outbreaks associated with contaminated food, unsafe water, and close-contact settings. Understanding its causes, transmission, physiological effects, diagnosis, and clinical management connects individual illness with public health, sanitation, food safety, and vaccination. (niddk.nih.gov)"
    },
    {
      "heading": "Definition, terminology, and clinical boundaries",
      "text": "Gastroenteritis is a gastrointestinal inflammatory syndrome conventionally defined as inflammation of the lining of the stomach and the small and large intestines. In clinical usage, however, the term does not require demonstrated inflammation in all three locations: intestinal involvement predominates in many infections, and viral gastroenteritis is specifically described as an intestinal infection. The syndrome commonly includes diarrhea, vomiting, nausea, and abdominal cramps, sometimes accompanied by fever. Most cases are infectious, but gastrointestinal injury or irritation from certain chemicals or medications can produce noninfectious gastroenteritis. Thus, the name describes a clinical syndrome rather than a single pathogen or a uniform anatomical lesion. (merckmanuals.com)\n\nDiarrhea is a symptom, not a synonym for gastroenteritis. It is commonly defined as passage of loose, watery stools three or more times daily, or more frequently than is normal for the individual. Gastroenteritis is one cause of that symptom; diarrhea also occurs with food intolerances, medication effects, and other digestive disorders. Conversely, vomiting may dominate a gastroenteritis episode, so the clinical label is not simply another name for frequent bowel movements. Distinguishing the symptom from the syndrome prevents every episode of loose stool from being classified as gastrointestinal inflammation or infection. (niddk.nih.gov)\n\nMore anatomically specific terms identify the affected region. Gastritis denotes inflammation of the stomach lining; isolated gastritis is therefore distinct from an illness involving the intestines. It is also distinguished from gastropathy, in which the gastric lining is damaged with little or no inflammation. Enteritis refers to intestinal inflammation, particularly of the small intestine, whereas colitis denotes inflammation of the colon. These labels can overlap with the broader gastroenteritis syndrome, but they are not interchangeable: colitis identifies a site of inflammation without specifying whether its cause is infectious, and radiation enteritis provides an example of intestinal inflammation caused by a noninfectious exposure. (niddk.nih.gov)\n\n“Stomach flu” is an informal, medically inaccurate name, usually applied to viral gastroenteritis. It is misleading in two respects: the principal infection is intestinal rather than gastric, and the causative viruses are not influenza viruses. Influenza vaccination consequently does not protect against viral gastroenteritis. The colloquial expression does not establish either an anatomical diagnosis or the identity of the infectious agent. (niddk.nih.gov)\n\nFoodborne illness and gastroenteritis are overlapping rather than identical categories. Foodborne illness classifies disease by acquisition through contaminated food or drink; gastroenteritis classifies it by the gastrointestinal syndrome. Gastroenteritis acquired through person-to-person transmission is not necessarily foodborne, while foodborne disease can produce effects outside the gastrointestinal tract. Foodborne botulism, for example, is principally a neurotoxin-mediated illness that can cause paralysis. Moreover, foodborne gastroenteritis can result either from infection or from ingestion of toxins already present in food, so “food poisoning” does not by itself establish that a microorganism is multiplying within the patient. (niddk.nih.gov)"
    },
    {
      "heading": "Epidemiology and global disease burden",
      "text": "The World Health Organization (WHO), in its fact sheet dated March 7, 2024, estimated nearly 1.7 billion episodes of childhood diarrhoeal disease annually, with approximately 443,832 deaths among children younger than five years and a further 50,851 deaths among children aged five to nine. These are estimates for the broader category of diarrhoeal disease, not gastroenteritis-specific counts or totals for a particular pathogen. Episodes also do not represent unique affected children, because an individual may experience repeated illness. WHO identified diarrhoeal disease as the third leading cause of death among children aged 1–59 months. Children with malnutrition or impaired immunity have a particularly high risk of life-threatening disease. (who.int)\n\nGeographical differences involve both exposure frequency and the likelihood that an episode becomes fatal. Inadequate drinking-water, sanitation, and hygiene permit repeated contamination of food, water, and household environments. WHO reports that children younger than three in low-income countries experience, on average, three diarrhoeal episodes annually. These environmental exposures interact with nutritional status and access to effective healthcare rather than determining severity independently. (who.int) The Global Burden of Disease Study estimated 59.0 million disability-adjusted life-years attributable to diarrhoeal diseases in 2021, including 30.9 million among children younger than five. Its regional estimates placed the largest burdens in sub-Saharan Africa and South Asia; these figures, like WHO’s totals, concern diarrhoeal diseases rather than a separately enumerated gastroenteritis syndrome. (pmc.ncbi.nlm.nih.gov)\n\nIn the United States, norovirus is a leading contributor to acute gastroenteritis across all age groups and the leading cause of foodborne illness. A 2013 synthesis of population-based studies estimated 19–21 million norovirus illnesses annually; this total includes infections acquired through all transmission routes, not foodborne infections alone. The distinction matters because most reported norovirus outbreaks involve direct spread between people. Young children have the highest rates of norovirus-associated medical visits, while adults aged 65 and older bear the greatest mortality risk. Thus, high overall frequency does not imply an even distribution of severe outcomes across age groups. (wwwnc.cdc.gov)\n\nRotavirus has been especially important in severe childhood gastroenteritis. Before routine rotavirus vaccination began in the United States in 2006, an estimated 95% of children had experienced infection by their fifth birthday, and rotavirus accounted for 30–50% of gastroenteritis hospitalizations among children younger than five. Clinical illness was most frequent at 3–35 months of age. (cdc.gov) Vaccination subsequently changed both disease frequency and seasonal patterns: national laboratory surveillance found that median annual test positivity declined from 25.6% in 2000–2006 to 6.1% in 2007–2018, while median season duration shortened from 26 to nine weeks. These are surveillance indicators, not population incidence rates. (cdc.gov) Seasonality also varies by pathogen and latitude. U.S. norovirus outbreaks are most common from November through April; rotavirus traditionally peaks in winter and spring in temperate settings, but shows less pronounced seasonality in tropical climates. (cdc.gov)\n\nRecorded cases substantially underrepresent community illness. Mild, self-limited episodes often do not lead to medical consultation; among patients who seek care, limited stool testing can leave the cause unspecified. Norovirus burden studies consequently combine community surveys, laboratory-confirmed surveillance, and statistical attribution rather than relying solely on diagnostic codes. (wwwnc.cdc.gov) Outbreak reports introduce another ascertainment filter: clusters must first be recognized, investigated, and reported. CDC surveillance analyses have documented variation in reporting that probably reflects differences in underreporting rather than true differences in outbreak incidence. Consequently, counts from public-health surveillance describe detected illness and cannot be read directly as the total number of gastroenteritis episodes in a population. (cdc.gov)"
    },
    {
      "heading": "Viral causes",
      "text": "Noroviruses, rotaviruses, enteric adenoviruses, astroviruses, and sapoviruses are established causes of viral gastroenteritis. Their characteristic age distributions and time courses overlap: norovirus affects all ages, whereas rotavirus, enteric adenovirus, and astrovirus disease is concentrated in infants and young children. Watery diarrhea, vomiting, abdominal cramps, and sometimes fever occur with several of these infections, so neither symptoms nor illness duration definitively identifies the causative virus. These clinical patterns describe typical cases rather than diagnostic criteria. (niddk.nih.gov)\n\nNorovirus typically produces abrupt vomiting and non-bloody diarrhea after an incubation period of 12–48 hours. Nausea, abdominal cramps, and low-grade fever may accompany the illness, which usually resolves within 1–3 days. Its importance extends beyond childhood disease: adults and older people also develop symptomatic infection. Repeated episodes are possible because infection with one norovirus type does not necessarily confer protection against other types, and the duration of type-specific protection is uncertain. Thus, previous illness does not establish durable immunity to the genetically diverse noroviruses encountered subsequently. (cdc.gov)\n\nRotavirus is particularly associated with severe childhood gastroenteritis. Before vaccination, the highest incidence of clinical illness in the United States occurred at 3–35 months of age, and rotavirus accounted for 30–50% of gastroenteritis hospitalizations among children younger than five. Infection ranges from asymptomatic carriage to profuse watery diarrhea with vomiting, fever, and substantial dehydration; the first infection after three months of age is generally the most severe. Symptoms begin approximately two days after exposure and commonly persist for 3–8 days. Adults can be infected, but their infections are often asymptomatic. (cdc.gov)\n\nRoutine rotavirus vaccination has changed this disease pattern. RotaTeq was introduced in the United States in 2006 and Rotarix in 2008. CDC estimates first-year protection of 85–98% against severe rotavirus illness and hospitalization, compared with 74–87% against illness of any severity. Following vaccine introduction, rotavirus-associated hospital and emergency-department use declined markedly, and surveillance documented a shift from annual seasonal peaks to a biennial pattern of activity. These changes concern rotavirus specifically: protection against severe rotavirus disease does not imply protection against gastroenteritis caused by norovirus or other enteric viruses. (cdc.gov)\n\nEnteric adenoviruses principally comprise human adenovirus species F, types 40 and 41; these are distinct from the adenovirus types commonly associated with respiratory disease. They cause predominantly pediatric gastroenteritis, with diarrhea, vomiting, and sometimes fever. Compared with the brief course typical of norovirus, adenovirus illness often lasts longer: symptoms generally begin 3–10 days after exposure and persist for one to two weeks. Astrovirus also predominantly affects infants and young children, although adults may be infected. Its usual incubation period is approximately 4–5 days, followed by 1–4 days of gastrointestinal symptoms. These differences in timing can inform an etiological assessment but cannot independently establish the pathogen. (wwwnc.cdc.gov)\n\nSapovirus is another calicivirus associated with childhood diarrhea and with outbreaks involving adults, including residents of long-term-care facilities. Its pediatric importance was demonstrated in a Peruvian birth-cohort study published in 2018: among 100 children followed to age two, 82% had at least one detected sapovirus infection and 64% had at least one sapovirus-associated diarrheal episode. Symptomatic illness commonly involves diarrhea and vomiting and generally resolves within a week, although longer episodes occur. Viral detection can outlast clinical illness: the same cohort documented a median stool-shedding period of 18.5 days, without a significant difference between symptomatic and asymptomatic infections. (wwwnc.cdc.gov)"
