Bacteria and mould components in house dust and children's allergic sensitization

¹ Utrecht University, Institute for Risk Assessment Sciences, Utrecht, The Netherlands; and GSF - National Research Center for Environment and Health, Institute of Epidemiology, Neuherberg, Germany
² GSF - National Research Center for Environment and Health, Institute of Epidemiology, Neuherberg, Germany
³ Utrecht University, Institute for Risk Assessment Sciences, Utrecht, The Netherlands
⁴ Karolinska Institutet, Institute of Environmental Medicine, Stockholm, Sweden; and Stockholm County Council, Dept of Occupational and Environmental Health, Stockholm, Sweden
⁵ University of Groningen, University Hospital Groningen, Dept of Paediatric Respiratory Medicine, Groningen, The Netherlands
⁶ Erasmus University, Dept of paediatrics, Division of Respiratory Medicine, Rotterdam, The Netherlands; and Sophia Children's Hospital, Rotterdam, The Netherlands
⁷ RIVM-National Institute for Public Health and the Environment, Center for Prevention and Health Services Research, Bilthoven, The Netherlands
⁸ GSF - National Research Center for Environment and Health, Institute of Epidemiology, Neuherberg, Germany; and Ludwig-Maximilians University of Munich, Institute of Medical Data Management, Biometrics and Epidemiology, Chair of Epidemiology, Munich, Germany
⁹ Utrecht University, Institute for Risk Assessment Sciences, Utrecht, The Netherlands; and University Medical Center Utrecht, Julius Center for Health Sciences and Primary Care, Utrecht, The Netherlands

^* To whom correspondence should be addressed. E-mail: U.Gehring{at}iras.uu.nl.

	Abstract

It has been suggested that early childhood exposure to microbial agents decreases the risk of allergies in children. We studied the association between microbial agents in house dust and allergic sensitization at age 2-4 years.

We performed nested case-control studies within ongoing birth cohort studies in Germany, The Netherlands, and Sweden and selected approximately 180 sensitized and 180 non-sensitized children per country. We measured levels of bacterial endotoxin, (13)glucans, and fungal extracellular polysaccharides (EPS) in dust samples from the children's mattresses and the living room floors.

Combined across countries, higher amounts of mattress dust and higher mattress dust loads of endotoxin, (13)-glucans, and EPS were associated with a significantly decreased risk of sensitization to inhalant allergens. After mutual adjustment, only the protective effect of the amount of mattress dust remained significant [odds ratio(95% confidence interval) 0.57(0.39-0.84)].

Higher amounts of mattress dust may decrease the risk of allergic sensitization to inhalant allergens. The effect might be partly attributable to endotoxin, (13)-glucans, and EPS, but could also reflect (additional) protective effects of (microbial) agents other than the ones measured. It is not possible to distinguish with certainty, which component relates to the effect, since their levels are highly correlated.

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