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Monday, March 8, 2010

Fungal exposure and inner-city children

In another effort to pin down factors that increase asthma morbidity in inner-city children, Pongracic et al. report results from their study of effects of indoor and outdoor fungal exposure in children with asthma and fungal sensitivity. The authors use a subset of children from the Inner City Asthma Study (ICAS) with positive skin tests to at least one of four fungi: Alternaria, Cladosporium, Penicillium, and Aspergillus (mixed species). Indoor and outdoor fungal sampling was performed every six months for 2 years. Questionnaires were administered by phone every 2 months collecting data about number of symptom days, nighttime awakening due to asthma, number of days the child’s activities were limited by asthma, missed school days, and ED and unscheduled doctor visits.

Compared to other subjects in the ICAS who had negative skin tests to fungi, the fungi-sensitive children had significant increases of number of symptomatic days and unscheduled clinic or ED visits on days when total combined fungal exposure was increased. Increased indoor fungal exposure was associated significantly with unscheduled visits, with Pencillium exposure having the most profound effect.

Pongracic and colleagues also report effects of specific fungal exposure in children that had negative skin tests to one or more of the 4 fungal extracts tested, but with at least one positive skin test to a fungal allergen. Increased outdoor exposure to Alternaria and Penicillium in children not sensitized to either was found to increase the number of symptomatic days, while increased indoor exposure to Penicillium was associated with increased medical visits, which is similar to the finding in children sensitive to Pencillium.

The authors discuss several limitations associated with their research. Sampling technique did not include collection of indoor floor dust samples, and was of short duration during low-activity periods in the home. The fungal sampling design did not include sampling in the homes of unsensitized children. Outdoor sample collection was short duration and episodic, which might not reflect fungal counts over a long period of time. Additionally, the finding of increased impairment among children not sensitized to one or more of the fungi used in the skin testing confounds the outcomes on numerous levels.

Dr. Pongracic shared the following comments with us:

“It is our hope that these findings, which have shed light on the role of outdoor and indoor fungi in asthma morbidity among inner-city children, will lead us and others to several avenues of clinical and translational investigation. Future directions include (1) environmental interventions directed against fungi and their ability to reduce asthma exacerbations and to improve asthma control; (2) mechanistic studies of the health effects of fungi on non-sensitized individuals; (3) development of novel methodologies to assess ongoing fungal allergen exposure; (4) exploration of viral-fungal allergen and pollutant-fungal allergen interactions as they pertain to asthma exacerbations in urban populations; and (5) performing similar studies of other populations, including suburban and rural children, to ascertain whether these relationships exist beyond the inner city.

There are a variety of opportunities to extend these findings to clinical practice. Certainly, assessment of the inner-city child with asthma should include investigation for sensitization to multiple fungal allergens, through skin testing or in vitro testing. Our findings should also prompt health care providers to not only consider cockroach, mouse and dust mite allergens in their assessment of the home environment but also fungal allergens. Given the extensive use of cellphones among inner-city families and the widespread availability of digital camera functionality on these phones, individuals could be instructed to photograph household conditions that promote/reveal mold growth to help identify specific sources of problems and inform potential interventions. Broader education should be instituted regarding understanding risk factors for household mold contamination, how to identify it when it occurs and how to intervene. Public service announcements for notification of periods of high concentrations of outdoor airborne fungi could be an efficient and effective means to inform people of potential increased exposures and to recommend keeping windows closed to reduce indoor entry of fungal allergens.”

We want to hear from you. Please feel free to post your own questions or comments below. All questions and comments will be forwarded to the authors for a response.

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