Gastroenteritis is inflammation of the gastrointestinal tract, particularly the stomach and intestines, typically producing diarrhoea, vomiting, abdominal cramps and sometimes fever. It is most commonly infectious, with viruses, bacteria and parasites among the possible causes, although the term can sometimes be used more broadly for inflammatory gastrointestinal illness. Acute infectious Gastroenteritis is one of the most common causes of diarrhoea and vomiting worldwide. The clinical course ranges from a brief, self-limiting illness to severe disease causing dehydration, invasive infection or complications in vulnerable people.
Viral Gastroenteritis is a major cause of acute gastrointestinal illness. Viruses such as norovirus and rotavirus can spread efficiently through contaminated hands, food, water and environmental surfaces. Bacterial Gastroenteritis can result from organisms that invade intestinal tissue or produce toxins, while parasitic disease can cause prolonged diarrhoea and malabsorption. The incubation period, duration, severity and associated symptoms vary among pathogens. Some organisms cause predominantly vomiting, while others produce inflammatory diarrhoea, fever or blood in the stool. The specific pathogen often cannot be identified without laboratory testing, and testing is not necessary for every uncomplicated episode.
Transmission of Gastroenteritis depends on the causative organism. Faecal-oral transmission is particularly important, meaning that microscopic contamination from infected stool can reach another person's mouth through hands, surfaces, food or water. Some pathogens have very low infectious doses and can survive on environmental surfaces, facilitating outbreaks in households, schools, healthcare facilities and other crowded settings. Food handlers can transmit infection even without severe symptoms. Appropriate handwashing, environmental cleaning, safe food preparation and exclusion from certain activities while infectious can reduce transmission.
The main clinical concern in acute Gastroenteritis is fluid and electrolyte loss through diarrhoea and vomiting. Symptoms can include abdominal cramps, nausea, fever, malaise and reduced appetite. Most uncomplicated cases improve as the infection resolves, but dehydration can become dangerous, particularly in young children, older adults and people with significant underlying illness. Blood in stool, persistent high fever, severe abdominal pain, prolonged symptoms or neurological deterioration can indicate more invasive or complicated disease. Clinical assessment should therefore consider both the likely pathogen and the physiological consequences of fluid loss.
Treatment of uncomplicated Gastroenteritis is usually supportive. Oral rehydration solutions replace water and electrolytes and are particularly important when diarrhoea is substantial. Continued appropriate nutrition can support recovery, and breastfeeding should generally continue during infant diarrhoeal illness. Antibiotics are not routinely useful because many cases are viral and some bacterial infections resolve without antimicrobial treatment; unnecessary antibiotics can cause adverse effects and contribute to resistance. Antimotility medicines may be unsuitable in some circumstances, particularly when there is bloody diarrhoea or suspected invasive infection, so treatment should reflect the clinical presentation.
Diagnosis of Gastroenteritis is often clinical when symptoms are acute, uncomplicated and typical. Stool testing can be appropriate during outbreaks, in severe disease, in immunocompromised patients, when there is blood in the stool, after certain travel exposures or when symptoms persist. Testing may identify bacterial, viral or parasitic pathogens and can assist public-health investigations. Blood tests may be needed when dehydration, systemic infection or electrolyte disturbances are suspected. Imaging is generally reserved for situations in which another diagnosis, such as appendicitis or obstruction, needs to be considered.
Prevention of Gastroenteritis relies heavily on hygiene and public-health infrastructure. Safe drinking water, sanitation, hand hygiene, appropriate food storage and cooking, and effective cleaning of contaminated surfaces are fundamental. Vaccination against rotavirus substantially reduces severe rotavirus gastroenteritis in infants where vaccination is included in national programmes. During outbreaks, rapid identification of cases and appropriate infection-control measures can limit transmission. Food-safety systems also monitor and control pathogens that can contaminate meat, eggs, dairy products, seafood, produce and prepared foods.
Gastroenteritis should be distinguished from food poisoning, although foodborne infections are an important cause of gastroenteritis and the terms can overlap in everyday usage. Gastroenteritis describes the clinical syndrome of gastrointestinal inflammation and associated symptoms, whereas food poisoning generally emphasises illness caused by consuming contaminated food or drink. Gastroenteritis can also arise through person-to-person transmission or contaminated water without a food exposure. Similarly, inflammatory bowel disease can cause diarrhoea and abdominal pain but is not an acute infectious gastroenteritis. Accurate terminology therefore depends on whether the focus is the clinical syndrome, the infectious cause or the route of exposure.
