Microbial Exposure May Protect Against Asthma
Prevalence of asthma, atopy lower in children living on farms, who have higher microbial exposure
WEDNESDAY, Feb. 23 (HealthDay News) -- There appears to be an inverse relationship between asthma and exposure to a wide variety of microbes, according to comparative analyses of children who grow up on farms and those who do not; the results have been published in the Feb. 24 issue of the New England Journal of Medicine.
Markus J. Ege, M.D., of the University Children's Hospital Munich in Germany, and colleagues conducted two cross-sectional studies comparing the prevalence of asthma and atopy in children living on farms and in a reference group. Their objective was to test the inverse association between microbial exposure and asthma and atopy previously reported. In one study, they screened samples of mattress dust for bacterial DNA. In the other, they evaluated samples of dust from children's rooms for bacterial and fungal taxa.
In both studies, the researchers found a lower prevalence of asthma and atopy in farm-dwelling children and found that these children were exposed to a greater range of environmental microorganisms than children in the reference group. Diversity of microbial exposure was inversely related to risk of asthma (odd ratios, 0.62 for the first study and 0.86 for the second study). The presence of some more circumscribed exposures was also inversely associated with the risk of asthma. This included exposure to species in the fungal taxon eurotium and to several bacterial species.
"Children living on farms were exposed to a wider range of microbes than were children in the reference group, and this exposure explains a substantial fraction of the inverse relation between asthma and growing up on a farm," the authors write.
One study author disclosed financial relationships with pharmaceutical companies, including GlaxoSmithKline and Novartis. The editorial author disclosed financial relationships with several biotechnology and pharmaceutical companies.