Background Through its powerful immunoregulatory effects, infection with atypical mycobacteria may exert a protective effect on the development of childhood allergic disease.
Objective To examine the relationship between childhood atopy or allergic disease and previous infection with four species of atypical mycobacteria.
Methods Eight hundred and six children aged 8–18 years and living in rural Crete – most of whom had had previous BCG immunization – underwent skin prick testing with 10 aeroallergens; their parents completed a standardized questionnaire relating to allergic disease. No less than 8 weeks later each child underwent intradermal skin tests with 0.1 mL solutions of four selected mycobacterial reagents (Aviumin C, Gordonin, Chelonin and Ranin I).
Results Twenty-three percent of children were atopic on skin prick testing; far fewer had symptoms of asthma (5%) or hayfever in conjunction with a positive prick test to pollens (2%). Eighty percent of children had positive skin responses to one or more mycobacterial species. Among all children – and those with a BCG scar – there was no association between atopy or allergic symptoms and mycobacterial skin responses; among the few children without a BCG scar however those with positive mycobacterial responses were less likely to be atopic or to report allergic symptoms; these differences were not statistically significant.
Conclusions Our findings, in a population of BCG-immunized children, do not lend support to the suggestion that infection with atypical mycobacteria is protective against childhood allergic disease.