Objectives: Recent studies have suggested the importance of environmental exposure, protective or harmful, in the development of allergic diseases. At-risk or protective microorganism thresholds are not available for any species, and the impact of exposure to multiple antigens has been poorly studied up to now. The ELFE cohort was initiated (French longitudinal childhood study) with multi-disciplinary objectives including assessment of environmental exposure to microorganisms and other allergens at home. Methods: Sampling was performed using Electrostatic Dust collectors (EDC) in the dwellings of 3193 children (nested EBRA cohort) at the time of their birth (2011). EDC were analyzed by quantitative PCR using a panel of 20 targets chosen for their allergic or protective effect for allergic diseases: 9 molds (Alternaria alternata, Aspergillus fumigatus, Aspergillus versicolor, Cladosporium sphaerospermum, Penicillium chrysogenum, Stachybotrys chartarum, Trichoderma viride, Chaetomium globosum, Epicoccum nigrum), 3 bacteria groups (Enterobacteria, Mycobacteria et Streptomyces spp.), 4 dust mites (Dermatophagoides spp., D. pteronyssinus, D. farinae, Acarus siro), 1 yeast (Cryptococcus spp.), and cats, dogs and cockroach allergens. Questions about the baby respiratory symptoms at 2 month (as wheezing, cought, respiratory troubles) were compared to individual concentration of antigens in dwellings. Results: Individual qPCR targets analysis showed that 9 microorganisms were distributed according to different geographical gradients in France (i.e. E. nigrum N-E to S-W, A. alternata N-W to S-W, Dermatophagoïdes E to W). Cockroaches were detected in 9% of dwellings (especially in Eastern France). Dog and cat allergens were detected respectively in 79% and 45% of dwellings. The prevalence of wheezing was 6.5% and prevalence of cough was 25.4%. First univariated statistical analyses showed that Mycobacteria were linked to respiratory troubles reported by parents and quantities of Enterobacteria linked to parents who reported that baby wake up in the night. But, multivariate analyses showed that a restricted panel of 11 qPCR targets made possible to established three house profiles. The profiles are globally distributed on the French territory according to a geographical East-West gradient, which closely matches with the distribution of asthma wheezing in France (Delmas et al., 2012). The zone including the largest number of children with wheezing (West) correspond to home more contaminated in dust mites, molds and bacteria. The next ongoing analysis will be to link respiratory phenotypes of EFLE children and their evolution with selected microorganism’s assemblage. Conclusion: This study reflects the complexity of exposure to the indoor environment and provides an assessment of the contamination of French dwellings in micro-organisms and other allergens with a single standardized quantification method. This approach is promising and should help to explain the occurrence of respiratory diseases in children.
Full conference title:
- TIMM 8th (2017)