What causes Appendicitis?

I've never heard that activity after a full meal will cause an appendicitis attack. I think it is caused because the appendix becomes irritated in some way. Usually this is due to the appendix becoming blocked from a back-up from the digestive track which causes a bacterial infection. The appendix becomes infected and must be removed. However, it has nothing to do with activity before, during of after a meal. It may begin as a stomach virus or other type of virus that causes this to happen, but not very often though.