Rotavirus is transmitted orally, meaning that someone touches something that has the virus on it and then touches their mouth or eats some food. This is very common in day cares where the staff has to change many diapers a day. Unfortunately, rotavirus is very hardy and is not usually killed by normal hand-washing routines. This makes it very easily spread, and almost all children will have at least one infection before the age of five. The virus is most common in the winter and early spring, between November and May.