Stomach illnesses peak in winter -- sometimes spread from person to person, sometimes spread via food handled by a sick person. The reason doesn’t really matter, though, when you feel horrible. And, unlike the flu, there's no vaccine you can take to prevent an infection.
Beyond campylobacter, salmonella and E. coli (all bacteriums), one of the most common culprits in food-borne illnesses is norovirus, also known as viral gastroenteritis. It's more commonly called the stomach flu -- though it's not remotely related to the flu.
This story from the Allentown Morning Call reports the toll such viruses are taking in one state: "In the first three months of this year, nursing homes in Pennsylvania reported 4,040 norovirus cases — nearly twice as many as those reported in all the nine prior months combined. The data, reported this month by the Pennsylvania Patient Safety Authority, also found hospital infections peaked in the first quarter of the year, although not as dramatically as in nursing homes."
Here are symptoms from the Centers for Disease Control and Prevention:
"Norovirus infection causes acute gastroenteritis (inflammation of the stomach and intestines); the most common symptoms are diarrhea, vomiting, and stomach pain.