Parainfluenza Virus 1, 2, 3, 4

  • Diagnosis
  • Background
  • Lab Tests
  • References
  • Related Topics

Indications for Testing

  • Flu-like illness during parainfluenza virus (PIV) season

Laboratory Testing

  • Clinical features and diagnosis of parainfluenza viruses (CDC)
  • Clinical diagnosis usually suffices
  • Direct fluorescent antibody (DFA) – rapid testing; may be useful during epidemics to rule out influenza
    • Nasopharyngeal aspirates for viral testing of specimens
    • Consider DFA for all of the following concurrently – influenza, adenovirus, RSV, and hMPV
    • Less sensitive than culture, polymerase chain reaction (PCR)
  • PCR – most sensitive; some assays can detect parainfluenza 4
  • Sequential panel antibody testing
    • Supports diagnosis
    • Cross reactivity can occur with assays for IgG, particularly due to mumps virus
    • Usually not necessary, except possibly during epidemic events
  • Viral culture – gold standard
    • Conventional culture requires up to 7 days
    • Rapid culture requires less time (24-48 hours)
  • Consider additional testing for other atypical/bacterial organisms
  • CBC – may be helpful in moderately to severely ill patients if differential diagnosis includes bacterial disease


  • Chest x-ray – rule out pneumonia in moderately ill patients

Differential Diagnosis

Parainfluenza viruses (PIV) are the second most common cause of acute upper and lower respiratory tract infections (URI and LRTI) in the U.S. for children <5 years.


  • Prevalence
    • PIV cause 65% of croup cases, 20-40% of LRTIs and 20% of URIs in preschool children
    • 3/1,000 cases of laryngotracheobronchitis (croup) require medical attention per year
  • Age – usually children 3-5 years
  • Transmission – respiratory droplet


  • PIV types 1, 2, and 3 – clinically the most common
    • Types 1 and 2 – primary causes of croup
      • Seasonal biennial outbreaks in the U.S. – currently occurring in the fall of odd-numbered years
    • Types 1 and 3 – common in early childhood; causes localized outbreaks in nurseries, schools, orphanages, pediatric wards
    • Type 3 – second only to respiratory syncytial virus (RSV) as a cause of bronchiolitis and pneumonia in infants
      • Can cause parotiditis similar to mumps
      • Peak is late spring
    • Type 4 – less well-studied but also causes URI and LRTI


  • Enveloped, single-stranded RNA virus belonging to the Paramyxoviridae family
  • Other viruses in this family include RSV, mumps, measles, metapneumovirus (hMPV), Hendra and Nipah viruses

Clinical Presentation

  • May present as mild upper respiratory illness, croup, bronchiolitis, or pneumonia
    • Older children and adults tend to have milder disease
Tests generally appear in the order most useful for common clinical situations. Click on number for test-specific information in the ARUP Laboratory Test Directory.

Respiratory Viruses DFA with Reflex to Viral Culture, Respiratory 0060281
Method: Direct Fluorescent Antibody Stain/Cell Culture


Sensitivity of DFA methodology is dependent on the adequacy of the specimen

Parainfluenza 1-4 by RT-PCR 2006247
Method: Qualitative Polymerase Chain Reaction

Viral Culture, Respiratory 2006499
Method: Cell Culture


Slow growth; not ideal for acute identification

Respiratory Viruses Rapid Culture 2001504
Method: Cell Culture/Immunofluorescence


Other viruses such as HSV or CMV are not routinely detected in this culture

Decreased sensitivity for detection of adenovirus

Human metapneumovirus is not detected

General References

Ruuskanen O, Lahti E, Jennings LC, Murdoch DR. Viral pneumonia. Lancet. 2011; 377(9773): 1264-75. PubMed

Sato M, Wright PF. Current status of vaccines for parainfluenza virus infections. Pediatr Infect Dis J. 2008; 27(10 Suppl): S123-5. PubMed

Weinberg GA. Parainfluenza viruses: an underappreciated cause of pediatric respiratory morbidity. Pediatr Infect Dis J. 2006; 25(5): 447-8. PubMed

References from the ARUP Institute for Clinical and Experimental Pathology®

Couturier MR, Barney T, Alger G, Hymas WC, Stevenson JB, Hillyard D, Daly JA. Evaluation of the FilmArray® Respiratory Panel for clinical use in a large children's hospital. J Clin Lab Anal. 2013; 27(2): 148-54. PubMed

Medical Reviewers

Last Update: December 2016