Fig. 1.

The ‘acute versus chronic’ geohelminth infection paradigm as an environmental determinant of atopy. The Figure shows the relationship between the prevalence of atopy (defined by allergen skin test reactivity) and geohelminth infections in areas of different intensities of geohelminth transmission. Areas of low-level exposure are associated with a low prevalence of geohelminth infections, a predominantly acute geohelminth infection phenotype, and enhanced atopic reactivity while areas of high-level exposure are associated with a high prevalence of infections, a chronic infection phenotype, and suppressed atopic reactivity. The mechanisms by which acute and chronic geohelminth infections may affect atopic reactivity are shown in italics [93], MCs, mastcells.