Studies on bronchial hyperreactivity, allergic responsiveness, and asthma in rural and urban children of the highlands of Papua New Guinea.

The prevalence of asthma and allergic responsiveness in rural and urban children of the highlands of Papua New Guinea was studied. Bronchial provocation studies with histamine demonstrated significant bronchial hyperreactivity in 0.5% (1 in 195) rural and 1.7% (1 in 59) urban children, rates which were significantly lower than those observed in corresponding adult populations (7%). Urban children demonstrated a higher incidence of skin test reactivity toward Dermatophagoides pteronyssinus, Aspergillus fumigatus, and dog dander than did the rural children. However, there were no significant differences between these populations with regard to total serum IgE levels, the degree of parasitism as judged by stool examination, or allergic responses to Ascaris suum, plantain, and coffee bean husk. A more detailed study demonstrated age- and sex-related differences in total IgE and mite-specific RAST scores in the rural but not the urban population. These data suggest an active suppression of the capacity of children to mount an IgE response to environmental allergens such as the mite manifesting itself as low asthma prevalence. The data also indicate that, although the underlying defect of bronchial hyperreactivity in asthma may be genetically inherited, it is not revealed until the lung has received an allergen-induced inflammatory insult.