The type of bronchiolitis matters in the asthma development
Published online: September 11, 2019
Bronchiolitis is one of the leading reasons for hospitalization among infants. Respiratory syncytial virus (RSV) is the most frequent cause of this infection, but other viruses, especially rhinovirus, are also detected. The rhinovirus is classified into types A, B and C, which seem to associate differently with the severity of the infection. Severe bronchiolitis is further considered a risk factor for future asthma, but it is unclear if the rhinovirus types involved with bronchiolitis have different risk associated with the development of asthma. In addition, whether it is the rhinovirus infection itself or the immunological responses of the child, which primarily enhances the development, is still partly unknown.
In a recent article published in The Journal of Allergy and Clinical Immunology: In Practice Bergroth and colleagues investigated whether RSV or rhinovirus types are differently associated with the use of long-term asthma control medication during the following four years after severe bronchiolitis in infancy. During two consecutive winter seasons from 2008 to 2010, over 400 children (all less than 24 months of age) hospitalized for bronchiolitis were enrolled in the study from the pediatric and intensive care wards of 3 university hospitals in Finland. Nasal wash samples were taken to establish the viral etiology of the bronchiolitis. Four years later, the use of asthma control medication after bronchiolitis was determined with a questionnaire.
Severe bronchiolitis caused by rhinovirus type A and C was associated with earlier initiation and prolonged use of asthma control medication. Four years after hospitalization, 47% of the patients with rhinovirus bronchiolitis used asthma control medication, when only 15% of those with former RSV bronchiolitis were still using medication. The risk for the use of medication was especially high among patients with type C rhinovirus, atopic dermatitis and fever at the time of hospitalization.
In summary, the results highlight the view that bronchiolitis should be looked at a new way: instead of a uniform entity, it should be seen as a disease with subgroups that have different risk factors and genetic background with dissimilar response to treatment and distinct prognosis. If this is all confirmed in further trials, testing for viral etiology of bronchiolitis could be recommended in forthcoming treatment guidelines to better estimate the future risk for developing asthma. The study also suggests that a preventive strategy targeting either rhinovirus type A or especially C might help to prevent at least some types of childhood asthma.
The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.