What is Crohn’s disease?
Crohn’s disease is a chronic condition. This means that it is ongoing and life-long, with alternating periods of good health (remission) and times when symptoms are more active (relapses or flare-ups).
Inflammation of the gastrointestinal tract
Crohn’s disease can affect any part of the digestive system, from the mouth to the anus. The areas of inflammation are often patchy with sections of normal gut in between.
In its early stages, Crohn's disease may be manifested as red lesions and white aphthous ulcers with a red rim on the inner surface of the bowel. With time, the aphthous ulcers become deeper and longer (true ulcers). In later stages, the thickening of the intestinal wall develops and can cause narrowing of the intestinal lumen.
The inflammatory process affects all layers of the bowel wall, changes in the superficial layer of the bowel mucosa reflect the activity in the deeper layers of the intestinal wall. In some cases, inflammation and ulcers can extend completely through the intestinal wall, creating an abscess or fistula, an abnormal passage or tunnel from one part of the intestine to another or to nearby organs (skin, bladder, ...).
Crohn’s disease runs its course in flares. A disease-free period (remission) is followed by periods in which the disease flares up and symptoms become active due to inflammation. It is not possible to determine the onset of these periods, and there is also no way to predict whether the inflammation will spread and whether even more intensive manifestations will appear.
As we can see, Crohn’s disease does not present with persisting problems and is a very ‘individual’ condition. Every patient is affected in a different way. Some people have a mild course of the disease with few complications and medical treatment is required only in the most active phase of the disease. Others experience disease progression characterized by strictures, abscesses and fistulas, requiring immune-modulating therapy and/or surgery.
Extraintestinal manifestations of Crohn’s disease.
Baumgart et al., 2012
Causes of the disease
Crohn’s disease is a chronic condition. This means that it is ongoing and life-long, with alternating periods of good health (remission) and times when symptoms are more active (relapses or flare-ups). The exact cause of Crohn’s disease is not known. Researchers believe that Crohn's disease may be a result of multiple factors, including genetics, abnormal reaction of the immune system and environmental factors.
Epidemiology of the disease
Both men and women are equally likely to develop Crohn's disease. It mostly affects young adults and adolescents between the ages of 15 and 35; however, it can occur in younger children and adults as well. Every fifth patient with Crohn’s disease is younger than 20 years of age. The disease can be also diagnosed in babies.
A lot of different data on the incidence and prevalence of Crohn’s disease have been published. There are significant differences in data on the geographical location of the survey. The differences can be partially explained by the environmental impacts, such as the varying degree of urbanization and eating habits. Differences are also the result of differences in genetic and other environmental factors between individual ethnic groups. In Europe prevalence of Crohn’s disease vary from 0.6 / 100.000 inhabitants (Greece) to 322 / 100.000 inhabitants (Germany).
- Tsianos, E., et al., The epidemiological profile of inflammatory bowel disease in different parts of North-West Greece. Ann Gastroenterol, 2005. 18: p. 434-440.
- Hein, R., et al., Prevalence of inflammatory bowel disease: estimates for 2010 and trends in Germany from a large insurance-based regional cohort. Scandinavian journal of gastroenterology, 2014. 49(11): p. 1325-1335.
- Baumgart, Daniel C., Sandborn, William J. Crohn's disease. The Lancet, 2012, 380 (9853):1590-1605.