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. There is a seasonal pattern in temperate climates with the peak incidence in late summer and early fall. Symptoms such as malaise, low-grade fever and anorexia are often present and occasionally, patients have high fever, marked malaise, diarrhea and athralgias. Enteroviral infections may also cause myocarditis, pneumonia, meningoencephalitis and even death. Rarely, recurrent disease has been seen.