    },
    {
      "heading": "Bacterial causes",
      "text": "Campylobacter, nontyphoidal Salmonella, Shigella, pathogenic Escherichia coli, Vibrio, and Yersinia cause enteric illness through different combinations of toxin production, mucosal injury, and invasion. Enterotoxigenic infections predominantly produce watery diarrhea by altering intestinal secretion, whereas invasive infections commonly produce inflammation, fever, and sometimes bloody stools. Shiga-toxin-producing infections form a distinct category: toxin-mediated injury can cause hemorrhagic colitis without the invasive mechanism characteristic of shigellosis. These categories overlap clinically, so watery or bloody diarrhea alone does not identify the organism. (idsociety.org)\n\nCampylobacter jejuni accounts for almost 90% of human campylobacteriosis; C. coli and several other species account for smaller proportions. Infection is strongly associated with raw or undercooked poultry, although unpasteurized milk, untreated water, and animal contact are also recognized sources. The incubation period is typically 2–5 days, followed by abdominal pain, fever, and diarrhea that is often bloody. Nontyphoidal Salmonella likewise causes acute gastroenteritis, with diarrhea, abdominal cramps, and fever; infection can sometimes extend beyond the intestine into the bloodstream. This differs from infection with Salmonella Typhi or Paratyphi, which causes the predominantly systemic illnesses typhoid and paratyphoid fever rather than ordinary nontyphoidal salmonellosis. (cdc.gov)\n\nShigella invades colonic epithelial cells, producing inflammatory diarrhea that may develop into dysentery, with blood in the stool and a persistent urge to defecate despite an empty bowel, termed tenesmus. The four recognized species are S. sonnei, S. flexneri, S. boydii, and S. dysenteriae. An infectious dose as low as 10–100 organisms helps explain efficient person-to-person transmission. Yersinia enterocolitica and Y. pseudotuberculosis also cause enteric disease. Raw or undercooked pork is a characteristic exposure, particularly for Y. enterocolitica. Young children may have fever and bloody diarrhea, whereas older children and adults may develop prominent right-sided abdominal pain resembling appendicitis. (wwwnc.cdc.gov)\n\nPathogenic *E. coli* is classified into pathotypes rather than treated as a single diarrheal agent. Enterotoxigenic E. coli (ETEC), an important cause of travelers’ diarrhea, produces heat-labile and/or heat-stable enterotoxins that promote intestinal fluid and electrolyte loss. Enteroinvasive E. coli (EIEC) produces an invasive, sometimes bloody illness resembling shigellosis. Enteropathogenic (EPEC), enteroaggregative (EAEC), and diffusely adherent (DAEC) strains usually cause watery diarrhea; EPEC and EAEC can be associated with prolonged illness. Shiga toxin–producing E. coli (STEC), including O157:H7 and non-O157 strains, can cause severe abdominal cramps and bloody diarrhea, often with little or no fever. Some infections lead to hemolytic uremic syndrome, linking an intestinal infection to systemic vascular and kidney injury. (cdc.gov)\n\nCholera is a toxin-mediated intestinal infection associated with toxigenic Vibrio cholerae O1 and O139. Cholera toxin drives intestinal secretion, producing acute watery diarrhea; severe disease may feature profuse “rice-water” stools, although infections can also be mild or asymptomatic. Thus, cholera is a specific cause of acute watery diarrhea, not a synonym for that broader clinical syndrome. Other Vibrio species cause different illnesses: V. parahaemolyticus commonly produces gastroenteritis after consumption of contaminated raw or undercooked seafood, especially shellfish. In an Australian outbreak during September 2021–January 2022, 268 cases were identified, and 97% reported eating Australia-grown oysters. (cdc.gov)\n\n*Clostridioides difficile*–associated diarrhea and colitis have distinct antibiotic-associated and healthcare epidemiology. Antibiotics can disrupt the protective intestinal microbial community, permitting C. difficile to multiply; toxin-producing strains cause diarrhea and colonic inflammation, including pseudomembranous colitis. Toxins A and B are central to disease production. Infection is particularly associated with hospitals and nursing homes, but also occurs in the community and in people without recent antibiotic exposure. Its environmentally persistent spores contribute to transmission. Nevertheless, antibiotic-associated diarrhea is not invariably caused by C. difficile, and the presence of the organism alone does not establish toxin-mediated disease. (cdc.gov)"
    },
    {
      "heading": "Parasitic causes",
      "text": "Giardia duodenalis, Cryptosporidium species, Cyclospora cayetanensis, and Entamoeba histolytica are unicellular protozoal parasites associated with intestinal illness. They differ from helminths—multicellular parasitic worms such as roundworms, tapeworms, and flukes—which can also cause gastrointestinal symptoms but have distinct life cycles and patterns of disease. Protozoal infections are particularly important among infectious causes of persistent diarrhea, rather than being restricted to short episodes of acute gastroenteritis. Their presentations range from watery diarrhea and impaired nutrient absorption to invasive disease of the colon with dysentery. (cdc.gov)\n\nGiardia duodenalis, also called G. lamblia or G. intestinalis, causes giardiasis. Infection follows ingestion of cysts, which release trophozoites in the small intestine. These motile forms multiply in the proximal intestinal lumen and attach to the mucosa through a ventral adhesive disk. Illness may include watery diarrhea, bloating, cramps, and conspicuously greasy, foul-smelling stools; recurrent infection-related symptoms and malabsorption distinguish some cases from brief viral illness. Symptoms commonly begin one to two weeks after exposure and last two to six weeks, although asymptomatic infection and longer courses occur. Poor absorption of fat and other nutrients can contribute to weight loss. Untreated drinking water, including water consumed during wilderness activities, is a relevant exposure, but infection also spreads between people. (cdc.gov)\n\nCryptosporidiosis is caused principally by Cryptosporidium hominis and C. parvum. The parasites develop at the brush border of intestinal epithelial cells, predominantly in the small intestine. Their life cycle produces thick-walled oocysts that pass into the environment and thin-walled forms involved in internal autoinfection. Unlike Cyclospora oocysts, excreted Cryptosporidium oocysts are immediately infectious. Watery diarrhea is characteristic, with an incubation period of two to ten days; illness in immunocompetent people typically resolves within two to three weeks. In people with substantial immunodeficiency, infection can become prolonged and cause severe malabsorption and wasting. Exposure may involve drinking or recreational water, infected people, or animals; cattle, particularly calves, are associated with zoonotic C. parvum infection. (cdc.gov)\n\nCyclospora cayetanensis invades epithelial cells of the small intestine and causes watery diarrhea that may remit and recur. Symptoms begin, on average, about one week after infection, and untreated illness can persist for many weeks. A distinguishing biological feature is that freshly excreted oocysts must mature, or sporulate, in the environment over days to weeks before becoming infectious. Consequently, immediate person-to-person transmission is unlikely. Contaminated water and fresh produce are important sources; outbreaks in the United States and Canada have been linked to imported produce. The organism is especially relevant to exposure histories involving tropical or subtropical regions, although locally acquired foodborne cases also occur. (cdc.gov)\n\nEntamoeba histolytica produces a different pattern: trophozoites may remain within the intestinal lumen without symptoms or invade the colonic mucosa, causing amebic colitis and dysentery. This invasive presentation contrasts with the predominantly watery or malabsorptive illness associated with the other organisms. Infection follows ingestion of mature cysts in fecally contaminated food, water, or hands. Species identification matters because the generally nonpathogenic E. dispar is morphologically indistinguishable from E. histolytica on routine microscopy; species-specific testing separates these findings. (cdc.gov)\n\nDuration, exposure, and immune status guide etiological investigation. The 2017 Infectious Diseases Society of America guideline identifies intestinal parasites as an important consideration in travelers whose diarrhea lasts at least 14 days. Untreated-water consumption, recreational-water exposure, and fresh-produce exposure help distinguish plausible causes without establishing the diagnosis. Advanced HIV infection and other impairments of cell-mediated immunity increase the relevance of severe, chronic, or relapsing protozoal infection. Routine stool examination for ova and parasites does not necessarily include adequate testing for Cryptosporidium or Cyclospora, so the organisms included in an investigation depend on the laboratory methods requested. (idsociety.org)"
    },
    {
      "heading": "Foodborne intoxication and noninfectious causes",
      "text": "Foodborne intoxication results from ingestion of a toxin already present in food, rather than from an infection requiring viable organisms to establish themselves in the host. The distinction concerns where the harmful substance is produced: in staphylococcal food poisoning and the emetic form of Bacillus cereus illness, bacteria multiply and generate toxins in food before consumption. Consequently, killing the organisms during subsequent cooking does not necessarily eliminate the hazard. These illnesses can produce the vomiting, abdominal cramps, and diarrhea associated with gastroenteritis without requiring microbial invasion of the intestinal lining. (cdc.gov)\n\n*Staphylococcus aureus* food poisoning illustrates the rapid onset characteristic of preformed-toxin exposure. Organisms carried on the skin or in the nose can contaminate handled foods, including sliced meats, sandwiches, puddings, and pastries; unsuitable storage temperatures then permit bacterial multiplication and enterotoxin production. Symptoms usually begin suddenly 30 minutes to eight hours after ingestion and include nausea, vomiting, cramps, and diarrhea, generally lasting 24 hours or less. Ordinary cooking can kill the bacteria while leaving their heat-resistant enterotoxins active. A concrete example occurred in Florida in 1997: an outbreak associated with precooked ham demonstrated that a previously cooked food could remain a vehicle for staphylococcal intoxication after contamination and inadequate temperature control. The CDC investigation emphasized that toxin-containing food may look and taste normal. (cdc.gov)\n\n*Bacillus cereus* causes two mechanistically distinct foodborne syndromes, only one of which is a straightforward preformed-toxin intoxication. In the emetic syndrome, the bacterium produces cereulide in food, frequently cooked starchy dishes such as rice or pasta. Its resistant spores can survive heating, subsequently germinating and allowing bacterial growth under favorable storage conditions. Cereulide resists heat, acid, and digestive enzymes; nausea and vomiting typically develop within 0.5–6 hours. In the diarrheal syndrome, ingested organisms or spores give rise to enterotoxin-producing cells in the small intestine. This is therefore a toxin-mediated infection, or toxicoinfection, rather than the same mechanism as cereulide intoxication. Its enterotoxins are comparatively sensitive to heat and digestive conditions, and abdominal cramps and diarrhea generally begin 6–24 hours after ingestion. (fda.gov)\n\nChemical-associated gastroenteritis can follow ingestion of contaminated food or water containing arsenic or metals such as lead, mercury, and cadmium. These exposures are toxicological rather than infectious, and their effects depend on the substance’s chemical form, dose, and duration of exposure. Acute ingestion of substantial amounts of inorganic arsenic can directly injure gastrointestinal epithelial cells and interfere with cellular enzyme function. The resulting illness may include severe abdominal pain, vomiting, and hemorrhagic diarrhea; inflammation and necrosis of the gastrointestinal mucosa distinguish this injury from uncomplicated gastrointestinal upset. Chronic low-level arsenic exposure, often through contaminated drinking water, has a different clinical pattern and should not be treated as synonymous with an acute gastroenteritis episode. Natural toxins in poisonous mushrooms and certain seafood can also cause noninfectious gastrointestinal illness. (merckmanuals.com)\n\nMedication-associated gastrointestinal symptoms likewise encompass more than one mechanism. Chemotherapy drugs, immunotherapy, colchicine, digoxin, antibiotics, and laxatives are among exposures associated with nausea, vomiting, or diarrhea. However, drug-induced diarrhea is not automatically gastroenteritis: an adverse effect does not by itself establish inflammation of the stomach or intestines. Magnesium-containing antacids and sugar alcohols such as sorbitol, mannitol, or xylitol in liquid medicines can cause diarrhea without demonstrating inflammatory mucosal injury. Medication history therefore helps distinguish direct gastrointestinal toxicity or irritation from other adverse effects and from coincident infection; symptom onset in relation to starting a medicine and changes after its withdrawal provide evidence relevant to attribution. (merckmanuals.com)"
