Influenza and parainfluenza associated pediatric ICU morbidity.

Objectives: To investigate if morbidity in young children admitted to a pediatric intensive care unit (PICU with a laboratory proven diagnosis of influenza and parainfluenza infection) had increased.

Methods: Retrospective study from January 2003 through December 2009 was carried out. Every child in the PICU with a laboratory-confirmed influenza or parainfluenza infection was included.

Results: 18 influenza (influenza A =13 and influenza B = 5) and 17 parainfluenza admissions were identified over the 7-year period. Parainfluenza type 3 (n = 9) was the commonest subtype of parainfluenza infection. The median age of children admitted with influenza was higher than parainfluenza (4.5 vs 1.7 years, p = 0.044). Admissions associated with proven influenza and parainfluenza infections accounted for 2% of PICU annual admissions. There was only one death in 2003. 51% of these patients required ventilatory support, 45% received systemic corticosteroids, and 91% received initial broad spectrum antibiotic coverage. Bacterial co-infections were identified in 25% of these patients. The incidence of influenza admissions had not increased significantly in 2009 (H1N1 pandemic) when compared with 2003 (SARS epidemic) (p = 0.3). There were only two PICU cases of pandemic H1N1 in 2009 and both survived. The annual incidence of severe PICU cases of influenza and parainfluenza were 0.94 and 0.88 per 100,000 children per annum, respectively.

Conclusions: Pandemic H1N1, influenza and parainfluenza viruses may be associated with significant childhood morbidity and PICU admissions.