Having had HFMD can also be contagious because there are more than 20 types of enteroviruses that cause HFMD. These enteroviruses are stable in a liquid environment, and the virus can survive for a long time in an external environment. The common HFMD viruses are Coxsackie A group 16 virus, and enteric EV71 virus. The EV71 virus is a new type of virus discovered after 2008, known as enterovirus 71, or EV71 for short, which is now causing an increasing proportion of HFMD cases and is much more virulent than Coxsackie A group 16, causing a large number of less serious common cases. However, it has caused some severe cases, which are very serious and have led to death in some cases. The usual infection of HFMD virus is according to the typology, in addition to these two main typologies, may also be other typologies, that is, the previous infection of enterovirus, HFMD virus, if different models, this year is likely to be infected with another virus of HFMD, so have had HFMD, it is likely that HFMD infection will occur again.