Norovirus is a member of the caliciviridae family like calicivirus and sapovirus. Caliciviridae are RNA viruses with a capsid of icosahedral symmetry. They are not wrapped, which gives them better resistance to detergents and biocides. Its virion is around 35 nm in size and its genome, like that of picornaviruses, is 8,000 base pairs.
Noroviruses are particularly infectious and 10 to 100 particles are capable of infecting 50% of those exposed. Those affected will experience nausea with projectile vomiting. Note that this virus is very resistant and that hospital epidemics are sometimes documented. Norovirus is also prevalent over the holiday season and sometimes occurs in an epidemic context during ski camps.
There is a rapid PCR test that allows precise diagnosis, which helps in setting up measurements.