The intensity of nematode infections differed significantly between IL4 genotypes (Figure 2, Table 1): individuals of genotype T/T had higher parasite egg outputs than individuals of the more frequent genotypes C/T and C/C (t24,2 = 2.20, p CC-TT = 0.04, p CT-TT = 0.04). Here, IL4 is linked to Nematoda infectious disease.