I know first hand what can happen. On Legend way back in the day, Diamond lounge had used the same platter for shrimp as other canape's and a lady got really sick had to go to the clinic and the Chef and a bunch of people came up to the lounge whilst we were there to inspect everything. A really big deal. She was allergic to shell fish. She ate some of the other pieces not knowing shrimp had been on the platter, somehow that was enough.