Associations Between IFI44L Gene Variants and Rates of Respiratory Tract Infections During Early Childhood.

BACKGROUND: Genetic heterogeneity in type I interferon (IFN)-related gene IFI44L may account for variable susceptibility to respiratory tract infections (RTIs) in children. METHODS: In 2 prospective, population-based birth cohorts, the STEPS Study and the FinnBrain Birth Cohort Study, IFI44L genotypes for rs273259 and rs1333969 were determined in relation to the development of RTIs until 1 or 2 years of age, respectively. At age 3 months, whole-blood transcriptional profiles were analyzed and nasal samples were tested for respiratory viruses in a subset of children. RESULTS: In the STEPS Study (n = 1135), IFI44L minor/minor gene variants were associated with lower rates of acute otitis media episodes (adjusted incidence rate ratio, 0.77 [95% confidence interval, .61-.96] for rs273259 and 0.74 [.55-.99] for rs1333969) and courses of antibiotics for RTIs (0.76 [.62-.95] and 0.73 [.56-.97], respectively. In the FinnBrain cohort (n = 971), IFI44L variants were associated with lower rates of RTIs and courses of antibiotics for RTIs. In respiratory virus-positive 3-month-old children, IFI44L gene variants were associated with decreased expression levels of IFI44L and several other IFN-related genes. CONCLUSIONS: Variant forms of IFI44L gene were protective against early-childhood RTIs or acute otitis media, and they attenuated IFN pathway activation by respiratory viruses.

Relapse Among Infants Hospitalized for Bronchiolitis in Finland.

In a prospective cohort of children hospitalized for bronchiolitis, we examined the rate of and characteristics associated with bronchiolitis relapse. Bronchiolitis relapse was documented in 22 (6%) of 391 children, and median time to relapse was 2 (interquartile range, 1-7) days. Relapse occurred more often in males. Prenatal smoking and smoke exposure in the home were also associated with relapse.

Burden of Recurrent Respiratory Tract Infections in Children: A Prospective Cohort Study.

BACKGROUND: The burden of recurrent respiratory infections is unclear. We identified young children with recurrent respiratory infections in order to characterize the clinical manifestations, risk factors and short-term consequences. METHODS: In this prospective cohort study, 1089 children were followed from birth to 2 years of age for respiratory infections by a daily symptom diary. Nasal swabs taken during respiratory infections were analyzed for viruses from 714 children. Nasopharyngeal swabs collected at 2 months of age were cultured for bacteria. The 10% of children with the highest number of annual respiratory illness days were defined to have recurrent respiratory tract infections. RESULTS: The 90th percentile in the number of annual respiratory illness days was 98. Children above this limit (n = 109) had a median of 9.6 acute respiratory infections per year. Rhinovirus was detected in 58% of their infections. Of the children with recurrent infections, 60% were diagnosed with at least 3 episodes of acute otitis media, 73% received at least 3 antibiotic treatments and 21% were hospitalized for an acute respiratory infection. Tympanostomy was performed for 35% and adenoidectomy for 13% of the children. Asthma was diagnosed in 12% by 24 months of age. Older siblings increased the risk of recurrent respiratory infections. Early nasopharyngeal colonization with Streptococcus pneumoniae was common in children who later developed recurrent infections. CONCLUSIONS: Children with recurrent respiratory infections frequently use health care services and antibiotics, undergo surgical procedures and are at risk for asthma in early life. Having older siblings increases the risk of recurrent infections.