Ulcerative colitis is one of the two major inflammatory bowel diseases. It affects around one in every 500 people in the United Kingdom.
Unlike Crohn’s disease that affects women slightly more frequently than men, Ulcerative colitis seems to affect both sexes equally or may affect men slightly greater than women.
Ulcerative colitis may start at any age. However, it is rare in children under the age of 5. In most cases the symptoms begin to appear when the person is between ages of 10 and 40 years.
Ulcerative colitis is most common in white people of European descent, especially those descended from Ashkenazi Jews. It is seen more commonly among people who have lived for generations in Eastern Europe and Russia. The condition is also common in black individuals but is rarer among those of Asian descent.
The reason for higher prevalence in urban areas and in northern developed countries in Western Europe and America compared to rural areas is unknown. However it has been seen that the prevalence and incidence of new cases is on the rise in developing nations as well.
There are no incidence figures available for either ulcerative colitis or Crohn’s disease until the 1930s. Between 1934 and 1944 the incidence rates of Ulcerative colitis were first reported in two studies done retrospectively in Rochester, Minnesota. The studies found that annually there were 6 cases of Ulcerative colitis per 100 000 population. After this the numbers have been on a steady rise both in Europe and in the Americas.
There has been a lack of gold standard criteria for diagnosis, inconsistent assessment of cases and misclassification of the diseases that has made epidemiological studies of these diseases in large populations difficult.
According to the Centers of Disease Control and Prevention (CDC) the worldwide incidence or diagnosis of new cases of Ulcerative colitis varies considerably between 0.5 and 24.5 per 100.000 populations. Overall prevalence of inflammatory bowel disease worldwide is 396 per 100,000 persons. Nearly 1.4 million persons in the United States suffer from these diseases.