Rhinovirus infections in infancy and early childhood

Rhinovirus (RV) infections occur early and recurrently in life, imposing a significant burden of disease on infants and young children. They are the most frequent causative agents of both upper and lower respiratory tract infections in this age group and are associated with a broad variety of clinical outcomes, ranging from asymptomatic infections to severe respiratory disease requiring hospitalisation. In addition to their impact on short-term morbidity, RVs are also debated as important pathogens in the development of recurrent wheeze and/or asthma. Several studies in infants at high-risk for atopy and asthma and in hospitalised children have demonstrated that recurrent wheezing illnesses induced by RVs early in life are a risk factor for the development of asthma later in childhood. However, underlying mechanisms are poorly understood. The question whether RVs are directly involved in the development of childhood wheeze and asthma, or whether symptomatic RV infections only represent a proxy for infants prone to develop obstructive lung diseases, is still open. In this review we provide an overview on the role of RVs as important disease-causing agents from infancy to early childhood and discuss their contribution to the subsequent development of childhood wheeze and/or asthma.

Dynamics of the nasal microbiota in infancy: A prospective cohort study.

BACKGROUND Understanding the composition and dynamics of the upper respiratory tract microbiota in healthy infants is a prerequisite to investigate the role of the microbiota in patients with respiratory diseases. This is especially true in early life, when the immune system is in development. OBJECTIVE We sought to describe the dynamics of the upper respiratory tract microbiota in healthy infants within the first year of life. METHODS After exclusion of low-quality samples, microbiota characterization was performed by using 16S rDNA pyrosequencing of 872 nasal swabs collected biweekly from 47 unselected infants. RESULTS Bacterial density increased and diversity decreased within the first year of life (R(2) = 0.95 and 0.73, respectively). A distinct profile for the first 3 months of life was found with increased relative abundances of Staphlyococcaceae and Corynebacteriaceae (exponential decay: R(2) = 0.94 and 0.96, respectively). In addition, relative bacterial abundance and composition differed significantly from summer to winter months. The individual composition of the microbiota changed with increasing time intervals between samples and was best modeled by an exponential function (R(2) = 0.97). Within-subject dissimilarity in a 2-week time interval was consistently lower than that between subjects, indicating a personalized microbiota. CONCLUSION This study reveals age and seasonality as major factors driving the composition of the nasal microbiota within the first year of life. A subject's microbiota is personalized but dynamic throughout the first year. These data are indispensable to interpretation of cross-sectional studies and investigation of the role of the microbiota in both healthy subjects and patients with respiratory diseases. They might also serve as a baseline for future intervention studies.

Effects of Breastfeeding on Respiratory Symptoms in Infancy.

OBJECTIVE To assess the impact of potential risk factors on the development of respiratory symptoms and their specific modification by breastfeeding in infants in the first year of life. STUDY DESIGN We prospectively studied 436 healthy term infants from the Bern-Basel Infant Lung Development cohort. The breastfeeding status, and incidence and severity of respiratory symptoms (score) were assessed weekly by telephone interview during the first year of life. Risk factors (eg, pre- and postnatal smoking exposure, mode of delivery, gestational age, maternal atopy, and number of older siblings) were obtained using standardized questionnaires. Weekly measurements of particulate matter <10 μg were provided by local monitoring stations. The associations were investigated using generalized additive mixed model with quasi Poisson distribution. RESULTS Breastfeeding reduced the incidence and severity of the respiratory symptom score mainly in the first 27 weeks of life (risk ratio 0.70; 95% CI 0.55-0.88). We found a protective effect of breastfeeding in girls but not in boys. During the first 27 weeks of life, breastfeeding attenuated the effects of maternal smoking during pregnancy, gestational age, and cesarean delivery on respiratory symptoms. There was no evidence for an interaction between breastfeeding and maternal atopy, number of older siblings, child care attendance, or particulate matter <10 μg. CONCLUSIONS This study shows the risk-specific effect of breastfeeding on respiratory symptoms in early life using the comprehensive time-series approach.