Exposure to environmental microorganisms and childhood asthma
Markus J Ege, Melanie Mayer, Anne-Cécile Normand, Jon Genuneit, William O C M Cookson, Charlotte Braun-Fahrländer, Dick Heederik, Renaud Piarroux, Erika von Mutius, GABRIELA Transregio 22 Study Group, Silvia Apprich, Johann Bauer, Andrzej Boznanski, Charlotte Braun-Fahrländer, Gisela Büchele, William Cookson, Paul Cullinan, Hanna Danielewicz, Anna Dębińska, Martin Depner, Markus Ege, Urs Frey, Oliver Fuchs, Jon Genuneit, Dick Heederik, Elisabeth Horak, Anne Hyvärinen, Sabina Illi, Michael Kabesch, Katalin Kovacs, Aleksandra Kosmęda, Wolfgang Kneifel, Philipp Latzin, Roger Lauener, Georg Loss, Stephanie J MacNeill, Melanie Mayer, Bernhard Morass, Anne-Cécile Normand, Ilka Noss, Göran Pershagen, Renaud Piarroux, Harald Renz, Helena Rintala, Mascha K Rochat, Karin Schwaiger, Nikolaos Sitaridis, Barbara Sozanska, David Strachan, Christine Strunz-Lehner, Bertrand Sudre, Erika von Mutius, Marco Waser, Juliane Weber, Inge Wouters, Markus J Ege, Melanie Mayer, Anne-Cécile Normand, Jon Genuneit, William O C M Cookson, Charlotte Braun-Fahrländer, Dick Heederik, Renaud Piarroux, Erika von Mutius, GABRIELA Transregio 22 Study Group, Silvia Apprich, Johann Bauer, Andrzej Boznanski, Charlotte Braun-Fahrländer, Gisela Büchele, William Cookson, Paul Cullinan, Hanna Danielewicz, Anna Dębińska, Martin Depner, Markus Ege, Urs Frey, Oliver Fuchs, Jon Genuneit, Dick Heederik, Elisabeth Horak, Anne Hyvärinen, Sabina Illi, Michael Kabesch, Katalin Kovacs, Aleksandra Kosmęda, Wolfgang Kneifel, Philipp Latzin, Roger Lauener, Georg Loss, Stephanie J MacNeill, Melanie Mayer, Bernhard Morass, Anne-Cécile Normand, Ilka Noss, Göran Pershagen, Renaud Piarroux, Harald Renz, Helena Rintala, Mascha K Rochat, Karin Schwaiger, Nikolaos Sitaridis, Barbara Sozanska, David Strachan, Christine Strunz-Lehner, Bertrand Sudre, Erika von Mutius, Marco Waser, Juliane Weber, Inge Wouters
Abstract
Background: Children who grow up in environments that afford them a wide range of microbial exposures, such as traditional farms, are protected from childhood asthma and atopy. In previous studies, markers of microbial exposure have been inversely related to these conditions.
Methods: In two cross-sectional studies, we compared children living on farms with those in a reference group with respect to the prevalence of asthma and atopy and to the diversity of microbial exposure. In one study--PARSIFAL (Prevention of Allergy-Risk Factors for Sensitization in Children Related to Farming and Anthroposophic Lifestyle)--samples of mattress dust were screened for bacterial DNA with the use of single-strand conformation polymorphism (SSCP) analyses to detect environmental bacteria that cannot be measured by means of culture techniques. In the other study--GABRIELA (Multidisciplinary Study to Identify the Genetic and Environmental Causes of Asthma in the European Community [GABRIEL] Advanced Study)--samples of settled dust from children's rooms were evaluated for bacterial and fungal taxa with the use of culture techniques.
Results: In both studies, children who lived on farms had lower prevalences of asthma and atopy and were exposed to a greater variety of environmental microorganisms than the children in the reference group. In turn, diversity of microbial exposure was inversely related to the risk of asthma (odds ratio for PARSIFAL, 0.62; 95% confidence interval [CI], 0.44 to 0.89; odds ratio for GABRIELA, 0.86; 95% CI, 0.75 to 0.99). In addition, the presence of certain more circumscribed exposures was also inversely related to the risk of asthma; this included exposure to species in the fungal taxon eurotium (adjusted odds ratio, 0.37; 95% CI, 0.18 to 0.76) and to a variety of bacterial species, including Listeria monocytogenes, bacillus species, corynebacterium species, and others (adjusted odds ratio, 0.57; 95% CI, 0.38 to 0.86).
Conclusions: 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. (Funded by the Deutsche Forschungsgemeinschaft and the European Commission.).
Source: PubMed