What is gastroenteritis?

Alternative names: Gastro, gastric flu, diarrhoeal disease, traveller’s diarrhoea, food poisoning

Gastroenteritis is an inflammation of the lining of the stomach as well as the small and large intestines, which leads to an acute infectious syndrome. It’s usually caused by microorganisms that have been ingested via contaminated food or water, but gastroenteritis can also be caused by ingested chemical toxins or drugs.

Microorganisms such as viruses, bacteria and parasites cause gastroenteritis by secreting toxins that stimulate excessive water and electrolyte loss, thereby causing diarrhoea. The microorganisms can also directly invade the walls of the gut. This starts an inflammatory process that upsets the balance between the absorption of nutrients and the secretion of wastes.

Gastroenteritis isn’t usually serious in healthy adults; in most instances, it causes only discomfort and inconvenience. However, it can cause life-threatening dehydration and electrolyte imbalances in very ill and weak individuals as well as in very young or old individuals.

Reviewed by Kim Hofmann, registered dietitian, BSc Medical (Honours) Nutrition and Dietetics, BSc (Honours) Psychology. December 2017.