    },
    {
      "heading": "Transmission and exposure settings",
      "text": "Infectious gastroenteritis commonly spreads by the fecal–oral route: pathogens shed in feces reach another person’s mouth through contaminated hands, food, drinking water, or objects. Transmission does not require visible fecal contamination. After toileting or changing diapers, contaminated fingers can transfer organisms to food, utensils, toys, and bathroom fixtures; touching these objects and then eating or placing fingers in the mouth completes the route. Person-to-person spread therefore includes both direct contact and indirect transfer through the environment. These mechanisms concern infectious causes, rather than medication-related or chemical-associated gastrointestinal illness. (niddk.nih.gov)\n\nNorovirus also spreads through material expelled during vomiting. A vomiting episode can disperse small droplets containing virus onto nearby food and surfaces, which subsequently become sources of ingestion. Airborne dispersal during vomiting should therefore be distinguished from a respiratory infection: contaminated material ultimately reaches the gastrointestinal tract. Norovirus’s low infectious dose and environmental persistence facilitate transmission through shared spaces. Viral shedding can occur before symptoms appear and can continue in stool for two weeks or more after recovery, so disappearance of vomiting and diarrhea does not immediately end the potential for transmission. (beta.cdc.gov)\n\nShared meals create common-source exposure, in which several people acquire infection from the same contaminated food or beverage rather than initially infecting one another. Food may become contaminated during production, preparation, or serving; an infected food handler can contaminate ready-to-eat items that receive no subsequent cooking. Raw oysters provide another example: filter-feeding shellfish can concentrate norovirus from contaminated water. Common-source and person-to-person transmission can occur sequentially. A cruise-ship investigation published in 2005 described an initial outbreak suspected to originate from food or water, followed by continued person-to-person spread; a shared exposure need not account for every later case. (portugues.cdc.gov)\n\nChildcare facilities combine close contact, diaper changing, shared toys, and children’s frequent hand-to-mouth activity. Shigella, for example, can move from contaminated changing tables, diaper pails, or bathroom fixtures to children’s hands. Hospitals and long-term-care institutions likewise bring susceptible people into repeated contact with staff, other patients, and shared environments; norovirus can spread rapidly within these facilities. Cruise ships provide similar opportunities through close living quarters and congregate activities. The setting identifies opportunities for exposure, not a unique transmission route: institutional outbreaks may involve contaminated food, direct contact, and environmental contamination together. (cdc.gov)\n\nRecreational water becomes a vehicle when swimmers swallow water contaminated by feces. Pools, splash pads, lakes, and rivers can transmit organisms including Cryptosporidium, Giardia, Shigella, norovirus, and pathogenic Escherichia coli. Contamination can follow a diarrheal accident or the washing of small amounts of fecal material from swimmers’ bodies. Chlorination does not eliminate every pathogen immediately: Cryptosporidium is especially chlorine-tolerant and can survive for days in properly chlorinated pool water. Consequently, a treated pool and an untreated lake represent different environmental conditions, but both can support common-source enteric exposure. (cdc.gov)\n\nAnimal-associated transmission involves an animal reservoir rather than an infected human as the original source. Campylobacter infection can follow contact with infected animals, consumption of undercooked poultry or unpasteurized milk, or ingestion of contaminated untreated water. Such zoonotic transmission can also occur in commercial pet settings: a United States investigation published in 2018 identified 118 people in 18 states with outbreak-associated Campylobacter jejuni illness during 2016–2018, including 29 pet-store employees, and implicated puppies distributed through pet stores. This distinguishes animal-associated acquisition from human-to-human spread, although both ultimately can involve ingestion of fecally contaminated material. (cdc.gov)"
    },
    {
      "heading": "Pathophysiology",
      "text": "Gastroenteritis disrupts the balance between intestinal absorption, secretion, and epithelial barrier function. Normally, approximately 8–9 liters of fluid, comprising ingested liquids and digestive secretions, pass through the intestine each day, while only about 100–200 milliliters leave in stool. Enterocytes—the epithelial cells lining the intestine—absorb nutrients and electrolytes, with water following osmotic gradients. Pathogens can reduce absorptive surface area, interfere with membrane transporters, increase secretion, or disrupt the tight junctions between adjacent cells. These changes produce diarrhea when fluid delivery exceeds the intestine’s capacity for reabsorption; substantial losses can occur without extensive tissue destruction. (pmc.ncbi.nlm.nih.gov)\n\nOsmotic diarrhea develops when poorly absorbed solutes remain in the intestinal lumen and retain water through osmosis. Viral injury to small-intestinal villus enterocytes can reduce absorptive capacity and the activity of brush-border enzymes, including those responsible for carbohydrate digestion. Undigested or unabsorbed carbohydrates consequently add an osmotic load. Rotavirus illustrates how mechanisms overlap: impaired carbohydrate digestion and absorption contribute an osmotic component, while its nonstructural protein NSP4 alters intracellular calcium signaling and supports secretory and neural responses. Osmotic diarrhea generally diminishes when the responsible solute is no longer entering the bowel, whereas secretory diarrhea can persist independently of food intake. These are physiological distinctions, not mutually exclusive categories of infection. (merckmanuals.com)\n\nSecretory diarrhea results from increased electrolyte secretion, reduced electrolyte absorption, or both, with water moving into or remaining within the lumen. In cholera, cholera toxin modifies the stimulatory G-protein \\(G_s\\), sustaining adenylate cyclase activity and increasing cyclic adenosine monophosphate, or cAMP. This activates protein kinase A and the CFTR chloride channel, increasing chloride secretion; accompanying changes in sodium transport favor net salt and water loss. Enterotoxigenic Escherichia coli provides two related examples: its heat-labile toxin acts through cAMP, whereas its heat-stable toxin activates guanylyl cyclase C and increases cyclic guanosine monophosphate, or cGMP. Thus, bacteria remaining at the mucosal surface can cause pronounced watery diarrhea through toxin-mediated signaling rather than invasion. (pmc.ncbi.nlm.nih.gov)\n\nInflammatory diarrhea involves mucosal injury and the host response to infection. Organisms such as Shigella and Salmonella invade intestinal tissue, while other pathogens damage epithelial cells through cytotoxins. The resulting inflammation recruits leukocytes and releases cytokines and other mediators that alter epithelial transport, increase permeability, and promote secretion. Ulcerated mucosa can release blood, mucus, proteins, and inflammatory cells into the lumen while losing absorptive function. Invasion is therefore neither necessary for all diarrhea nor the sole route to inflammatory disease: toxin-mediated epithelial damage can also provoke marked inflammation. Secretory and osmotic components frequently accompany this inflammatory process. (merckmanuals.com)\n\nVomiting adds a separate route of fluid loss and can limit replacement by oral intake. Experimental work reported in 2011 showed that rotavirus NSP4 stimulated serotonin release from human enterochromaffin cells; infected mice also showed activation of brainstem structures associated with emetic signaling. These findings support a mechanism linking intestinal infection to neural pathways involved in vomiting, rather than requiring primary stomach injury. Together, vomiting and diarrhea remove water and dissolved electrolytes from the body. When losses exceed intake, they disrupt fluid homeostasis; the resulting clinical complications are distinct from the intestinal mechanisms generating those losses. (pmc.ncbi.nlm.nih.gov)"
    },
    {
      "heading": "Symptoms and clinical course",
      "text": "The characteristic symptoms are diarrhea, vomiting, nausea, cramping abdominal pain, and sometimes fever. Reduced appetite may accompany the illness. These manifestations occur in different combinations: vomiting may be prominent, whereas other episodes are dominated by frequent loose stools. Viral gastroenteritis typically produces watery diarrhea; blood or mucus can occur in bacterial enteric infections, including salmonellosis. Stool frequency, consistency, and volume vary, and neither vomiting nor fever is present in every case. Diarrhea is conventionally defined as three or more loose or liquid stools in 24 hours, or stool passage more frequent than normal for the individual; frequent formed stools alone do not meet this definition. (niddk.nih.gov)\n\nClinical descriptions distinguish stool appearance from illness duration. Acute watery diarrhea consists of loose, watery stools without visible blood and commonly lasts several hours to several days; cholera is one cause of this syndrome. Acute bloody diarrhea is termed dysentery, often characterized by frequent, scant stools containing blood and mucus. Persistent diarrhea lasts at least 14 days, whether or not blood is present. Terminology varies slightly between classification systems: the 2017 Infectious Diseases Society of America guideline distinguishes acute diarrhea lasting less than seven days, prolonged diarrhea lasting 7–13 days, persistent diarrhea lasting 14–29 days, and chronic diarrhea lasting 30 days or longer. These are clinical categories rather than pathogen-specific diagnoses. (who.int)\n\nThe incubation period—the interval between exposure and symptom onset—is distinct from the duration of symptomatic illness. Norovirus symptoms usually begin 12–48 hours after exposure and last 1–3 days, illustrating a short-incubation, rapidly resolving course. Rotavirus symptoms generally begin after about two days and last 3–8 days. Enteric adenovirus has a longer typical incubation of 3–10 days, with symptoms lasting one to two weeks. Thus, even among viral causes, neither onset nor recovery follows a universal timetable, and illness continuing beyond a week does not by itself establish a bacterial or parasitic cause. (niddk.nih.gov)\n\nOther causes show different temporal patterns. Staphylococcal food intoxication can produce sudden nausea, vomiting, and diarrhea within 30 minutes to eight hours of eating contaminated food because the illness follows ingestion of preformed enterotoxin. Nontyphoidal Salmonella symptoms usually begin six hours to six days after infection and last 4–7 days. Campylobacter symptoms generally begin after 2–5 days and resolve within approximately seven days; diarrhea may be bloody and accompanied by fever and cramps. Giardiasis can develop after an incubation of 1–14 days, averaging seven days, and its acute illness usually lasts 1–3 weeks; chronic infection may instead produce recurrent symptoms. (cdc.gov)\n\nSymptom patterns narrow possible causes but cannot reliably identify the organism. Bloody diarrhea, fever, and marked abdominal cramps are associated with several bacterial infections rather than one distinctive pathogen. Conversely, Shiga-toxin-producing Escherichia coli infection may produce severe abdominal tenderness and bloody diarrhea with little or no fever, so absence of fever does not establish a viral cause. Watery diarrhea also occurs across viral, bacterial, and parasitic infections. Clinical diagnosis therefore incorporates the timing and course of illness alongside exposure history and, in selected circumstances, laboratory identification; stool appearance or a presumed incubation interval alone is insufficient. (idsociety.org)"
