Four year retrospective analysis of viral nasopharyngeal samples in a pediatric population at a Canadian tertiary care hospital

Background:

Viral respiratory tract illnesses cause a burden of disease in the pediatric population, especially during endemic months.  Disease manifests as a spectrum, from self-limited upper respiratory tract infection, to systemic illness, respiratory failure, secondary bacterial infection, or death.  This is particularly important in the pediatric population who are particularly susceptible to complications.

Objective:

We present a descriptive analysis of  nasopharyngeal samples in pediatric patients at Children’s Hospital of London Health Sciences Centre, a tertiary care centre servicing approximately one million people in southwestern Ontario.  

Methods:

Patients with a suspicion of respiratory virus presenting to hospital for assessment were sampled with a nasopharyngeal swab.  Specimens underwent analysis by Direct Flourescent Antgen, Virus culture, or the Luminex^TM Multiplex PCR Respiratory Virus Panel kit, specific for: Influenza, Adenovirus, Parainfluenza, RSV (Respiratory Syncitial Virus), Metapneumovirus, Corona virus, Rhinovirus, and Boca virus.   A database of positive samples was created and analyzed with respect to temporal trends, demographics, and disease prevalence.

Results:

A total of 779 cases were identified from Oct 2006 to July 2010.  Most cases were under 5 years of age, with 9.6% (75) under 30 days, 45.7% (356) between 30 days and 1 year, and 26.8% (209) between 1 year and 5 years of age.  The majority of cases were also admitted to hospital (87.3%) and a subset of 12.6% requiring critical care. Incidence increased yearly, with 38.1% of cases (297) identified in 2010.  RSV was predominant (456 isolates), with influenza a/b (120 isolates), rhinovirus (78 isolates), parainfluenza (69 isolates), and the remaining 100 isolates consisting of other respiratory viruses.  A subset of 6% of cases had more than one virus isolated. 

Conclusions:

Respiratory viruses tended to affect younger populations, and lead to inpatient care in many cases.  There was a rising incidence in cases per year, which may be due to more infections, as well as the increased clinical suspicion due to the emergence of H1N1.  RSV and influenza were the leading isolates found on analysis.  Further investigation into clinical course of patients, as well as data on ambulatory settings would help to characterize the burden of illness.  However, this analysis notes our experience with detection of respiratory viruses over a four year period.