Published Online: March 26, 2012
Infection with respiratory syncytial virus (RSV) is extremely common in early childhood, with nearly all children experiencing at least one such infection before 2 years old. For many years it has been recognized that children with RSV bronchiolitis experience higher than expected rates of wheezing illnesses and asthma later in childhood. However, being able to predict which children with bronchiolitis will be later diagnosed with asthma is not yet possible.
In a recent report in The Journal of Allergy and Clinical Immunology (JACI), Bacharier et al examined the factors which may help identify which children with RSV bronchiolitis develop asthma in early childhood. They enrolled 206 previously babies who were hospitalized with RSV bronchiolitis during the first year of life and followed them prospectively through the seventh birthday. The researchers analyzed clinical and laboratory data obtained during the first three years of life in an effort to predict which children would be diagnosed with asthma.
Nearly half of the children (48%) had asthma diagnosed by a physician by 7 years old. The following factors identified children at increased risk of a physician diagnosis of asthma: having a mother with asthma, being exposed to high levels of dog allergen in the home during the first year of life, having a positive skin test to an inhalant allergen at 3 years old, having multiple wheezing episodes during the first three years of life, and/or having higher levels of a marker of inflammation (chemokine (C-C motif) ligand 5 or CCL5) in epithelial cells obtained from the nose during the episode of bronchiolitis. In contrast, Caucasian children were less likely to have an asthma diagnosis than non-Caucasian children, and those who attended daycare also were less likely to be diagnosed with asthma.
These findings confirmed the high rate of asthma following severe RSV bronchiolitis requiring hospital care and identified several factors which helped identify children at greatest risk for subsequent asthma. In addition, the authors found that the level of CCL5 in nasal cells during bronchiolitis was strongly predictive of asthma, even more so than having a positive family history of asthma.
The Journal of Allergy and Clinical Immunology (JACI) is the official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.