Like most viruses, rotaviruses are made from RNA and protein. The RNA carries the genes that are used to make more rotaviruses. They are called rotaviruses because they sometimes look like little wheels and "rota" is the latin word for "wheel". Rotaviruses get into the body through the mouth and are not present in the air like the viruses that cause colds. The disease is most often spread by dirty hands and things used for cooking, but the viruses can contaminate water. Rotaviruses are very small. They are a lot smaller than bacteria and can only be seen using an electron microscope. 