It could be that the measles vaccine may be one vastly under-reported cause of Crohn's. But retrospective analyses are hard to perform accurately (Lancet, 1996; 347: 263), and it would be difficult to find a large enough group of children today who have not been vaccinated whom researchers could use as controls in a large prospective trial (Lancet, 1995; 345: 1363-4; J Gastroenterol, 1995; 344: 48-51; Gut, 1996; 38: 211-5).

While the true cause remains unproven, there is similar uncertainty about treatment.

Surgery is a mainstay of the conventional approach and it can help but at a price. Surgeons may take out as much as 50 per cent of the small intestine, but it should be viewed as a relief of symptoms rather than a cure (Int Surg, 1992; 10: 2-8). It can also cause malabsorption, diarrhea and other nutritional disturbances. In a study of 62 patients with Crohn's aged 55 years or over surgery helped restore good health, but nearly half of the patients required a permanent stoma (surgically-created opening in the abdomen) (Postgrad Med J, 1997; 73: 225-9).

In another group of 212 patients, surgery resulted in high death rates (28.3 per cent); and 60 patients had at least one complication, mainly of a septic nature. The mortality rate was 3.3 per cent, with infection, deep vein thrombosis and pulmonary embolism being the most common cause of death. Those who were nutritionally compromised because of the disease had a significantly higher rate of complications (39.7 per cent), as did those who required emergency surgery (44.4 per cent). This suggests that taking the time to improve health before surgery will result in significantly better results (Neth J Surg, 1990; 42: 105-9).

While the initial result of surgery is good, as many as 38 per cent of patients will be re-operated on within 10 years and 54 per cent within 15 years (Tidsskr Nor Laeegeforen, 1994; 114: 1603-5).

Steroids are the primary treatment for Crohn's (Gastroenterol, 1984; 86: 249-66). But steroids such as cyclosporin can cause kidney damage even at low initial doses which cannot be reversed by later dose reduction (Dig Dis Sci, 1993; 38: 1624-30) Also, steroid dependency occurs in more than a third of users and steroid resistance in 20 per cent taking the drugs for the first time (Gut, 1994; 35: 360-2; Lancet, 1995; 345: 859).

Steroid use is, of course, associated with development of the bone disease osteoporosis. This is particularly true in patients with both Crohn's and ulcerative colitis since the disease often results in a secondary malabsorption of calcium and vitamin D. In one study, patients with Crohn's had diminished bone density of the hip by 64 per cent and of the spine by 44 per cent. In UC patients, hip density was diminished by steroid use by 43 per cent and density of the spine by 48 per cent (J Bone Miner Res, 1995; 10: 250-6). Steroid use was the only significant predicting factor for reduced bone density.

Anti-diarrheal and antispasmodic preparations and sedatives are often prescribed for symptom relief. Bowel inflammation is often controlled with sulphasalazine or the newer 5 amino salicylic acid (5-ASA) compounds, anti-bacterial drugs and adrenocortical steroids and the immunosuppressive compounds 6-mercaptopurine (6-MP), azathioprine and cyclosporin.

Immunosuppressives such as 6-MP and azathioprine are often used to wean patients from steroids. They are used mainly as maintenance therapy and to close fistulas (where two normally unconnected tissues join up), though the action can take some time to show its effect. These drugs are associated with side effects such as liver damage or bone marrow suppression, and their action is still not well understood. One study has shown that after four years of remission on these drugs, the risk of relapse appeared to be similar, whether the therapy was maintained or stopped (Lancet, 1996; 347: 215-19).