Rotaviruses are a leading cause of severe diarrhoeal disease and dehydration in infants and young children throughout the world. Most symptomatic episodes occur in young children between the ages of 3 months and 2 years. The virus spreads rapidly, presumably through person-to-person contact, airborne droplets, or possibly contact with contaminated toys. Symptoms usually appear approximately two to three days after infection, and include projectile vomiting and very watery diarrhoea, often with fever and abdominal pain. The first infection is usually the worst one. There is no specific drug treatment for rotavirus infection, although oral rehydration therapy is recommended. There are now two new rotavirus vaccines to prevent severe rotavirus disease.