<prompt> Most common cause of infectious croup isAdenovirusParainfluenza type IRSVInfluenza  <response>: Ans. is b i.e., Parainfluenza type I Infectious croup Laryngitis laryngotracheobronchitiso Nearly always caused by viral infectiono Usually by parainfluenza type I.o Other-RSVParainfluenza 2,3InfluenzaAdenoviruso TreatmentHumidified oxygenIntravenous fluid for adequate hydrationAntibiotic ampicillin ceftriaxone if suspecting epiglottitis. 