During the summer of 1948, an unusual number of patients with illnesses resembling nonparalytic poliomyelitis were admitted to hospitals in the southern part of New England. Similar cases had also been noted in the previous year in this area as well as elsewhere.1 Evidence had been obtained that the illness in some of the patients was caused by strains of poliomyelitis virus.2
It seemed possible, however, that not all the patients had poliomyelitis but that some of the mild, nonparalytic illnesses might have been caused by a different infectious agent. In order to explore this possibility, information was sought concerning the distribution of paralytic and nonparalytic cases in the southern part of New England during 1948, and certain representative patients were studied to determine whether poliomyelitis virus or some other agent could be shown to be causative of their illnesses.
As reported elsewhere, strains of a filtrable virus,