Clinical & Experimental Allergy

House dust mite allergen exposure in infancy

Authors


Dr Tovey Department of Medicine, Blackburn Building D06, University of Sydney, Sydney, NSW 2006, Australia.

Abstract

Background

Infancy may be a critical time for exposure to house dust mite allergens, when exposure to high levels can increase the risk of allergic sensitization and the development of asthma in later life.

Objective

To measure house dust mite allergen (Der p 1) concentration in the infants' environment and examine lifestyle factors which may influence mite allergen exposure.

Methods

Infants aged between 4 and 12 months (n = 134) from the western region of Sydney, Australia, participated. Reservoir dust samples were collected from four sites within each home: infant's bed, second bed (adult or second child's bed), lounge floor and sheepskins (where available). Settling aeroallergen was collected for 10–14 d in Petri dishes in the infant's room. Der p 1 was measured by ELISA. A questionnaire on types of bedding, sleeping and playing patterns of the infant was completed by the parents at the time of dust collection.

Results

All infants were exposed to at least one site with Der p 1 concentrations greater than 10 μg/g fine dust. The mean settling aeroallergen level in the infants' room was 24 ng Der p 1/m2day and this was weakly related to bed allergen levels (= 0.21, < 0.05). Mattress type had a weak effect on Der p 1 levels as measured in the whole bed (= 0.07), while bed cover and bed type had no effect (> 0.6). The mean product of time spent at a site and its allergen concentration was highest for beds in 69% of infants.

Conclusion

The high level of allergen exposure in the environment of this group of infants places them at an increased risk of early sensitization and development of asthma. Any strategy to reduce asthma prevalence should address these high and avoidable levels.

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