They've both answered perfectly, I just feel like adding that a friend of my mother's had a girlfriend who had that and she had to go to the hospital a lot because she was more prone to infections and one ti e he got mad at her for what ever reason and kicked her in the stomach and she soiled herself and had to go to the hospital. :)
It's an inflammatory disease of the intestines. It's not normally fatal, but complications from it could be fatal if not taken care of.
