Hand, foot, and mouth disease is a highly contagious infection that is common in children but can also affect adults. It's caused by viruses from the enterovirus genus - viruses that cause infectious but usually mild illnesses. The most common of these is the coxsackievirus. It spreads via coughs, sneezes, poo and the fluid inside blisters.
This is a companion discussion topic for the original article at https://patient.info/news-and-features/what-is-the-difference-between-hand-foot-and-mouth-disease-and-chickenpox