For some reason, almost every year we go to Disney, someone in my party is sick when we go or gets sick when we are there. For this reason, I try to make sure I pack various pain relievers/cold remedies (we go in the winter - sickness is usually respiratory). I also go out of my way to make sure to pack and use hand sanitizers for my whole party to reduce our risks.

One other thing comes to mind. When my son was almost 2 (my other son was 6), we got caught in the worst storm ever at Animal Kingdom. I would definitely recommend taking a stroller cover for an event such as this if you are going at a time when you think storms like this may happen (we went in November). It was an all day rain/storm and we were all soaked to the skin as well as our stroller - I think we ended up having to rent a stroller for at least the next day b/c the stroller was that wet.