gastroenteritis gastroenteritis gastroenteritis, also known as infectious diarrhea and gastro, is an inflammation of the gastrointestinal tract including the stomach and intestine. symptoms may include diarrhea, vomiting, and abdominal pain. fever, lack of energy, and dehydration may also occur. this typically lasts less than two weeks. it is not related to influenza, even though in the u.s. it is sometimes called the "stomach flu". gastroenteritisother namesgastro, stomach bug, stomach virus, stomach flu, gastric flu, gastrointestinitisgastroenteritis viruses: a = rotavirus, b = adenovirus, c = norovirus and d = astrovirus. the virus particles are shown at the same magnification to allow size comparison.specialtyinfectious disease, gastroenterologysymptomsdiarrhea, vomiting, abdominal pain, fevercomplicationsdehydrationcausesviruses, bacteria, parasites, fungusdiagnostic methodbased on symptoms, occasionally stool culturedifferential diagnosisinflammatory bowel disease, malabsorption syndrome, lactose intolerancepreventionhand washing, drinking clean water, proper disposal of human waste, breastfeedingtreatmentoral rehydration solution (combination of water, salts, and sugar), intravenous fluidsfrequency2.4 billion (2015)deaths1.3 million (2015) gastroenteritis is usually caused by viruses; however, gut bacteria, parasites, and fungi can also cause gastroenteritis. in children, rotavirus is the most common cause of severe disease. in adults, norovirus and campylobacter are common causes. eating improperly prepared food, drinking contaminated water or close contact with a person who is infected can spread the disease. treatment is generally the same with or without a definitive diagnosis, so testing to confirm is usually not needed. for young children in impoverished countries, prevention includes hand washing with soap, drinking clean water, breastfeeding babies instead of using formula, and proper disposal of human waste. the rotavirus vaccine is recommended as a prevention for children. treatment involves getting enough fluids. for mild or moderate cases, this can typically be achieved by drinking oral rehydration solution (a combination of water, salts and sugar). in those who are breastfed, continued breastfeeding is recommended. for more severe cases, intravenous fluids may be needed. fluids may also be given by a nasogastric tube. zinc supplementation is recommended in children. antibiotics are generally not needed. however, antibiotics are recommended for young children with a fever and bloody diarrhea. in 2015, there were two billion cases of gastroenteritis, resulting in 1.3 million deaths globally. children and those in the developing world are affected the most. in 2011, there were about 1.7 billion cases, resulting in about 700,000 deaths of children under the age of five. in the developing world, children less than two years of age frequently get six or more infections a year. it is less common in adults, partly due to the development of immunity. signs and symptoms bristol stool chart gastroenteritis usually involves both diarrhea and vomiting. sometimes, only one or the other is present. this may be accompanied by abdominal cramps. signs and symptoms usually begin 12–72 hours after contracting the infectious agent. if due to a virus, the condition usually resolves within one week. some viral infections also involve fever, fatigue, headache and muscle pain. if the stool is bloody, the cause is less likely to be viral and more likely to be bacterial. some bacterial infections cause severe abdominal pain and may persist for several weeks. children infected with rotavirus usually make a full recovery within three to eight days. however, in poor countries treatment for severe infections is often out of reach and persistent diarrhea is common. dehydration is a common complication of diarrhea. severe dehydration in children may be recognized if the skin color and position returns slowly when pressed. this is called "prolonged capillary refill" and "poor skin turgor". abnormal breathing is another sign of severe dehydration. repeat infections are typically seen in areas with poor sanitation, and malnutrition. stunted growth and long-term cognitive delays can result. reactive arthritis occurs in 1% of people following infections with campylobacter species. guillain–barré syndrome occurs in 0.1%. hemolytic uremic syndrome (hus) may occur due to infection with shiga toxin-producing escherichia coli or shigella species. hus causes low platelet counts, poor kidney function, and low red blood cell count (due to their breakdown). children are more predisposed to getting hus than adults. some viral infections may produce benign infantile seizures. cause viruses (particularly rotavirus (in children) and norovirus (in adults)) and the bacteria escherichia coli and campylobacter species are the primary causes of gastroenteritis. there are, however, many other infectious agents that can cause this syndrome including parasites and fungus. non-infectious causes are seen on occasion, but they are less likely than a viral or bacterial cause. risk of infection is higher in children due to their lack of immunity. children are also at higher risk because they are less likely to practice good hygiene habits. children living in areas without easy access to water and soap are especially vulnerable. viral rotaviruses, noroviruses, adenoviruses, and astroviruses are known to cause viral gastroenteritis. rotavirus is the most common cause of gastroenteritis in children, and produces similar rates in both the developed and developing world. viruses cause about 70% of episodes of infectious diarrhea in the pediatric age group. rotavirus is a less common cause in adults due to acquired immunity. norovirus is the cause in about 18% of all cases. generally speaking, viral gastroenteritis accounts for 21–40% of the cases of infectious diarrhea in developed countries. norovirus is the leading cause of gastroenteritis among adults in america accounting for about 90% of viral gastroenteritis outbreaks. these localized epidemics typically occur when groups of people spend time proximate to each other, such as on cruise ships, in hospitals, or in restaurants. people may remain infectious even after their diarrhea has ended. norovirus is the cause of about 10% of cases in children. bacterial salmonella enterica serovar typhimurium (atcc 14028) as seen with a microscope at 1000 fold magnification and following gram staining in some countries, campylobacter jejuni is the primary cause of bacterial gastroenteritis, with half of these cases associated with exposure to poultry. in children, bacteria are the cause in about 15% of cases, with the most common types being escherichia coli, salmonella, shigella, and campylobacter species. if food becomes contaminated with bacteria and remains at room temperature for a period of several hours, the bacteria multiply and increase the