One of the most common presentations of enteroviral infection, usually seen in children and normally associated with the Coxsackie virus group of enteroviruses, though other serotypes have been connected with the condition.
Hand-Foot-Mouth disease (commonly abbreviated HFMD) is associated with fever; blisters and rash on hands and feet and sometimes buttocks. Often, painful ulceration in the mouth occurs, with blisters on tongue and soft palate, causing difficulty in swallowing.
HFMD is very contagious, but usually strikes children (presumably due to poorer standards of personal hygiene - enteroviruses live, as the name suggests, in the gastro-intestinal tract). It is also sometimes seen in daycare/kindergarten/preschool workers and in parents of preschoolers. It can be quite debilitating in adults. Coxsackie virus has been associated with Chronic Fatigue Syndrome by British researchers.
A typical course of HFMD infection will last for 7-10 days and resolve spontaneously, but in rare cases complications, including cardiac difficulties and encephalitis, may arise. The painful ulceration of the mouth may also interfere with the breast-feeding of smaller children.
Hand-Foot-Mouth disease should not be confused with Foot and Mouth disease, which is an animal disease caused by an unrelated virus.
As I write this, I'm suffering from HFMD for the second time in two years, a clear case of the kindergarten plague - children are unsanitary little walking timebombs of infection, and no adults are more frequently ill than parents. My mouth hurts, my throat hurts, and everything tastes like it had been dipped in black pepper. Oh, the humanity!
Update, october 2004: Hello again, Mr. HFMD virus. Nice to meet you, for the fourth effin' time.