Parainfluenza Virus 1, 2, 3

Parainfluenza Virus 1, 2, 3

 

Parainfluenza viruses (PIV) are the second most common cause of acute upper (URI) and lower (LRI) respiratory tract infections in children younger than 5 years of age in the U.S.

Epidemiology

  • Incidence
    • PIV causes 65% of croup cases, 20-40% of LRIs and 20% of URIs in preschool children
    • 3/1000 cases of croup require medical attention per year
  • Age
    • Most common in children ages 3 to 5
  • Transmission
    • Via droplet

Classification

  • Types 1, 2, and 3 are clinically the most common
    • Types 1 and 2 are the primary causes of laryngotracheobronchitis (croup)
      • Occurs seasonally in the fall of odd-numbered years
    • Types 1 and 3 are common in early childhood, causing localized outbreaks in nurseries, schools, orphanages, and pediatric wards
    • Type 3 is second only to respiratory syncytial virus as a cause of bronchiolitis and pneumonia in infants
      • Can cause parotids similar to mumps
      • Peak is late spring
    • Type 4 is rare

Organism

  • An enveloped and single-stranded RNA virus that belongs to the Paramyxoviridae family
  • Other viruses in this family include RSV, mumps, measles, Hendra and Nipah viruses

Clinical Presentation

  • Symptoms vary from mild upper respiratory illness to severe pneumonia
  • Older children and adults tend to have milder disease

Diagnosis

  • Laboratory testing
    • Clinical diagnosis usually suffices
    • Sequential panel antibody testing supports the diagnosis

Treatment

  • Treatment is symptomatic and supportive.

See Also