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Quantity and diversity of environmental microbial exposure and development of asthma: a birth cohort study

A M Karvonen1, A Hyvärinen, H Rintala

  • 1Department of Environmental Health, National Institute for Health and Welfare, Kuopio, Finland.

Allergy
|June 17, 2014
PubMed

Insights

Early-life microbial exposure, measured by a combined score, predicts asthma risk better than individual markers. Higher microbial quantity showed an inverted-U relationship with asthma incidence in children.

Area of Science:

  • Environmental microbiology
  • Pediatric allergy and immunology
  • Epidemiology

Background:

  • Early-life exposure to environmental microbes is linked to allergy development.
  • Characterizing microbial exposure is crucial for predicting respiratory symptoms and allergies.

Purpose of the Study:

  • To identify improved methods for assessing microbial exposure as a predictor of childhood allergies and respiratory issues.
  • To evaluate the association between microbial exposure markers and health outcomes in a birth cohort.

Main Methods:

  • A birth cohort of 410 children was followed until age 6.
  • Dust samples analyzed for microbial markers (endotoxin, muramic acid, ergosterol, qPCRs) at 2 months.
  • Asthma, wheezing, cough, atopic dermatitis, and specific IgEs assessed via questionnaires and serology.

Main Results:

  • A composite microbial exposure score (fungi, Gram-positive, Gram-negative bacteria) showed an inverted-U association with asthma incidence (P < 0.001).
  • Highest asthma risk was observed at medium microbial exposure levels, lowest at the highest levels.
  • Microbial diversity score was inversely associated with wheezing and associated with allergen sensitization.

Conclusions:

  • A score reflecting total microbial quantity is a better predictor of asthma than individual markers.
  • Microbial diversity and quantity are important factors in asthma development.
  • Further research is needed for better indicators of microbial exposure quantity and diversity.
Abstract

Keywords:
asthmaatopychildrenmicrobial exposurerespiratory tract disease

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