Frequency and Duration of Rhinovirus Infections in Children with Cystic Fibrosis and Healthy Controls : A Longitudinal Cohort Study

BACKGROUND: Respiratory viral infections are an important cause of morbidity in patients with chronic respiratory diseases, such as cystic fibrosis (CF). We hypothesized that patients with CF are more susceptible to human rhinovirus (HRV) infections than healthy controls. METHODS: In a 6-months winter period 20 young children with CF (0-7 years) and 18 age-matched healthy controls were sampled bi-weekly for HRV-PCR using nasopharyngeal swabs, irrespective of respiratory symptoms. Respiratory symptoms were scored twice a week. If any symptom was present an additional sample was obtained. All HRV positive samples were genotyped to distinguish HRV subtypes. RESULTS: We analyzed 645 samples, with comparable total numbers of samples in both groups. HRV was detected in 40.8% of all analyzed samples. Children with CF had significantly more HRV positive samples compared to healthy controls, with a mean number (± SD) of 8.1 ± 2.3 versus 5,7 ± 2.9 positive samples per individual (p 2 weeks) with the same HRV subtype occurred more frequently in the CF patients (p<0.01). The genetic distribution and pattern of phylogenetic diversity of the different HRV subtypes was similar in both groups. CONCLUSION: This is the first in vivo longitudinal study showing that HRV is detected more frequently and persists for longer periods in CF patients compared to healthy controls. This might indicate increased viral replication and/or decreased anti-viral defense in patients with CF.