    },
    {
      "heading": "Vulnerable populations and host factors",
      "text": "Infants and young children are particularly susceptible to rapid fluid depletion during gastroenteritis. Compared with older children, infants have a higher body surface-to-volume ratio and metabolic rate, relatively smaller fluid reserves, and complete dependence on caregivers for fluid intake. Vomiting can interrupt feeding while diarrhea continues to remove water and electrolytes, leaving little margin between ongoing losses and inadequate replacement. The US Centers for Disease Control and Prevention’s 2003 pediatric gastroenteritis report identified these physiological and practical factors as reasons for infants’ heightened vulnerability. Prematurity, metabolic disorders, and pre-existing kidney disease can further reduce their capacity to tolerate an acute illness. The National Institute of Diabetes and Digestive and Kidney Diseases notes that severe dehydration can develop in newborns and infants within one or two days of diarrheal illness. (cdc.gov)\n\nOlder adults also have increased susceptibility to severe outcomes, although chronological age alone does not determine severity. Age-related decline in kidney function reduces physiological reserve and increases vulnerability to acute injury; diabetes and hypertension can accelerate this decline. Consequently, an older adult with pre-existing renal impairment has less reserve when gastrointestinal fluid losses disrupt fluid balance. Advanced age and particular comorbid conditions also affect pathogen-specific risk: the Infectious Diseases Society of America’s 2017 guidelines identify advanced age and cirrhosis among the risk factors for invasive nontyphoidal Salmonella infection. (nia.nih.gov) The age gradient is especially evident in norovirus-associated mortality. CDC’s May 2024 estimates attributed approximately 900 US deaths annually to norovirus, mostly among adults aged 65 years or older. This is a pathogen-specific estimate, not a count of deaths from all gastroenteritis. (cdc.gov)\n\nImpaired immune function can change both the range of enteric pathogens causing illness and the ability to clear them. Relevant host factors include primary immunodeficiencies, advanced HIV infection, cytotoxic chemotherapy, and immunosuppressive treatment after organ transplantation. Protozoal infections such as cryptosporidiosis, cystoisosporiasis, and cyclosporiasis are more likely to become severe, chronic, or relapsing when cell-mediated immunity is impaired; chronic, severe norovirus infection has also been documented in transplant recipients. (idsociety.org) Cryptosporidiosis illustrates the importance of the degree of immune impairment: NIH guidelines identify a CD4 T-lymphocyte count below \\(100\\ \\text{cells/mm}^{3}\\) as the level typically associated with the greatest risk of prolonged, severe, or extraintestinal disease. HIV infection therefore does not imply a uniform risk across all patients. (clinicalinfo.hiv.gov) Persistent diarrhea in an immunocompromised person is not necessarily infectious, because chemotherapy and antiretroviral medicines can themselves cause gastrointestinal adverse effects. (idsociety.org)\n\nRecurrent diarrheal illness and malnutrition reinforce one another, particularly during early childhood. Illness reduces food intake through poor appetite and vomiting, decreases intestinal nutrient absorption, and increases nutrient requirements associated with infection. Repeated or prolonged episodes can therefore cause weight loss and interrupt growth, especially when nutritional recovery between episodes is incomplete. Conversely, undernutrition weakens immune defenses and is associated with diarrhea that is more frequent, more severe, and longer-lasting than in well-nourished children. These mechanisms are described in the World Health Organization’s pediatric hospital-care guidance and its accounts of childhood undernutrition. The relationship applies to diarrheal disease broadly, rather than exclusively to confirmed infectious gastroenteritis. (ncbi.nlm.nih.gov)"
    },
    {
      "heading": "Dehydration and other complications",
      "text": "Dehydration develops when losses through diarrhea and vomiting exceed fluid intake. Clinical features include reduced urine output, concentrated urine, dry oral mucous membranes, thirst, sunken eyes, and reduced skin turgor—the delayed return of pinched skin to its usual position. Infants may produce fewer wet diapers and fewer tears. Changes in alertness range from irritability or reduced activity to lethargy and impaired consciousness as depletion becomes severe. These findings are interpreted together rather than treating any single sign as a reliable measure of severity. In children, an accurately measured loss of approximately 10% or more of pre-illness body weight is generally classified as severe dehydration, although clinical estimates are less precise when a recent baseline weight is unavailable. (niddk.nih.gov)\n\nFluid depletion also disrupts electrolyte and acid–base balance. Diarrheal losses of bicarbonate predispose to metabolic acidosis, whereas substantial loss of gastric acid through vomiting can produce metabolic alkalosis. Potassium depletion may cause hypokalemia; serum sodium may rise or fall depending on the relative losses of water and sodium and the composition of replacement fluids. Progressive depletion produces tachycardia, hypotension, and ultimately hypovolemic circulatory shock with impaired tissue perfusion. Reduced blood flow to the kidneys can cause acute kidney injury, adding impaired filtration to the reduced urine output associated with fluid conservation. Shock, organ damage, coma, and death are possible consequences of severe dehydration. (merckmanuals.com)\n\nHemolytic uremic syndrome (HUS) is a distinct complication of some Shiga-toxin-producing Escherichia coli infections, including O157:H7, rather than simply a consequence of fluid depletion. Shiga toxin can injure vascular endothelial cells, and the resulting thrombotic microangiopathy is characterized by red-cell destruction, a low platelet count, and acute kidney injury. Pallor, unexplained bruising, blood in the urine, and reduced urine output may accompany its development. Children younger than five years are particularly susceptible to HUS following O157:H7 infection. Although many affected people recover, the syndrome can cause permanent kidney damage or death; dehydration-related kidney injury and toxin-associated HUS therefore represent different mechanisms of renal complications. (pubmed.ncbi.nlm.nih.gov)\n\nIntestinal infection can also cause temporary lactose malabsorption by damaging the small-intestinal lining and reducing production of lactase, the enzyme that breaks down lactose. Unabsorbed lactose reaches the colon, where bacterial fermentation produces gas and fluid, contributing to bloating, abdominal discomfort, and further diarrhea. This secondary lactase deficiency can improve as the intestinal lining recovers. Lactose malabsorption describes impaired absorption, whereas lactose intolerance denotes the symptoms it produces; neither is equivalent to milk allergy. (niddk.nih.gov)\n\nReactive arthritis is an inflammatory complication associated with enteric infections caused by Salmonella, Shigella, Campylobacter, and Yersinia. Symptoms typically begin one to six weeks after infection, often after the diarrheal illness has resolved. Pain and swelling commonly affect the knees or ankles, sometimes accompanied by inflammation of the eyes or urinary tract. Only a small proportion of infected people develop this condition. The HLA-B27 genetic marker is associated with greater susceptibility and more persistent or severe disease, but is not required for its occurrence. Symptoms may resolve within weeks or months, while some cases become chronic. (niams.nih.gov)\n\nPostinfectious irritable bowel syndrome is another recognized outcome of enteric infection, involving persistent bowel symptoms after the acute illness. The Infectious Diseases Society of America’s 2017 guideline estimated that postinfectious functional gastrointestinal disorders, including this syndrome, occur in approximately 3–10% of adults following bacterial diarrhea. This estimate concerns a defined post-bacterial population, not all episodes of gastroenteritis. Symptoms often resolve within a year but can persist for several years; continued symptoms therefore do not necessarily indicate continued infection. (idsociety.org)"
    },
    {
      "heading": "Clinical assessment and differential diagnosis",
      "text": "Clinical assessment documents the onset and duration of vomiting and diarrhea, stool frequency and appearance, fluid intake, urine output, and the location and progression of abdominal pain. Exposure history includes shared meals, untreated water, recent travel, contact with people with similar symptoms, animal contact, and residence or employment in institutional settings. Several people becoming ill after the same meal supports a common exposure, whereas illness among household contacts may indicate person-to-person transmission; neither pattern identifies a pathogen by itself. Symptoms persisting for at least 14 days broaden the assessment beyond an uncomplicated acute infection to include parasitic disease and noninfectious intestinal disorders. (niddk.nih.gov)\n\nPhysical examination assesses hydration and circulation alongside abdominal findings. Temperature, heart rate, respiratory rate, blood pressure, mental status, peripheral pulses, and capillary refill help characterize illness severity. Oral dryness, sunken eyes, reduced skin turgor, and reduced urine output contribute to the hydration assessment. In children, NICE’s 2009 guideline distinguishes clinical dehydration from shock: tachycardia and reduced skin turgor can accompany dehydration, while weak pulses, prolonged capillary refill, cold extremities, and hypotension indicate circulatory compromise. Blood pressure may remain normal before decompensated shock develops. Abdominal examination records distension, bowel sounds, tenderness, and whether pain is diffuse or localized; rebound tenderness is not a typical feature of uncomplicated gastroenteritis. (nice.org.uk)\n\nBloody or mucoid stool suggests inflammatory intestinal disease but does not distinguish infection from noninfectious colitis. The 2017 Infectious Diseases Society of America guideline identifies diarrhea accompanied by fever, severe abdominal cramping or tenderness, bloody stool, or signs of sepsis as a presentation requiring targeted investigation. High fever and systemic illness broaden concern to invasive infection or another infectious focus. Conversely, absence of fever does not exclude significant bacterial disease: Shiga-toxin-producing Escherichia coli may produce bloody diarrhea and marked abdominal tenderness with little or no