Several different viruses, all spread through contact or food, can cause viral gastrointestinal infections. The two most common viruses are rotavirus and norovirus, a member of the calicivirus family. In addition to the three other types of calicivirus, other viruses that can infect the gastrointestinal tract are adenovirus and astrovirus.
All of these viruses are transmitted the same way, by direct contact or through contaminated food or water. The most common way the viruses are transmitted is when infected fecal matter comes in contact with hands and is passed on to the mouth.