Cytopathogenic Myxovirus with Infantile Croup

At the present time most infectious croup in infancy, seems to be unrelated to Corynebacterium diphtheriae or Hemophilus influenzae B; moreover recent studies have failed to implicate other pathogenic bacteria (1). The term "viral croup" has been applied to this syndrome without the necessary justification of an etiologically associated viral agent. The purpose of the present s tudy was to determine whether cytopathogenic agents could be isolated from infants with croup and, if so, to assess their importance in the causation of the observed disease. During the course of this work 2 viruses, which produced an unusual cytopathogenic effect, were isolated in tissue culture of monkey kidney epithelium. Characterization of these viruses, which appear to be new members of the myxovirus group, forms the basis of the present report.