fever. These findings guide the scope of diagnostic investigation rather than establishing a cause from symptoms alone. (idsociety.org)\n\nAppendicitis may initially resemble gastroenteritis because vomiting, fever, and sometimes diarrhea accompany abdominal pain. Pain beginning near the umbilicus and subsequently localizing to the right lower quadrant favors appendicitis, although the classic sequence is not universal. Yersinia enterocolitica infection can itself produce right-lower-quadrant pain resembling appendicitis. Bowel obstruction is another important alternative when vomiting occurs with abdominal distension, cramping, constipation, or difficulty passing gas. Partial obstruction may still produce diarrhea, so passage of loose stool does not exclude it. Bilious vomiting, severe localized pain, or rebound tenderness shifts assessment away from a presumptive diagnosis of uncomplicated gastroenteritis and toward structural or surgical disease. (niddk.nih.gov)\n\nPersistent or recurrent diarrhea, weight loss, and a personal or family history of intestinal disease broaden the differential to inflammatory bowel disease, including Crohn’s disease and ulcerative colitis, as well as celiac disease and food intolerance. Medication review includes prescription drugs, over-the-counter preparations, and their timing relative to symptom onset. Magnesium-containing antacids, antibiotics, and some anticancer medicines can cause diarrhea without establishing infectious gastroenteritis. Antibiotic exposure within the preceding three months specifically raises suspicion for Clostridioides difficile infection; recent healthcare exposure is another relevant clue. The temporal association with a medicine is therefore interpreted alongside stool characteristics, systemic findings, and exposure history rather than treated as proof of a single diagnosis. (niddk.nih.gov)"
    },
    {
      "heading": "Laboratory diagnosis and interpretation",
      "text": "Stool testing is selective rather than routine in uncomplicated, self-limited illness. The 2017 Infectious Diseases Society of America guideline identifies fever, bloody or mucoid stools, severe abdominal tenderness, and signs of sepsis as indications for bacterial investigation. Persistent illness, impaired immunity, and suspected outbreaks broaden the investigation; travelers with diarrhea lasting at least 14 days are evaluated for intestinal parasites. Outbreak-associated testing may include additional organisms according to public-health guidance. A diarrheal stool specimen—one that takes the shape of its container—is the preferred sample. (idsociety.org)\n\nStool culture recovers viable bacteria and supplies isolates for antimicrobial susceptibility testing and public-health characterization. For Shiga-toxin-producing Escherichia coli, investigation combines culture for O157 with assays detecting Shiga toxin or its genes, thereby covering non-O157 strains as well. Antigen assays detect organism-associated proteins rather than growing the organism. Enzyme immunoassays and rapid immunochromatographic tests are available for organisms such as Giardia and Cryptosporidium; direct fluorescent antibody assays identify labeled parasites microscopically. These methods differ in specimen requirements and analytical sensitivity, so they are not interchangeable. (idsociety.org)\n\nMicroscopic examination detects parasite stages, including cysts, trophozoites, and oocysts, but requires skilled interpretation. Concentration procedures and appropriate stains improve detection; Cryptosporidium, for example, can be identified using modified acid-fast staining. Targeted antigen testing offers a less labor-intensive alternative to morphological examination. Intermittent shedding also affects sampling: CDC specifies three stool specimens collected over several days for accurate Giardia testing, rather than treating a single negative specimen as definitive exclusion. (cdc.gov)\n\nNucleic-acid amplification, commonly using polymerase chain reaction, identifies pathogen genetic material without requiring culture. Multiplex gastrointestinal panels test simultaneously for several bacterial, viral, and parasitic targets; some integrated systems produce results in approximately one hour. Their breadth and sensitivity do not make every positive result causal: genetic material can be detected without demonstrating viable organisms, and multiple detections require interpretation alongside symptoms and exposure history. Molecular testing also does not automatically supply an isolate for susceptibility testing or outbreak comparison, so positive bacterial findings sometimes require follow-up culture. (asm.org)\n\nClostridioides difficile illustrates the distinction between detecting an organism and establishing disease. Molecular assays identify a toxin-producing strain but may also be positive in colonized individuals whose diarrhea has another cause. Glutamate dehydrogenase antigen testing detects the organism but is nonspecific for toxin-mediated disease; laboratories therefore combine it with toxin assays or molecular testing in multistep algorithms. Toxin enzyme immunoassays detect toxins A and/or B directly but are less sensitive than molecular assays. Handling matters: toxin can become undetectable within two hours at room temperature, producing false-negative results if specimens are not tested promptly or refrigerated. (cdc.gov)\n\nBlood tests assess complications rather than routinely identifying the enteric cause. In diagnosed Shiga-toxin-producing infection, serial hemoglobin, platelet, electrolyte, blood urea nitrogen, and creatinine measurements help detect developing hematologic and renal abnormalities; a blood smear assesses red-cell fragmentation when hemolytic uremic syndrome is suspected. Blood cultures address possible bloodstream infection and are indicated in suspected septicemia or enteric fever, with additional indications including systemic infection, immunocompromised hosts, and infants younger than three months. (idsociety.org)"
    },
    {
      "heading": "Fluid replacement and nutritional management",
      "text": "Oral rehydration therapy exploits intestinal sodium–glucose cotransport, which generally remains functional during infectious diarrhea even when other absorptive processes are impaired or intestinal secretion is increased. Coupled uptake of sodium and glucose promotes water absorption, allowing oral rehydration solution (ORS) to replace fluid and electrolyte losses without stopping the diarrhea itself. Reduced-osmolarity ORS is the first-line replacement fluid for mild to moderate dehydration in infants, children, and adults in the Infectious Diseases Society of America’s 2017 guideline. The WHO reduced-osmolarity formulation contains sodium and glucose at 75 mmol/L each, with a total osmolarity of 245 mOsm/L. Its balanced composition distinguishes it from plain water and sugar-rich beverages, which do not provide equivalent electrolyte replacement. (idsociety.org)\n\nOral and nasogastric delivery both use the intestinal absorptive pathway. In clinical care, small, repeated oral amounts can improve tolerance when vomiting occurs; vomiting alone does not necessarily make enteral rehydration ineffective. A nasogastric tube permits controlled delivery of ORS when a patient cannot drink adequately, including selected children who refuse fluids or are too weak to drink but retain normal mental status. Intravenous isotonic fluids, such as normal saline or lactated Ringer’s solution, are used for severe dehydration, circulatory shock, altered mental status, ileus, or failure of enteral replacement. Intravenous and oral therapy are not mutually exclusive: after circulation and mental status recover and enteral intake becomes safe, ORS can replace the remaining deficit and continuing losses. (idsociety.org)\n\nFluid management distinguishes correction of the existing deficit from subsequent maintenance requirements and replacement of ongoing stool and vomit losses. Restoration of nutrition proceeds alongside this process rather than waiting for diarrhea to cease. Breastfeeding continues throughout the diarrheal episode, including initial rehydration. Other age-appropriate foods are resumed during or immediately after rehydration, according to tolerance. Formula-fed infants generally return to their usual full-strength formula rather than a progressively diluted preparation. Routine lactose exclusion is unnecessary for most children, although clinically significant postinfectious lactose malabsorption can justify temporary dietary modification. Prolonged fasting and restrictive “BRAT” diets—bananas, rice, applesauce, and toast—provide inadequate nutritional variety and can delay nutritional recovery; normal diets supply energy and protein needed to replace illness-associated losses. (idsociety.org)\n\nPediatric zinc supplementation is an adjunct to rehydration and feeding, not a substitute for either. Its place in diarrheal-disease management depends on nutritional status, population context, and the guideline being applied. The 2017 IDSA guideline identifies benefit particularly in children aged six months to five years living in countries with a high prevalence of zinc deficiency or showing signs of malnutrition. The World Health Organization guideline published on December 31, 2024, provides broader recommendations for adjunctive oral zinc in children up to ten years of age with acute watery or persistent diarrhea. These recommendations concern pediatric diarrheal syndromes rather than every cause of gastroenteritis or routine adult treatment. Zinc’s principal measured benefit is shortening illness duration; it does not directly correct the fluid deficit that determines the need for oral, nasogastric, or intravenous replacement. (idsociety.org)"
    },
    {
      "heading": "Antimicrobial and symptom-directed treatment",
      "text": "Supportive care—principally fluid replacement and continued nutrition—remains the foundation of treatment, whereas pathogen-directed drugs are reserved for infections in which a clinical benefit is established. Antibiotics act against bacterial targets and do not treat viral gastroenteritis. The Infectious Diseases Society of America’s (IDSA) 2017 guideline generally discourages empirical antibiotics for acute watery diarrhea without recent international travel; exceptions include selected immunocompromised patients and ill-appearing young infants. Symptom-relieving medicines are adjuncts, not substitutes for correction of fluid and electrolyte losses. (medlineplus.gov)\n\nAntibacterial treatment depends on the organism, severity, host risk, and antimicrobial susceptibility. IDSA lists azithromycin for indicated treatment of Campylobacter infection and azithromycin, ciprofloxacin, or ceftriaxone as options for shigellosis, subject to susceptibility results. Uncomplicated nontyphoidal Salmonella gastroenteritis usually receives supportive care alone: antibiotics generally do not shorten diarrhea or fever in otherwise healthy people and can prolong asymptomatic bacterial carriage. Treatment is instead considered for severe or extraintestinal infection and patients at increased risk of invasive disease, including infants and immunosuppressed people. Antimicrobial stewardship includes restricting treatment to appropriate indications and modifying or discontinuing empirical therapy when a clinically plausible pathogen is identified, thereby limiting adverse effects and selection for antibiotic resistance. (idsociety.org)\n\nShiga-toxin-producing Escherichia coli (STEC) is an important exception to the assumption that bacterial diarrhea warrants antibiotics. Antibiotic exposure can increase the risk of hemolytic uremic syndrome, a complication involving hemolytic anemia, reduced platelets, and kidney injury. IDSA specifically recommends avoiding antimicrobial treatment for STEC O157 and strains producing Shiga toxin 2, including cases in which the toxin genotype is unknown. Antimotility medicines are also avoided in STEC infection because they may increase complications. Bloody diarrhea therefore does not, by itself, establish an indication for antibacterial treatment. (idsociety.org)\n\nAntiparasitic therapy is likewise organism-specific. Giardia infection can be treated with tinidazole, metronidazole, or nitazoxanide; Cyclospora