Israel is a pretty modern country and health services are very good. You can eat the food and drink the water without much risk of disease. I didn't get any vaccines before going over there on excavation.You should probably talk to doctor about it if you're concerned.
There are heaps of Americans over there, it's not an issue if you're sticking to the big cities. Obviously you use a bit of common sense and keep your wits about you though. Don't go to Gaza or the West Bank.