Virus
Parainfluenza virus
Leading cause of croup in children
PAIR-uh-in-floo-EN-zuh VY-rus
High-yield clue
A barking (seal-like) cough and inspiratory stridor from croup (laryngotracheobronchitis) is the classic parainfluenza clue.
Overview
Enveloped negative-sense RNA paramyxoviruses (human types 1-4) that infect the respiratory tract and are the leading cause of croup, useful for linking upper-airway obstruction vocabulary to a viral cause.
Classification
- RNA virus
- Negative-sense single-stranded RNA
- Enveloped, HN and F glycoproteins
- Family Paramyxoviridae (Respirovirus and Orthorubulavirus)
Lab & identification clues
- Respirovirus/Orthorubulavirus classification concept
- Multiplex respiratory PCR panel vocabulary
- Nasopharyngeal sampling concept
- Subglottic narrowing ('steeple sign') imaging vocabulary
Associations
- Croup (laryngotracheobronchitis) in young children
- Also causes bronchiolitis and pneumonia
- Respiratory-droplet and contact spread
- Seasonal outbreak epidemiology
Commonly confused with
- Respiratory syncytial virus
- Human metapneumovirus
Your notes
Original student-study summary. Sources checked: OpenStax Microbiology 2e, NCBI Bookshelf Medical Microbiology, and CDC topic pages where applicable; reviewed 2026-06. Educational only; no diagnosis, treatment, dosing, or specimen-handling guidance.