infection is treated with trimethoprim–sulfamethoxazole. Invasive Entamoeba histolytica infection requires metronidazole or tinidazole followed by a luminal agent, such as paromomycin, to eliminate intestinal organisms remaining after tissue-directed treatment. Nitazoxanide is approved in the United States for cryptosporidiosis in immunocompetent patients aged at least one year, but its effectiveness in people with weakened immunity is unclear. In HIV-associated cryptosporidiosis, antiretroviral treatment can improve disease control through immune restoration. (cdc.gov)\n\nSymptom-directed drugs have age- and disease-specific limitations. Ondansetron, a serotonin \\(5\\text{-HT}_3\\)-receptor antagonist, suppresses vomiting and can facilitate oral rehydration. Canadian Paediatric Society guidance supports selected emergency-department use in children aged six months or older with dehydration or failed oral rehydration; diarrhea is a recognized adverse effect, and cardiac rhythm risks require consideration. Loperamide reduces intestinal motility and can lessen acute watery diarrhea in immunocompetent adults. IDSA advises against its use in children under 18 with acute diarrhea and in inflammatory diarrhea or diarrhea with fever because of risks including ileus and toxic megacolon; CDC also advises avoiding antimotility agents in bloody diarrhea. (cps.ca)\n\nEvidence for probiotics cannot be generalized across strains or preparations. A 2018 randomized controlled trial led by David Schnadower enrolled 971 children aged three months to four years at ten United States pediatric emergency departments. Moderate-to-severe gastroenteritis developed in 11.8% of evaluable recipients of Lactobacillus rhamnosus GG and 12.6% of placebo recipients, with no significant improvement in diarrhea duration or other major outcomes. Although IDSA’s 2017 guideline allowed probiotic use with a weak recommendation, the American Gastroenterological Association’s 2020 guideline recommended against probiotics for acute infectious gastroenteritis in children. These findings distinguish an established supportive treatment, rehydration, from supplements whose routine benefit is not demonstrated for the tested population and formulation. (nejm.org)"
    },
    {
      "heading": "Prevention and vaccination",
      "text": "Safe drinking water, sanitation, and hygiene reduce exposure to enteric pathogens by interrupting the passage of fecal material into water, food, and hands. Population-level measures include protection and treatment of water supplies, safe household water storage, and sanitation systems that contain human waste. Their effectiveness depends on both infrastructure and reliable access: an improved water source can still become contaminated during transport or storage. The World Health Organization (WHO), in its March 2024 diarrhoeal-disease fact sheet, identifies safe water, improved sanitation, handwashing with soap, food hygiene, breastfeeding, and rotavirus vaccination as complementary preventive measures. These measures address broader diarrhoeal disease rather than gastroenteritis alone. (who.int)\n\nFood-handling controls interrupt contamination and limit microbial multiplication before consumption. WHO’s Five Keys to Safer Food, introduced in 2001, organize these controls into cleanliness, separation of raw and cooked foods, thorough cooking, safe storage temperatures, and safe water and ingredients. Separate utensils and containers prevent juices from raw meat or seafood from contaminating ready-to-eat foods; refrigeration and hot holding constrain the growth of many microorganisms. Hand hygiene is particularly important after toilet use or diaper changing and before food preparation. For norovirus, CDC emphasizes washing with soap and water for at least 20 seconds because alcohol-based hand sanitizer alone does not work well against the virus. Food-service exclusion policies also reduce contamination by infected workers: CDC specifies exclusion during illness and for at least 48 hours after symptoms resolve, although fecal shedding can continue beyond that interval. (iris.who.int)\n\nEnvironmental cleaning and disinfection perform different functions. Cleaning removes fecal material, vomit, and other soil, whereas disinfection inactivates pathogens remaining on a surface. CDC’s healthcare guidance specifies cleaning before disinfectant application and attention to frequently touched objects, including toilets, faucets, door handles, and shared equipment. For norovirus-contaminated areas, its public guidance identifies chlorine solutions containing 1,000–5,000 parts per million or products registered by the United States Environmental Protection Agency as effective against norovirus. Product-specific application and contact times matter; a surface that has merely been wiped is not necessarily disinfected. Careful handling and laundering of contaminated clothing and bedding provide an additional barrier to environmental transmission. (cdc.gov)\n\nRotavirus vaccines specifically prevent rotavirus disease, especially severe childhood gastroenteritis; they do not provide general protection against norovirus, bacterial infections, or parasitic causes. The orally administered products RotaTeq and Rotarix were licensed in the United States in 2006 and 2008, respectively. CDC reports 85–98% protection against severe rotavirus illness and hospitalization during an infant’s first year, compared with 74–87% protection against illness of any severity. WHO’s July 2021 position-paper summary reports trial efficacy against severe rotavirus gastroenteritis of approximately 90–95% in low-child-mortality settings and 44–70% in high-child-mortality settings over one or two years of follow-up. Despite lower relative efficacy in high-mortality settings, the larger underlying disease burden means vaccination can avert substantial numbers of severe cases and deaths. WHO therefore supports inclusion in national immunization programmes, particularly where rotavirus-associated fatality rates are high. (cdc.gov)\n\nBreastfeeding is another protective factor in childhood diarrhoeal disease. Breast milk supplies antibodies and other protective components, while exclusive breastfeeding reduces exposure to potentially contaminated supplemental water and foods. WHO includes exclusive breastfeeding during the first six months among population-level preventive measures, and UNICEF emphasizes its importance where clean water and hygienic feeding conditions are disrupted. Protection is not absolute and does not replace vaccination, sanitation, or food-safety controls. The evidence and policy framework concern childhood diarrhoeal disease broadly, rather than complete protection against every pathogen capable of causing gastroenteritis. (who.int)"
    },
    {
      "heading": "Surveillance and outbreak investigation",
      "text": "Outbreak investigations use a standardized case definition to determine which illnesses belong to a cluster. The definition combines clinical features, such as vomiting or diarrhea, with a specified onset period, location, and population; laboratory findings may distinguish confirmed cases from clinically compatible cases. Definitions can be refined as evidence accumulates. For foodborne surveillance, the US Centers for Disease Control and Prevention (CDC) defines an outbreak as two or more people experiencing similar illness after ingesting a common food. Investigators compile a line list of cases, including symptom onset, exposures, laboratory results, and outcomes, so that cases can be compared consistently by person, place, and time. (cdc.gov)\n\nExposure interviews reconstruct meals, drinking-water sources, travel, events, and relevant contacts during the period preceding illness. The interval investigated depends on the suspected pathogen’s incubation period. Receipts, purchase records, and repeat interviews can clarify exposures that patients do not initially remember, particularly ingredients hidden within prepared dishes. An epidemic curve plots cases by symptom-onset time: a concentrated peak can suggest a brief common-source exposure, whereas successive waves may suggest person-to-person transmission. These patterns generate hypotheses rather than establish a cause. At a shared meal, a retrospective cohort study can compare the proportion becoming ill among people who ate each item with the proportion among those who did not; case–control studies provide another method for testing suspected exposures. (cdc.gov)\n\nLaboratory testing is coordinated with epidemiological and environmental investigation. Clinical specimens establish the agent circulating among patients, while implicated foods, water, or environmental samples can help identify the vehicle or contamination point. CDC’s 2011 norovirus outbreak-management guidance specifies collection of whole-stool specimens from at least five affected people during the acute phase, preferably within 72 hours of onset, for real-time reverse-transcription polymerase chain reaction testing and subsequent genotyping. Routine environmental swabbing is not required for institutional norovirus outbreaks, but targeted sampling can investigate a source supported by exposure evidence. Finding a matching pathogen in food strengthens attribution only when epidemiological evidence also links patients to that food. Conversely, a negative food test does not exclude contamination: the consumed product may be unavailable, or contamination may have affected only an unsampled portion. Supply-chain traceback can identify a common producer or distributor across otherwise separate exposure locations. (cdc.gov)\n\nOrganized public health surveillance links local investigations to broader patterns. CDC’s National Outbreak Reporting System (NORS), launched in 2009, receives reports from US local, state, and territorial health departments on foodborne and waterborne outbreaks and enteric outbreaks transmitted through infected people, animals, environmental sources, or unknown routes. CaliciNet, also launched in 2009, collects norovirus strain information from outbreaks, complementing epidemiological reports with molecular data. The Norovirus Sentinel Testing and Tracking network (NoroSTAT), established in August 2012, introduced reporting through NORS and CaliciNet within seven business days of notification to participating state health departments. These systems monitor outbreak activity rather than enumerate every infection; individual norovirus cases are not required to be reported to CDC. (cdc.gov)\n\nInstitutional control measures begin while source investigation continues. CDC’s healthcare norovirus guidance combines active case-finding and prompt notification with isolation or cohorting of symptomatic patients, staff assignment to designated cohorts, enhanced cleaning, and exclusion of ill personnel. Contact precautions continue for at least 48 hours after symptoms resolve; affected staff are excluded for at least 48 hours after resolution. Depending on the outbreak, facilities may restrict patient movement, suspend communal activities, or close affected wards to new admissions. Ongoing onset-date records allow investigators to assess whether transmission continues after these measures and to distinguish new introductions from spread within the institution. (cdc.gov)"
    },
    {
      "heading": "Historical development of understanding and control",
