Parainfluenza virus infections.
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D002648:Child; D002675:Child, Preschool; D003440:Croup / Q000209:etiology; D005194:Family Practice; D006761:Hospitals; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008875:Middle Aged; D012140:Respiratory Tract Diseases / Q000382:microbiology*; D018108:Respirovirus / Q000302:isolation & purification