I can't think of any high risk foods I've eaten, but at work I do often buy a toasted sandwich with avocado, tomato and cheese (safe to eat, cheddar cheese), do you think I could get listeria from the tomato? I know unwashed unvegetables can cause it but I thought that was more in the case of lettuce and leafy vegetables. Any thoughts? Can't help but be worried...
It's more a concern if the ingredients have been cross contaminated. One example could be someone constructing the sandwich touches ham and then goes to get a piece of tomato/cheese/avocado and accidentally brushes another piece not going on the current sandwich. The toasting process should remove any bacteria if it's piping hot.

Hoping all is well hun!