ASTHMA: ENVIRONMENTAL ALLERGENS |
Clinical Importance of Alternaria Exposure in Children
Indianapolis, IN
Purpose of the Study. To investigate the extent to which exposure to Alternaria increases the severity of asthma.
Study Population. The study included 399 children from 2 inland Australian rural towns. All those children who had a positive skin test to the mold Alternaria were enrolled (n = 179) and random samples of children from each town who were allergic, but not to Alternaria, were recruited as the allergic control group. The average age of the children in both groups was 9.1 years.
Methods. This was a prospective cohort study. The 2 groups of children were assessed 5 times over 22 months. Questionnaires were used asking about respiratory symptoms in the month before the assessment. Airway hyperresponsiveness was assessed with histamine provocation challenges. The dose-response ratio (DRR) was used to measure the level of airway responsiveness and airway hyperreactivity (AHR) was defined as a 20% drop in forced expiratory volume in 1 second (FEV1) at or before the maximum provocation dose. Mold spores were measured throughout the study period. Four respiratory outcomes were used: DRR, AHR, wheeze, and bronchodilator use.
Results. There was a wide range of mold concentrations, from an average low of 2.2 spores/cubic meter of air/day to an average maximum of 307.7 spores/cubic meter/day. The highest count was 1270 spores. These mold spore counts correlated with increased temperature and grass pollen counts. Those children who had sensitization to Alternaria also had increased sensitization to another mold, Cladosporium, mixed grain, and cat dander. Sensitization to dust mites was less common in those sensitive to Alternaria. Children who were sensitive to Alternaria were more likely to have airway hyperresponsiveness. The presence of AHR was also significantly associated with mold spore concentrations. The odds ratio for AHR at a level of 100 mold spores was 1.26. The level of airway hyperresponsiveness or DRR was significantly associated with sensitization to Alternaria and to the concentration of the spore in the air. The odds ratio at 100 spores was 1.14. The proportion of children with complaints of wheeze and the number of children who needed to use a bronchodilator increased with increasing mold concentration.
Conclusion. The severity of airway hyperresponsiveness increased with increasing Alternaria spore concentrations more significantly in those children who were sensitized to Alternaria.
Reviewer’s Comments. Molds are a current topic of great concern. In the media, there are frequent reports of how molds are affecting health. This article, as the author states, is the first study to look at the effects of natural exposure to Alternaria in both sensitized and nonsensitized children using an objective measure of airway hyperreactivity. The authors used a population of children who were skin test-sensitive to mold and assessed exposure and a variety of outcome measures. Not only were the children sensitized, but they also had significant exposure to Alternaria. When the spore counts increased, the airways demonstrated significant hyperreactivity, a hallmark feature of asthma. Their airway hyperreactivity was almost twice that of children who were not sensitive to this mold. Sensitivity to Alternaria may be one of those markers for the child with more severe asthma.
REFERENCES
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Downs SH, Mitakakis TZ, Marks GB, et al.
Am J Respir Crit Care Med.2001; 164
:455
–459
PEDIATRICS (ISSN 1098-4275). ©2002 by the American Academy of Pediatrics
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