A few years ago, we got Chinese take out and my husband and I were the only ones to eat a particular dish, and coinkydink, we were the only ones who got sick to our stomachs about 8 hours later. I tend to think all along, I was making my family sick with bacteria from meat...
I have also noticed that sometimes my children who attend one school will get "the stomach flu" but not the two who attend the other school and vice versa. If it were a virus, it should spread at home. I'm thinking that they were served the same "bad" food.
Just my theory.