      "text": "Before specific enteric viruses could be identified, many outbreaks were classified as “nonbacterial gastroenteritis”: a description of illness for which bacterial investigations had not established a cause, rather than a single etiological diagnosis. The discovery of distinct viral agents in the 1970s transformed this category. Electron microscopy was particularly important because it could reveal particles that conventional culture methods had failed to detect. For childhood diarrhea, the diagnostic gap was substantial: before rotavirus was discovered, bacterial, viral, or parasitic causes could be identified in only about 10–30% of cases in the studies summarized by CDC’s historical review. (wwwnc.cdc.gov)\n\nThe Norwalk outbreak and the identification of its agent were separate events. An outbreak of acute gastroenteritis occurred at an elementary school in Norwalk, Ohio, in 1968; in 1972, Albert Z. Kapikian and colleagues reported a 27-nanometer particle in infectious stool material derived from that outbreak. Their technique, immune electron microscopy, used antibodies to coat and aggregate particles, making a small, relatively inconspicuous agent easier to recognize. Antibody responses in naturally infected patients and experimentally infected volunteers supported the association between the particle and illness. The agent became known as Norwalk virus, the prototype of the viruses subsequently classified as noroviruses. (pmc.ncbi.nlm.nih.gov)\n\nA distinct discovery followed in 1973, when Ruth Bishop, Geoffrey Davidson, Ian Holmes, and Brian Ruck investigated children with acute nonbacterial gastroenteritis at the Royal Children’s Hospital in Melbourne. Electron microscopy of duodenal biopsies revealed viral particles in intestinal epithelial cells in six of nine children examined. The agent was subsequently named rotavirus because of its wheel-like appearance. Detection in stool subsequently allowed laboratories to investigate infection without intestinal biopsy; within five years, rotavirus was recognized as a leading worldwide cause of severe diarrhea in infants and young children. (sciencedirect.com)\n\nMolecular methods changed norovirus investigation in the early 1990s. In 1992, Xi Jiang, Jianxiang Wang, David Y. Graham, and Mary K. Estes described reverse-transcription polymerase chain reaction for detecting Norwalk virus in stool. The method converted viral RNA into complementary DNA and amplified selected sequences; in their experiments, it was approximately 100 times more sensitive than dot-blot hybridization. Application to outbreak specimens in 1994 demonstrated that related viruses could be detected and their amplified sequences compared. These developments made laboratory attribution more sensitive while revealing genetic diversity that complicated assays designed around the original Norwalk strain. (journals.asm.org)\n\nControl of dehydration advanced independently of pathogen identification. In 1968, David Nalin, Richard Cash, and colleagues demonstrated oral maintenance therapy for cholera in what was then East Pakistan, now Bangladesh. Glucose–electrolyte solutions exploited preserved intestinal sodium–glucose absorption, permitting water uptake despite continuing diarrhea; oral maintenance reduced intravenous-fluid requirements by approximately 80% in adult cholera studies. WHO and UNICEF adopted oral rehydration therapy in the late 1970s. In 2002, the World Health Organization recommended a reduced-osmolarity formulation. Compared with the earlier solution’s 311 mOsm/L, the new formulation had an osmolarity of 245 mOsm/L, with sodium and glucose each at 75 mmol/L; trials supported reductions in stool output, vomiting, and unscheduled intravenous infusions. (iris.who.int)\n\nRotavirus vaccination introduced pathogen-specific prevention of severe childhood gastroenteritis. RotaShield, the first rotavirus vaccine licensed in the United States, entered use in 1998 but was withdrawn in 1999 after postmarketing surveillance identified an association with intussusception, a form of intestinal obstruction. Second-generation oral vaccines followed: RotaTeq was licensed in the United States in 2006 and Rotarix in 2008. These milestones linked the earlier identification of a major childhood pathogen to preventive immunization, while the RotaShield experience demonstrated the importance of safety monitoring after licensure. (cdc.gov)"
    }
  ],
  "links": [
    "diarrhea",
    "nausea",
    "abdominal-pain",
    "virus",
    "bacteria",
    "influenza",
    "electrolyte",
    "public-health",
    "inflammation",
    "stomach",
    "world-health-organization",
    "public-health-surveillance",
    "fever",
    "vaccine",
    "appendicitis",
    "escherichia-coli",
    "cholera",
    "immunodeficiency",
    "hiv-aids",
    "infectious-disease",
    "water",
    "osmosis",
    "homeostasis",
    "diagnosis",
    "kidney",
    "immune-system",
    "sepsis",
    "inflammatory-bowel-disease",
    "polymerase-chain-reaction",
    "blood-test",
    "glucose",
    "nutrition",
    "antibiotic-resistance",
    "randomized-controlled-trial",
    "infrastructure",
    "microorganism",
    "epidemiology"
  ],
  "sources": [
    {
      "title": "Overview of Gastroenteritis - Merck Manual Professional Edition",
      "url": "https://www.merckmanuals.com/professional/gastrointestinal-disorders/gastroenteritis/overview-of-gastroenteritis"
    },
    {
      "title": "Definition & Facts for Viral Gastroenteritis (“Stomach Flu”) - NIDDK",
      "url": "https://www.niddk.nih.gov/health-information/digestive-diseases/viral-gastroenteritis/definition-facts"
    },
    {
      "title": "Definition & Facts for Diarrhea - NIDDK",
      "url": "https://www.niddk.nih.gov/health-information/digestive-diseases/diarrhea/definition-facts?dkrd=www2.niddk.nih.gov"
    },
    {
      "title": "Gastritis & Gastropathy - NIDDK",
      "url": "https://www.niddk.nih.gov/health-information/digestive-diseases/gastritis-gastropathy"
    },
    {
      "title": "Definition of colitis - NCI Dictionary of Cancer Terms",
      "url": "https://www.cancer.gov/publications/dictionaries/cancer-terms/def/colitis"
    },
    {
      "title": "Definition of radiation enteritis - NCI Dictionary of Cancer Terms",
      "url": "https://www.cancer.gov/publications/dictionaries/cancer-terms/def/radiation-enteritis"
    },
    {
      "title": "Definition & Facts of Food Poisoning - NIDDK",
      "url": "https://www.niddk.nih.gov/health-information/digestive-diseases/food-poisoning/definition-facts"
    },
    {
      "title": "Clinical Overview of Botulism - CDC",
      "url": "https://www.cdc.gov/botulism/hcp/clinical-overview/"
    },
    {
      "title": "Diarrhoeal disease",
      "url": "https://www.who.int/en/news-room/fact-sheets/detail/diarrhoeal-disease"
    },
    {
      "title": "Global, regional, and national age-sex-specific burden of diarrhoeal diseases, their risk factors, and aetiologies, 1990–2021, for 204 countries and territories: a systematic analysis for the Global Burden of Disease Study 2021",
      "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC12018300/"
    },
    {
      "title": "Norovirus Disease in the United States",
      "url": "https://wwwnc.cdc.gov/eid/article/19/8/13-0465_article"
    },
    {
      "title": "Norovirus Facts and Stats",
      "url": "https://www.cdc.gov/norovirus/data-research/index.html?ftag=YHF4eb9d17"
    },
    {
      "title": "Chapter 19: Rotavirus",
      "url": "https://www.cdc.gov/pinkbook/hcp/table-of-contents/chapter-19-rotavirus.html?CDC_AAref_Val=https%3A%2F%2Fwww.cdc.gov%2Fvaccines%2Fpubs%2Fpinkbook%2Frota.html"
    },
    {
      "title": "Trends in the Laboratory Detection of Rotavirus Before and After Implementation of Routine Rotavirus Vaccination — United States, 2000–2018",
      "url": "https://www.cdc.gov/mmwr/volumes/68/wr/mm6824a2.htm"
    },
    {
      "title": "Clinical Overview of Rotavirus",
      "url": "https://www.cdc.gov/rotavirus/hcp/clinical-overview/index.html"
    },
    {
      "title": "Surveillance Summaries",
      "url": "https://www.cdc.gov/mmwr/pdf/ss/ss6412.pdf"
    },
    {
      "title": "Symptoms & Causes of Viral Gastroenteritis (“Stomach Flu”) - NIDDK",
      "url": "https://www.niddk.nih.gov/health-information/digestive-diseases/viral-gastroenteritis/symptoms-causes"
    },
    {
      "title": "About Norovirus",
      "url": "https://www.cdc.gov/norovirus/about/index.html"
    },
    {
      "title": "Norovirus — CDC Yellow Book",
      "url": "https://www.cdc.gov/yellow-book/hcp/travel-associated-infections-diseases/norovirus.html"
    },
    {
      "title": "Rotavirus Vaccine Recommendations",
      "url": "https://www.cdc.gov/rotavirus/hcp/vaccine-considerations/index.html"
    },
    {
      "title": "Non-Norovirus Viral Gastroenteritis Outbreaks Reported to the National Outbreak Reporting System, USA, 2009–2018",
      "url": "https://wwwnc.cdc.gov/eid/article/27/2/20-3943_article"
    },
    {
      "title": "HAN Archive — 00462",
      "url": "https://archive.cdc.gov/www_cdc_gov/han/2022/han00462.html"
    },
    {
      "title": "Comprehensive Review of Human Sapoviruses",
      "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC4284302/"
    },
    {
      "title": "IDSA 2017 Clinical Practice Guidelines for the Diagnosis and Management of Infectious Diarrhea",
      "url": "https://www.idsociety.org/practice-guideline/infectious-diarrhea"
    },
    {
      "title": "Laboratory Methods for the Diagnosis of Epidemic Dysentery and Cholera",
      "url": "https://www.cdc.gov/cholera/media/pdfs/2024/07/Chapter-1-Laboratory-methods-for-the-diagnosis-of-epidemic-dysentery-and-cholera_ENG.pdf"
    },
    {
      "title": "Confirming an Etiology in Foodborne Outbreaks",
      "url": "https://www.cdc.gov/foodborne-outbreaks/php/confirming-cause/?CDC_AAref_Val=https%3A%2F%2Fwww.cdc.gov%2Ffoodsafety%2Foutbreaks%2Finvestigating-outbreaks%2Fconfirming_diagnosis.html"
    },
    {
      "title": "Clinical Overview of Campylobacter",
      "url": "https://www.cdc.gov/campylobacter/hcp/clinical-overview/index.html"
    },
    {
      "title": "Clinical Overview of Salmonellosis",
      "url": "https://www.cdc.gov/salmonella/hcp/clinical-overview/"
    },
    {
      "title": "Clinical Guidance for Typhoid Fever and Paratyphoid Fever",
      "url": "https://www.cdc.gov/typhoid-fever/hcp/clinical-guidance/index.html"
    },
    {
      "title": "Antimicrobial-Resistant Shigella spp. in San Diego, California, USA, 2017–2020",
      "url": "https://wwwnc.cdc.gov/eid/article/28/6/22-0131_article"
    },
    {
      "title": "About Yersinia Infection",
      "url": "https://www.cdc.gov/yersinia/about/index.html"
    },
    {
      "title": "Kinds of E. coli",
      "url": "https://www.cdc.gov/ecoli/about/kinds-of-ecoli.html"
    },
    {
      "title": "Cholera",
      "url": "https://www.cdc.gov/yellow-book/hcp/travel-associated-infections-diseases/cholera.html"
    },
    {
      "title": "Vibrio parahaemolyticus Foodborne Illness Associated with Oysters, Australia, 2021–2022",
      "url": "https://wwwnc.cdc.gov/eid/article/30/11/24-0172_article"
    },
    {
      "title": "What Causes Parasitic Diseases",
      "url": "https://www.cdc.gov/parasites/causes/index.html"
    },
    {
      "title": "CDC - DPDx - Giardiasis",
      "url": "https://www.cdc.gov/dpdx/giardiasis/index.html"
    },
    {
      "title": "Symptoms of Giardia Infection",
      "url": "https://www.cdc.gov/giardia/signs-symptoms/index.html"
    },
    {
      "title": "CDC - DPDx - Cryptosporidiosis",
      "url": "https://www.cdc.gov/dpdx/cryptosporidiosis/"
    },
    {
      "title": "Recommendations for Preventing and Controlling Cryptosporidiosis Outbreaks",
      "url": "https://stacks.cdc.gov/view/cdc/31782/cdc_31782_DS1.pdf"
    },
    {
      "title": "CDC - DPDx - Cyclosporiasis",
      "url": "https://www.cdc.gov/dpdx/cyclosporiasis/"
    },
    {
      "title": "Cyclosporiasis — Provider Fact Sheet",
      "url": "https://www.cdc.gov/parasites/cyclosporiasis/resources/pdf/cyclosporiasis_provider.pdf"
    },
    {
      "title": "CDC - DPDx - Amebiasis",
      "url": "https://www.cdc.gov/dpdx/amebiasis/"
    },
    {
      "title": "About Staph Food Poisoning",
      "url": "https://www.cdc.gov/staph-food-poisoning/about/"
    },
    {
      "title": "BAM: Quantitative Analysis for Cereulide in Food Products",
      "url": "https://www.fda.gov/food/laboratory-methods-food/bam-quantitative-analysis-cereulide-food-products"
    },
    {
      "title": "Outbreak of Staphylococcal Food Poisoning Associated with Precooked Ham -- Florida, 1997",
      "url": "https://www.cdc.gov/mmwr/preview/mmwrhtml/00050415.htm"
    },
    {
      "title": "Bacillus cereus",
      "url": "https://www.bfr.bund.de/de/bacillus_cereus-54345.html"
    },
    {
      "title": "Drug-Related Gastroenteritis and Chemical-Related Gastroenteritis",
      "url": "https://www.merckmanuals.com/en-ca/home/digestive-disorders/gastroenteritis/drug-related-gastroenteritis-and-chemical-related-gastroenteritis"
    },
    {
      "title": "Clinician Brief: Arsenic",
      "url": "https://www.atsdr.cdc.gov/environmental-medicine/hcp/clinician-briefs/arsenic.html"
    },
    {
      "title": "Arsenic Toxicity: Clinical Assessment",
