Norovirus is a very contagious virus. You can get norovirus from an infected person, contaminated food or water, or by touching contaminated surfaces. The virus causes your stomach or intestines or both to get inflamed. This will give you stomach pain, nausea, vomiting, and diarrhea. Anyone can be infected with norovirus and get sick. You can have norovirus illness many times in your life. Norovirus illness can be serious, especially for young children and older adults. The best way to help prevent norovirus is to practice proper hand washing and general cleanliness.