Gastrointestinal viruses like norovirus can cause nausea, diarrhea, and vomiting in infected people; sometimes it may also result in a fever and aches. While the illness usually resolves on its own, people have to endure severe discomfort before it's over.
You have probably heard of norovirus because it can cause serious outbreaks on cruise ships. The virus spreads quite easily, and that is only exacerbated when a large number of people are staying in close quarters.
Preventing this illness is as simple as practicing good hand hygiene, however. Washing your hands properly, especially before you eat, can keep you from getting sick. It also helps not to touch your face often unless your hands are clean. Learn more from the Mayo Clinic video.