Synonyms : Acute Laryngotracheo-Bronchitis Virus, Croup-Associated Viruses, Para-Influenza Virus Type 2, Parainfluenza Virus Type 2, Virus, Croup-Associated, Viruses, Croup-Associated, Acute Laryngotracheo-Bronchitis Viruses, Acute Laryngotracheobronchitis Viruses