Noroviruses are a group of viruses that cause the "stomach flu," or gastroenteritis (GAS-tro-enter-I-tis), in people. The term norovirus was recently approved as the official name for this group of viruses. Several other names have been used for noroviruses, including:
- Caliciviruses (because they belong to the virus family Caliciviridae)
- Norwalk-like viruses (NLVs)
- Small round structured viruses
Viruses are very different from bacteria and parasites, some of which can cause illnesses similar to norovirus infection. Viruses are much smaller, are not affected by treatment with antibiotics, and cannot grow outside of a person's body.