risk of infection in those who consume the food. some foods commonly associated with illness include raw or undercooked meat, poultry, seafood, and eggs; raw sprouts; unpasteurized milk and soft cheeses; and fruit and vegetable juices. in the developing world, especially sub-saharan africa and asia, cholera is a common cause of gastroenteritis. this infection is usually transmitted by contaminated water or food. toxigenic clostridium difficile is an important cause of diarrhea that occurs more often in the elderly. infants can carry these bacteria without developing symptoms. it is a common cause of diarrhea in those who are hospitalized and is frequently associated with antibiotic use. staphylococcus aureus infectious diarrhea may also occur in those who have used antibiotics. acute "traveler's diarrhea" is usually a type of bacterial gastroenteritis, while the persistent form is usually parasitic. acid-suppressing medication appears to increase the risk of significant infection after exposure to a number of organisms, including clostridium difficile, salmonella, and campylobacter species. the risk is greater in those taking proton pump inhibitors than with h2 antagonists. parasitic a number of parasites can cause gastroenteritis. giardia lamblia is most common, but entamoeba histolytica, cryptosporidium spp., and other species have also been implicated. as a group, these agents comprise about 10% of cases in children. giardia occurs more commonly in the developing world, but this type of illness can occur nearly everywhere. it occurs more commonly in persons who have traveled to areas with high prevalence, children who attend day care, men who have sex with men, and following disasters. transmission transmission may occur from drinking contaminated water or when people share personal objects. water quality typically worsens during the rainy season and outbreaks are more common at this time. in areas with four seasons, infections are more common in the winter. worldwide, bottle-feeding of babies with improperly sanitized bottles is a significant cause. transmission rates are also related to poor hygiene, (especially among children), in crowded households, and in those with poor nutritional status. adults who have developed immunities might still carry certain organisms without exhibiting symptoms. thus, adults can become natural reservoirs of certain diseases. while some agents (such as shigella) only occur in primates, others (such as giardia) may occur in a wide variety of animals. non-infectious there are a number of non-infectious causes of inflammation of the gastrointestinal tract. some of the more common include medications (like nsaids), certain foods such as lactose (in those who are intolerant), and gluten (in those with celiac disease). crohn's disease is also a non-infectious cause of (often severe) gastroenteritis. disease secondary to toxins may also occur. some food-related conditions associated with nausea, vomiting, and diarrhea include: ciguatera poisoning due to consumption of contaminated predatory fish, scombroid associated with the consumption of certain types of spoiled fish, tetrodotoxin poisoning from the consumption of puffer fish among others, and botulism typically due to improperly preserved food. in the united states, rates of emergency department use for noninfectious gastroenteritis dropped 30% from 2006 until 2011. of the twenty most common conditions seen in the emergency department, rates of noninfectious gastroenteritis had the largest decrease in visits in that time period. pathophysiology gastroenteritis is defined as vomiting or diarrhea due to inflammation of the small or large bowel, often due to infection. the changes in the small bowel are typically noninflammatory, while the ones in the large bowel are inflammatory. the number of pathogens required to cause an infection varies from as few as one (for cryptosporidium) to as many as 108 (for vibrio cholerae). diagnosis gastroenteritis is typically diagnosed clinically, based on a person's signs and symptoms. determining the exact cause is usually not needed as it does not alter the management of the condition. however, stool cultures should be performed in those with blood in the stool, those who might have been exposed to food poisoning, and those who have recently traveled to the developing world. it may also be appropriate in children younger than 5, old people, and those with poor immune function. diagnostic testing may also be done for surveillance. as hypoglycemia occurs in approximately 10% of infants and young children, measuring serum glucose in this population is recommended. electrolytes and kidney function should also be checked when there is a concern about severe dehydration. dehydration a determination of whether or not the person has dehydration is an important part of the assessment, with dehydration typically divided into mild (3–5%), moderate (6–9%), and severe (≥10%) cases. in children, the most accurate signs of moderate or severe dehydration are a prolonged capillary refill, poor skin turgor, and abnormal breathing. other useful findings (when used in combination) include sunken eyes, decreased activity, a lack of tears, and a dry mouth. a normal urinary output and oral fluid intake is reassuring. laboratory testing is of little clinical benefit in determining the degree of dehydration. thus the use of urine testing or ultrasounds is generally not needed. differential diagnosis other potential causes of signs and symptoms that mimic those seen in gastroenteritis that need to be ruled out include appendicitis, volvulus, inflammatory bowel disease, urinary tract infections, and diabetes mellitus. pancreatic insufficiency, short bowel syndrome, whipple's disease, coeliac disease, and laxative abuse should also be considered. the differential diagnosis can be complicated somewhat if the person exhibits only vomiting or diarrhea (rather than both). appendicitis may present with vomiting, abdominal pain, and a small amount of diarrhea in up to 33% of cases. this is in contrast to the large amount of diarrhea that is typical of gastroenteritis. infections of the lungs or urinary tract in children may also cause vomiting or diarrhea. classical diabetic ketoacidosis (dka) presents with abdominal pain, nausea, and vomiting, but without diarrhea. one study found that 17% of children with dka were initially diagnosed as having gastroenteritis. prevention percentage of rotavirus tests with positive results, by surveillance week, united states, july 2000 – june 2009 water, sanitation, hygiene further information: wash § health aspects a supply of easily accessible uncontaminated water and good sanitation practices are important for reducing rates of infection and clinically significant gastroenteritis. personal hygiene measures (such as hand washing with soap) have been found to decrease rates of gastroenteritis in both the developing and developed