Noroviruses (formerly known as Norwalk-like viruses) can
cause large outbreaks of gastrointestinal disease in
humans. Infection with norovirus is commonly
characterised by a sudden onset of diarrhoea and/or
vomiting, lethargy, headache, abdominal discomfort,
nausea, anorexia, and fever. Symptoms start about 12–36
hours after a person acquires the infection and usually
resolve within 72 hours. Most people recover with rest;
however, symptoms can sometimes be severe and require
treatment in hospital. Illness often results in working days
lost and other costs.