Objective: This is the third survey we perform in the kibbutz population of Israel. The previous 2 surveys were 10 years apart, in 1987 and 1997, demonstrating an increase in ulcerative colitis (UC) prevalence. The aim of the present study was to confirm the trend for increasing UC prevalence in Israel.

Methods: There are 269 kibbutz settlements in Israel, with a total of 117,700 people, accounting for 2.4% of the Jewish Israeli population. The local physician for each kibbutz was contacted by mail, e-mail, telephone, and fax to obtain information on UC patients. Data were retrieved and updated to December 31, 2007, the point prevalence date. Details of sex, age, origin, clinical spectrum of the disease, therapy, and complications were recorded.

Results: There are 255 confirmed cases of UC, 138 women and 117 men (female: male ratio, 1.2:1). The prevalence rate rose from 121.08/100,000 in 1987 to 167.20/100,000 in 1997 and then to 216.65/100,000 in 2007 (P<0.0001). The rise in the second period was less than in the first period: 29% and 38%, respectively. The prevalence rate was higher in women than men, and in European/American-born>Asian/African-born>Israeli-born individuals.

Conclusions: We observed an increase in the prevalence and mean annual incidence of UC in Israel, in men and women, with a decreasing gap between different ethnic groups. We believe that strong environmental influence is responsible for our observation.