Published Online: December 5, 2014
It is well recognized that the majority of severe asthma attacks in children are linked to viral infections. However, it is less clear whether day-to-day asthma symptoms are also affected by viral infections circulating in the community, and whether other factors might change the risk of symptoms at this time. These questions have been addressed recently in The Journal of Allergy and Clinical Immunology (JACI), where Tovey and colleagues present the results of a study in which children’s asthma symptoms and virus infections were routinely sampled over an extended period of time.
The authors recruited 67 children, aged 5-12 years old, with a history of one or more hospital visits for their asthma. Using questionnaires, the children recorded information on their medication use and asthma and cold symptoms, and sampled both nasal mucus and exhaled breath, twice-weekly, for 10 weeks each. These samples were analyzed for a range of viruses. Information on other factors such as the types of virus, presence of allergy, allergen exposure, vitamin D status, and types of medication being used was collected to determine whether these affected the response to viruses.
The results showed that virus infections were very common, occurring in one third of the samples of either nasal wash or exhaled breath. The presence of virus in the nasal wash, but not in the exhaled breath, was associated with a two-fold increase in asthma and cold symptoms. The specific type of virus, and environmental factors had little or no effect on the relationship of virus infection to asthma symptoms.
This study suggests that virus infections commonly circulating in the community are not only an important cause of asthma attacks, but also contribute to day-to-day variation in asthma symptoms. As there are no proven, practical ways to entirely prevent such respiratory viral infections, future studies need to explore what makes some occasional virus infections cause acute and severe asthma attacks, while most viral infections are only associated with a small increase in the risk of symptoms.
The Journal of Allergy and Clinical Immunology (JACI) is an official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.