There are three kinds of food poisoning that can easily spread between people if food is not prepared correctly. They are salmonella, E. Coli, and the norovirus. This is actually most commonly done after going to the bathroom, and unintentionally. Food poisoning often means you’re in the bathroom a lot - either throwing up or on the toilet with diarrhea, or possibly both. Whatever is coming up or out in the bathroom will be contaminated with the food poisoning bacteria that is making you sick. If you don’t wash your hands properly and disinfect thoroughly, you could unintentionally make someone else sick.
The best way to prevent this is to make sure you’re being extremely cautious when you are sick with food poisoning. Disinfect the bathroom thoroughly with a deep clean or with Lysol wipes.