Crohn's Disease is an inflammatory bowel disorder which has become increasingly common across the world since it was first identified several decades ago.
The cause of the disease is unknown, but it is suspected that viruses and bacteria could play a part.
Most people develop the disease before they are 30 and the peak age is 14-24.
What may cause it?
Most recent research has concentrated on mycobacteria. A diet low in fibre and high in chemicals is also suspected to have a role in the illness.
People with a family history of ulcerative colitis (another inflammatory bowel disorder) also run a higher risk of getting the disease.
Stress is thought to exacerbate the illness which can affect any part of the digestive system, from the mouth to the anus.
What are the symptoms?
The symptoms of Crohn's Disease can often be vague and difficult to identify.
They can involve chronic diarrhoea and abdominal pain, fever, lack of appetite, weight loss and a feeling of fullness in the gut.
Children with the disease sometimes suffer growth retardation.
People with the disease may develop bowel obstructions. abscesses and intestinal bleeding linked to rupture of the bowel.
A small proportion may go on to develop cancer of the small bowel.
Ulcer tracts in the gut which are caused by the disease can also burrow into surrounding organs, including the gall bladder, the liver and skin, causing infections.
Other possible side effects are mouth and eye inflammation, gallstones and arthritis.
What is the treatment?
Crohn's Disease can be detected using endoscopy with biopsy.
Barium x-rays can help to detect small changes in the bowel associated with the disease.
No specific treatment is used for Crohn's, but varoius drugs can be taken to relieve cramps and diarrhoea, including codeine.
Some patients, especially those with abscesses and infections, may find certain antibiotics useful.
The anti-bacterial agent Metronidazole has been shown to be effective in treating lesions in the gut, but long-term use can lead to seizures.
Other drugs which can be effective include sulfaslazine, immunosuppressive drugs and corticosteroids.
However, long-term use of corticosteroids can be toxic. Surgery can also help relieve acute bowel obstruction, but it is not a cure.
Can diet affect Crohn's?
Ironically, some people find that the symptoms of Crohn's Disease can be made worse by drinking milk as well as drinking alcohol, eating hot or fried food and eating fibre.
But this does not apply to all people with the disease.
Is there a link between Johne's Disease and Crohn's?
Johne's Disease (paratuberculosis) is a debilitating incurable intestinal disease in cattle.
It was first spotted in 1826, but was not officially recognised as an infectious disease until 1894.
Up to 18% of US cattle are thought to have the disease which mainly affects dairy herds.
This is because they are kept in closer proximity, making infection easier.
The symptoms of Johne's Disease are acute weight loss and diarrhoea. Sometimes cattle get so thin that they have to be slaughtered.
The infection hides in the intestine and lymph nodes and can survive in manure and pond water for a year or more, making transmission of the disease difficult to stop.
Symptoms of the disease are rarely seen until cattle are at least two years old.
The mycobacteria thought to be responsible for the disease are said to be present in around a half of Crohn's Disease patients.
Intestinal tuberculosis and Crohn's Disease have similarities and Crohn's patients tend to respond well to treatments for intestinal TB.
They are so similar that in some areas there is often misdiagnosis.
It was thought that pasteurising milk could cut the risk of Johne's being transferred to humans, but this is now being questioned.