Seriously, wash your god damn hands. Especially after going to the bathroom. Over the last few years I have shouted at people from stalls to wash their hands.
Just on a local basis there have been too many news stories over my life time of people getting infections from food prepares not properly washing hands after using the head. In a given day I may wash my hands a dozen or more times based on what I am doing just to avoid passing germs to someone else.
In the event anyone is confused on how to properly wash ones hands I will include a link to how the CDC recommends washing hands.