S. TRACY Late in the 1940s, a virus was isolated from a young patient with a flaccid par- alysis in the sleepy Hudson River town of Coxsackie in the state of New York. Within the next few years, it was apparent that this and other similar viruses were not polioviruses but were indeed a new group of viruses, viruses that by the mid- 1950s had been found to be commonly associated with pediatric inflammatory heart disease. Two groups of coxsackieviruses (A and B) were differentiated on the basis of the type of paralysis induced in suckling mice by these viruses. Group B coxsackieviruses, because...