Rotavirus is a genus of double-stranded RNA viruses in the family Reoviridae. It is the most common cause of diarrhoeal disease among infants and young children. The rotaviruses are in term of combinations of G and P type, refer to serotype designation and genotypic designation. There are eight species of this virus, referred to as A, B, C, D, E, F, G and H. G1P1A is the combination of P1A serotype and G genotypic designation, while the G2P1B, G3P1A and G4P1A are the most frequent phenotype in human infections. The virus is transmitted by the faecal-oral route. It infects and damages the cells that line the small intestine and causes gastroenteritis.