A recent study[14] has disclosed the importance of IL-33 during murine hookworm infection: in IL-33 gene knockout mice infected with N. brasiliensis, cellular production of the Th2-type cytokine IL-13 was lessened and eosinophil recruitment reduced, and accompanied by a delayed worm expulsion in these animals.In the present work, allergens of mite and fungus activated IL-33 in children, suggesting that such increase in IL-33 reflects an initial responsiveness which, in later life and after repeated parasite exposure, is attenuated by regulatory cytokines like IL-27. The gene discussed is IL33; the disease is ancylostomiasis.