Most commonly, the etiologic agents are coxsackieviruses, members of the picornaviridae. Epidemic viral infections are usually caused by members of the enterovirus family, coxsackievirus A16 or enterovirus 71.
Infections usually occur as isolated events, but epidemics occur regularly.
The incubation period averages 3-6 days. Coxsackievirus is highly contagious, and during epidemics the virus is spread horizontally from child to child and from mother to fetus. Initial viral implantation in the buccal and ileal mucosa is followed by spread to lymph nodes within 24 hours. Viremia rapidly ensues with spread to oral mucosa and skin. By day 7 rising neutralizing antibody levels clear the virus.