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Viral "bronchitis" in childhood: relationship to asthma and obstructive lung disease
D C Schroeckenstein1, W W Busse
1Department of Medicine, University of Wisconsin, Madison.
Insights
Viral lower respiratory tract infections in children, such as respiratory syncytial virus (RSV) and rhinovirus, can lead to persistent wheezing and asthma. These infections cause airway inflammation, increasing the risk of chronic respiratory issues later in life.
Area of Science:
- Pediatric Pulmonology
- Infectious Diseases
- Immunology
Background:
- Lower respiratory tract infections (LRTIs) in children, including bronchiolitis and bronchitis, are frequently linked to recurrent wheezing.
- Respiratory viruses like respiratory syncytial virus (RSV) and rhinovirus are key pathogens, with prevalence varying by age group.
- Early childhood viral LRTIs are associated with long-term pulmonary abnormalities, potentially leading to adult chronic airway obstruction.
Purpose of the Study:
- To explore the mechanisms by which respiratory viruses trigger asthma in children.
- To understand the link between viral infections in early life and the development of chronic airway diseases.
Main Methods:
- Review of epidemiologic studies and identified mechanisms of virus-induced asthma.
- Analysis of the role of specific viruses (RSV, rhinovirus) in different pediatric age groups.
- Examination of the connection between viral LRTIs and subsequent pulmonary abnormalities.
Main Results:
- Viral LRTIs in early childhood are strongly associated with persistent bronchial hyperreactivity and airway obstruction.
- Respiratory viruses induce asthma through various mechanisms, primarily involving direct or indirect airway inflammation.
- No single mechanism fully explains virus-induced asthma, but airway inflammation is a common pathway.
Conclusions:
- Respiratory viruses are significant contributors to childhood asthma development and exacerbation.
- Early viral LRTIs can establish a predisposition to chronic airway diseases persisting into adulthood.
- Understanding these mechanisms is crucial for developing preventative and therapeutic strategies for pediatric asthma.
Abstract:
Lower respiratory tract infections in children, including group, bronchiolitis, and bronchitis are frequently associated with recurrent episodes of wheezing. Different respiratory viruses assume greater importance at different ages of children. Respiratory syncytial virus is the most prevalent viral respiratory infection in preschool children, while rhinovirus is of increasing importance in older children. Asymptomatic virus shedding and mild respiratory infections do not provoke asthma symptoms nor do bacteria, except in association with sinusitis. Furthermore, epidemiologic studies strongly suggest that viral lower respiratory tract illness in early childhood is associated with pulmonary abnormalities, including bronchial hyperreactivity and peripheral airway obstruction that may persist for many years, and is possibly a cause of chronic airway obstruction in adulthood. Several different mechanisms have been identified by which respiratory viruses provoke asthma. No one single mechanism, however, adequately explains virus-induced asthma. Nonetheless, a common thread to these various proposed mechanisms is the ability of respiratory viruses to cause airway inflammation, either directly, through cytopathic effects, or indirectly, by increasing the inflammatory processes of respiratory cells. The consequence of these effects causes increased airway responsiveness and asthma.