Q: How does calcivirus cause diarrhoea?

A:Caliciviruses (a family of single-stranded RNA viruses) are an important viral cause of diarrhoea along with other viruses like rotavirus, the enteric adenoviruses and astrovirus. The name calicivirus is derived from the Latin word calyx meaning cup or goblet, as many strains of the virus have visible cup-shaped depressions. Within the calicivirus family, noroviruses and sapoviruses cause gastrointestinal disease in humans. These viruses are very widely distributed worldwide & infection is very common, especially in children. A seasonal peak occurs during the cooler months, coinciding with the rotavirus peak in temperate climates. They are a common cause of gastroenteritis outbreaks in developed countries, as well as sporadic cases of acute gastroenteritis with vomiting, abdominal cramps, diarrhoea, headache and fever. The noroviruses tend to occur in older children and adults in common-source outbreaks where food is contaminated e.g. cold foods like salad at a restaurant, or through swimming in or drinking sewage contaminated water, or eating shellfish harvested from sewage polluted water. The illness is an explosive but short-lived episode. Most patients make a full recovery within a couple of days and do not require medical attention.