Role of allergens in the natural history of childhood asthma.
This review article deals with the role of allergens in the natural history of asthma. Several studies clearly demonstrate a strong relationship between allergen exposure, especially mite-allergen exposure, and risk of sensitization. Those studies have led to the proposed threshold equal to 2 micrograms/g dust. However, more recent evidence shows that there is no threshold for sensitization, especially in children born to atopic parents. As far as occurrence of asthma is concerned, geographical comparisons of asthma prevalence across Europe, Australia or in other populations with contrasted exposure to mite allergens do show such a relationship. The latter is not exemplified in studies performed within the same geographical area, probably because the exposure categories are not contrasted enough. Finally, asthma severity in mite sensitive asthmatics is partly modulated by allergen exposure but repeated exposure to low amounts of allergen can trigger disease activity. In conclusion, allergen exposure is involved at each step of the natural history of asthma. Even low doses can play a significant role. Thus avoidance methods, in order to be efficient in primary and secondary prevention, should lead to a drastic decrease in allergenic exposure.
Charpin
D
D
Service de Pneumologie allergologie, Hôpital Nord Marseille et UPRES 2050, France.
Dutau
H
H
D000485:Allergens; D001249:Asthma / Q000503:physiopathology*; D002648:Child; D006801:Humans
D000485:Allergens