title: Croup associated with parainfluenza type 1 virus: two subpopulations.
mesh_terms: D002675:Child, Preschool; D003440:Croup / Q000145:classification* / Q000209:etiology; D006801:Humans; D007827:Laryngitis / Q000145:classification*; D010222:Parainfluenza Virus 1, Human; D018184:Paramyxoviridae Infections; D013997:Time Factors