Group A rotaviruses are distributed worldwide, and are the commonest cause of infantile gastroenteritis. In developing countries, the burden of rotavirus disease in children under 5 years of age has been estimated to be >114 million cases annually, of which over 20 million are severe cases, and 500,000 – 800,000 deaths are attributable to rotavirus diarrhoea. One in 205 children will die as a result of rotavirus infection. In the developed world, mortality due to rotavirus infection is very low, however, it is an important cause of morbidity and of hospitalisation in young children. Rotavirus disease occurs typically in winter peaks in temperate climate zones of the world; by contrast, in tropical countries, rotavirus infection and disease occur all year round.
Rotaviruses have a triple layered capsid and a wheel-like structure, and their genome consists of 11 segments of double stranded RNA. Rotaviruses are classified into groups A-E, and most human rotavirus infections are associated with group A rotaviruses. Group B rotaviruses are common animal pathogens infecting pigs, cows, sheep and rats, but have also been found infecting humans. Group C rotaviruses, commonly found in animals including pigs and dogs, can cause outbreaks in the human population.