Colitis is a description, not a diagnosis, and its causes vary widely
Colitis simply means an inflamed colon. Doctors use the bare word when they do not yet know the cause, or when everyone in the room already does. Behind it sit very different illnesses: bacterial infections, parasites, lifelong inflammatory bowel disease and a type visible only under a microscope.
The large intestine can become inflamed briefly and recover on its own, or stay inflamed for years. Symptoms depend on the cause and severity, but commonly include belly pain and tenderness, persistent bloody diarrhoea sometimes containing pus, incontinence, wind, tiredness, poor appetite and unexplained weight loss. Serious cases can bring fever, breathlessness and a racing or irregular heartbeat, and some patients also develop joint pain, mouth ulcers, inflamed skin or red, irritated eyes.
Working out what is going on starts with history, examination and laboratory tests such as blood counts, electrolytes and stool cultures checked for bacteria and parasites. Scans or X-rays may follow, along with a camera examination of the bowel, which can show reddened lining, ulcers and bleeding. A key step is a biopsy: a fragment of lining about 2 mm across is examined by a pathologist. The report usually stops short of naming a disease but notes whether inflammation looks chronic, how active it is and whether the surface is eroded or ulcerated.
Colitis is classified by cause. Ulcerative colitis and Crohn's disease belong to the chronic group known as inflammatory bowel disease; when features of both appear, doctors call it indeterminate colitis, which usually behaves more like the ulcerative form. Microscopic colitis looks normal to the naked eye and is revealed only in tissue samples. Infection is another route. Clostridioides difficile, nicknamed C-diff, can leave telltale pseudomembranes, the Shiga toxin made by Shigella dysenteriae and certain E. coli strains such as O157:H7 causes a bloody form, and the parasite Entamoeba histolytica can also inflame the colon.
Treatment depends on the type and can include steroid medicines and changes in diet, with hospital care or surgery in some cases. Several recent studies have reported a significant link between colitis and allergy to dairy proteins such as casein.
Source: Colitis
