Clinical Background
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
- Prevalence
- 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 respiratory 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 parotiditis similar to mumps
- Peak is late spring
- Type 4 is rare and typically causes minor URI
- Types 1 and 2 are the primary causes of laryngotracheobronchitis (croup)
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
Treatment
- Treatment is symptomatic and supportive.
See Also