      "url": "https://archive.cdc.gov/www_atsdr_cdc_gov/csem/arsenic/clinical_assessment.html"
    },
    {
      "title": "Symptoms & Causes of Diarrhea",
      "url": "https://www.niddk.nih.gov/health-information/digestive-diseases/diarrhea/symptoms-causes?dkrd=www2.niddk.nih.gov"
    },
    {
      "title": "Preventing Shigella Infection Among Young Children",
      "url": "https://www.cdc.gov/shigella/prevention/preventing-shigella-infection-among-young-children.html"
    },
    {
      "title": "How to Prevent Norovirus",
      "url": "https://www.cdc.gov/norovirus/prevention/index.html"
    },
    {
      "title": "Norovirus Fact Sheet for Food Workers",
      "url": "https://portugues.cdc.gov/norovirus/communication-resources/facts-for-food-workers.html"
    },
    {
      "title": "Norovirus Transmission on Cruise Ship",
      "url": "https://wwwnc.cdc.gov/eid/article/11/1/04-0434_article"
    },
    {
      "title": "General Information about Norovirus",
      "url": "https://archive.cdc.gov/www_cdc_gov/hai/organisms/norovirus.html"
    },
    {
      "title": "Preventing Diarrheal Illnesses",
      "url": "https://www.cdc.gov/healthy-swimming/prevention/preventing-diarrheal-illnesses.html"
    },
    {
      "title": "What to Do When There is Poop in the Pool",
      "url": "https://www.cdc.gov/healthy-swimming/response/what-to-do-when-there-is-poop-in-the-pool.html"
    },
    {
      "title": "About Campylobacter infection",
      "url": "https://www.cdc.gov/campylobacter/index.html"
    },
    {
      "title": "Multidrug-Resistant Campylobacter jejuni Outbreak Linked to Puppy Exposure — United States, 2016–2018",
      "url": "https://www.cdc.gov/mmwr/volumes/67/wr/mm6737a3.htm"
    },
    {
      "title": "Infectious diarrhea: Cellular and molecular mechanisms",
      "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC3035144/"
    },
    {
      "title": "Diarrhea in Adults - Digestive Disorders - Merck Manual Consumer Version",
      "url": "https://www.merckmanuals.com/home/digestive-disorders/symptoms-of-digestive-disorders/diarrhea-in-adults?media=full"
    },
    {
      "title": "Toxin Mediated Diarrhea in the 21st Century: The Pathophysiology of Intestinal Ion Transport in the Course of ETEC, V. cholerae and Rotavirus Infection",
      "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC3153279/"
    },
    {
      "title": "Rotavirus Stimulates Release of Serotonin (5-HT) from Human Enterochromaffin Cells and Activates Brain Structures Involved in Nausea and Vomiting",
      "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC3136449/"
    },
    {
      "title": "Symptoms of Salmonella Infection",
      "url": "https://www.cdc.gov/salmonella/signs-symptoms/index.html"
    },
    {
      "title": "Symptoms of Campylobacter Infection",
      "url": "https://www.cdc.gov/campylobacter/signs-symptoms/index.html"
    },
    {
      "title": "Managing Acute Gastroenteritis Among Children: Oral Rehydration, Maintenance, and Nutritional Therapy",
      "url": "https://www.cdc.gov/Mmwr/Preview/Mmwrhtml/rr5216a1.htm"
    },
    {
      "title": "NIH urges older Americans to protect their kidneys",
      "url": "https://www.nia.nih.gov/news/nih-urges-older-americans-protect-their-kidneys"
    },
    {
      "title": "Diarrhoea — Pocket Book of Hospital Care for Children",
      "url": "https://www.ncbi.nlm.nih.gov/books/NBK154434/"
    },
    {
      "title": "Malnutrition: Emergencies and disasters",
      "url": "https://www.who.int/news-room/questions-and-answers/item/malnutrition-emergencies-and-disasters"
    },
    {
      "title": "Dehydration in Children - Merck Manual Professional Edition",
      "url": "https://www.merckmanuals.com/professional/pediatrics/dehydration-and-fluid-therapy-in-children/dehydration-in-children"
    },
    {
      "title": "Clinical Practice Guideline: Acute Kidney Injury",
      "url": "https://renal.org/sites/renal.org/files/FINAL-AKI-Guideline.pdf"
    },
    {
      "title": "Direct cytotoxic action of Shiga toxin on human vascular endothelial cells",
      "url": "https://pubmed.ncbi.nlm.nih.gov/3044997/"
    },
    {
      "title": "Information for Clinicians | E. coli infection | CDC",
      "url": "https://www.cdc.gov/ecoli/hcp/guidance/index.html"
    },
    {
      "title": "Hemolytic Uremic Syndrome in Children - NIDDK",
      "url": "https://www.niddk.nih.gov/health-information/kidney-disease/children/hemolytic-uremic-syndrome"
    },
    {
      "title": "Signs of Hemolytic Uremic Syndrome - CDC",
      "url": "https://www.cdc.gov/ecoli/signs-symptoms/hus.html"
    },
    {
      "title": "Symptoms & Causes of Lactose Intolerance - NIDDK",
      "url": "https://www.niddk.nih.gov/health-information/digestive-diseases/lactose-intolerance/symptoms-causes?dkrd=www2.niddk.nih.gov"
    },
    {
      "title": "Reactive Arthritis - NIAMS",
      "url": "https://www.niams.nih.gov/health-topics/reactive-arthritis"
    },
    {
      "title": "Diagnosis of Diarrhea - NIDDK",
      "url": "https://www.niddk.nih.gov/health-information/digestive-diseases/diarrhea/diagnosis"
    },
    {
      "title": "Recommendations: Diarrhoea and vomiting caused by gastroenteritis in under 5s: diagnosis and management - NICE",
      "url": "https://www.nice.org.uk/guidance/cg84/chapter/Recommendations"
    },
    {
      "title": "Overview of Gastroenteritis - Merck Manual Professional Edition",
      "url": "https://www.merckmanuals.com/professional/gastrointestinal-disorders/gastroenteritis/overview-of-gastroenteritis?qt=amoebiasis"
    },
    {
      "title": "Symptoms & Causes of Appendicitis - NIDDK",
      "url": "https://www.niddk.nih.gov/health-information/digestive%20diseases/appendicitis/symptoms-causes"
    },
    {
      "title": "Definition of intestinal obstruction - NCI Dictionary of Cancer Terms",
      "url": "https://www.cancer.gov/publications/dictionaries/cancer-terms/def/intestinal-obstruction"
    },
    {
      "title": "CDC – DPDx – Stool Specimens: Detection of Parasite Antigens",
      "url": "https://www.cdc.gov/dpdx/diagnosticprocedures/stool/antigendetection.html"
    },
    {
      "title": "Clinical Testing and Diagnosis for Giardia Infection",
      "url": "https://www.cdc.gov/giardia/hcp/diagnosis-testing/index.html"
    },
    {
      "title": "Clinical Utility of Multiplex Tests for Respiratory and GI Pathogens",
      "url": "https://asm.org/guideline/clinical-utility-of-multiplex-tests-for-respirator"
    },
    {
      "title": "Clinical Testing and Diagnosis for C. diff Infection",
      "url": "https://www.cdc.gov/c-diff/hcp/diagnosis-testing/"
    },
    {
      "title": "Managing Acute Gastroenteritis Among Children: Oral Rehydration, Maintenance, and Nutritional Therapy",
      "url": "https://www.cdc.gov/mmwr/preview/mmwrhtml/rr5216a1.htm"
    },
    {
      "title": "Guideline on management of pneumonia and diarrhoea in children up to 10 years of age",
      "url": "https://www.who.int/publications/i/item/9789240103412"
    },
    {
      "title": "Guideline on management of pneumonia and diarrhoea in children up to 10 years of age",
      "url": "https://iris.who.int/bitstream/handle/10665/380059/9789240103412-eng.pdf?sequence=1"
    },
    {
      "title": "Viral gastroenteritis (stomach flu): MedlinePlus Medical Encyclopedia",
      "url": "https://medlineplus.gov/ency/article/000252.htm"
    },
    {
      "title": "Clinical Overview of Salmonellosis",
      "url": "https://www.cdc.gov/salmonella/hcp/clinical-overview/index.html"
    },
    {
      "title": "Treatment of E. coli Infection",
      "url": "https://www.cdc.gov/ecoli/treatment/index.html"
    },
    {
      "title": "Information for Clinicians",
      "url": "https://www.cdc.gov/ecoli/hcp/guidance/?CDC_AAref_Val=https%3A%2F%2Fwww.cdc.gov%2Fecoli%2Fclinicians.html"
    },
    {
      "title": "Patient Care for Giardia Infection",
      "url": "https://www.cdc.gov/giardia/hcp/clinical-care/index.html"
    },
    {
      "title": "Travelers’ Diarrhea",
      "url": "https://www.cdc.gov/yellow-book/hcp/preparing-international-travelers/travelers-diarrhea.html"
    },
    {
      "title": "Treating Crypto",
      "url": "https://www.cdc.gov/cryptosporidium/treatment/"
    },
    {
      "title": "Emergency department use of oral ondansetron for acute gastroenteritis-related vomiting in infants and children",
      "url": "https://cps.ca/en/documents/position/oral-ondansetron"
    },
    {
      "title": "AGA does not recommend the use of probiotics for most digestive conditions",
      "url": "https://gastro.org/press-releases/aga-does-not-recommend-the-use-of-probiotics-for-most-digestive-conditions/"
    },
    {
      "title": "Five keys to safer food manual",
      "url": "https://iris.who.int/bitstream/handle/10665/43546/9789241594639_eng.pdf?sequence=1"
    },
    {
      "title": "Five keys to safer food",
      "url": "https://www.who.int/docs/librariesprovider2/default-document-library/5keys_en.pdf"
    },
    {
      "title": "How to Prevent Norovirus",
      "url": "https://www.cdc.gov/norovirus/prevention/?CDC_AA_refVal=https%3A%2F%2Fwww.cdc.gov%2Fnorovirus%2Ffood-handlers%2Fwork-with-food.html"
    },
    {
      "title": "II. Summary of Recommendations",
      "url": "https://www.cdc.gov/infection-control/hcp/norovirus-guidelines/summary-recommendations.html"
    },
    {
      "title": "Summary of the WHO position paper on Rotavirus vaccines",
      "url": "https://cdn.who.int/media/docs/default-source/immunization/position_paper_documents/rotavirus/rotavirus-summary-23july-2021.pdf"
    },
    {
      "title": "Rotavirus vaccines: WHO position paper – July 2021",
      "url": "https://cdn.who.int/media/docs/default-source/immunization/position_paper_documents/rotavirus/wer9628-rotavirus-position-paper-2021.pdf?sfvrsn=e6593ed6_5"
    },
    {
      "title": "Why breastfeeding is critical for babies",
      "url": "https://www.unicef.org/stories/why-breastfeeding-best-babies"
    },
    {
      "title": "Conducting a Field Investigation",
      "url": "https://www.cdc.gov/field-epi-manual/php/chapters/field-investigation.html"
    },
    {
      "title": "Multistate Foodborne Outbreaks: Investigation Steps",
      "url": "https://www.cdc.gov/foodborne-outbreaks/outbreak-basics/investigation-steps.html"
    },
    {
      "title": "CDC LC Quick Learn: Using an Epi Curve to Determine Mode of Spread",
      "url": "https://www.cdc.gov/training/QuickLearns/epimode/"
    },
    {
      "title": "Updated Norovirus Outbreak Management and Disease Prevention Guidelines",
      "url": "https://www.cdc.gov/mmwr/preview/mmwrhtml/rr6003a1.htm"
    },
    {
      "title": "National Outbreak Reporting System (NORS)",
      "url": "https://www.cdc.gov/nors/index.html"
    },
    {
      "title": "National Outbreak Reporting System (NORS) Training Document: Integrated CDC Lab Systems",
      "url": "https://www.cdc.gov/nors/downloads/Lab-System-Training-Document-508.pdf"
    },
    {
      "title": "Effects and Clinical Significance of GII.4 Sydney Norovirus, United States, 2012–2013",
      "url": "https://wwwnc.cdc.gov/eid/article/19/8/13-0458_article"
    },
    {
      "title": "Norovirus Reporting and Surveillance",
      "url": "https://www.cdc.gov/norovirus/php/reporting/index.html"
    },
    {
      "title": "Rotavirus",
      "url": "https://wwwnc.cdc.gov/eid/article/4/4/98-0406_article"
    },
    {
      "title": "The Discovery of the 27-nm Norwalk Virus: An Historic Perspective",
      "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC7110248/"
    },
    {
      "title": "Rotavirus: discovery and vaccines",
      "url": "https://www.nhmrc.gov.au/about-us/resources/impact-case-studies/rotavirus-discovery-and-vaccines"
    },
    {
      "title": "Oral (or Nasogastric) Maintenance Therapy for Cholera Patients in all Age-groups",
      "url": "https://iris.who.int/bitstream/handle/10665/262462/PMC2427684.pdf?sequence=1"
    },
    {
      "title": "WHO/UNICEF Joint Statement",
      "url": "https://iris.who.int/bitstream/handle/10665/68627/WHO_FCH_CAH_04.7.pdf"
    },
    {
      "title": "Key family practices on child health care",
      "url": "https://www.emro.who.int/child-health/community-family/key-family-practices-on-child-health-care/All-Pages.html"
    }
  ],
  "license": "https://creativecommons.org/licenses/by/4.0/"
}