A rotavirus is a circular RNA virus (in Latin, rota means « wheel ») 60 to 80 µm in diameter which belongs to the Reoviridaefamily.
They are the leading cause of acute diarrhoea in young children throughout the world. Whilst they cause gastro-enteritis in children they are asymptomatic in adults. Some sources estimate that they are responsible for 500,000 deaths in children under 5 years old each year throughout the world, the very great majority in poor African and Asian countries.
Their name rotavirus comes from their circular shape. They are seen here by transmission electron microscopy. The black line represents 100 nm. © FP Williams, Wikipedia, DP