Norovirus is a contagious virus, causing vomiting and diarrhea.
The virus is often called the stomach flu, although it is not related to influenza.
It's so contagious that if one person has it in an enclosed space, more than 90% of those exposed will also become infected.
Transmission can occur through contact with vomit or feces, contaminated food or water, or by touching contaminated surfaces.
Infected people are most contagious during the first three days of illness.
The most common symptom is projectile vomiting.
Other symptoms include watery diarrhea, nausea, abdominal pain, and low-grade fever.
Doctors cannot prescribe specific medications to help people get better if they're suffering from norovirus.
Antibiotics do not help because they only kill bacteria, and norovirus is a virus.
To help prevent dehydration, drink plenty of fluids, especially clear liquids.