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.
In most cases, the prognosis of gastroenteritis is good and symptoms generally begin to resolve within about 2 to 5 days. Although the infections are usually acute (i.e. short illness), some parasites (e.g. Giardia) can lead to chronic (long-lasting) disease. If your symptoms don’t improve within two weeks, you should visit your doctor.
The prognosis for prolonged gastroenteritis (lasting more than 2 weeks) depends on the correct identification and treatment of the underlying cause. The prognosis can be good (in the case of food intolerances or allergies and medication side effects) to fair to poor (in the case of heavy metal toxicity and cytomegalovirus infection in HIV-compromised individuals).
Watch out for dehydration, especially in infants and young children. Extreme loss of body fluid and electrolytes can lead to shock, coma or even death.
Symptoms of serious dehydration include:
• Dry mucous membranes in the mouth.
• Loss of the normal elasticity of the skin.
• In babies, sunken eyes or sunken a fontanelle (the soft spot at the top of a baby's head).
• Fast breathing.
• A drop in urine output.
• Weight loss over days or even hours.
• Listlessness or lethargy.