There is a pretty vicious GI bug running around our area. I am generally not susceptible to these things, but even I got it and it was horrific. Well, a few days afte it hit our house, DH stopped for coffee at the quick market by his work. This little gas station, deli, market sells sandwiches, pastry etc. The cashier looked like death. Turns out she has the bug, but chose to go to work. I know! I know!! She needs the money! But think about it. She handles food and has this nasty germ catapulting around her, handles your food and makes your coffee.
People on vacation sometimes have this mindset. They paid good money for a vacation, and they do not want to miss it. You follow them all over the parks, into restrooms, onto attractions and into the restaurants. As much as we all want to believe that GI thing that we caught was food poisoning, it generally is a virus that someone else gifted us with.