Rotavirus is a non-enveloped, double-shelled virus that is named because of its wheel-like appearance (RNA virus, Family Reoviridae), animated coloured transmission electron micrograph (TEM). Human rotaviruses cause viral gastroenteritis. The primary mode of transmission is through faeces or faecal contaminated water. It is the most common cause of severe diarrhoea among young children world wide. Typically rotavirus infects the intestines in children of age 6 months to 3 years. The diarrhoea results in fluid loss and severe dehydration. Original image courtesy of the CDC.