IL17A and infection: Although IL-17 has been considered an important player in the mediation of hostprotection against extracellular and some intracellular pathogens, the role of IL-17in host defense against intracellular protozoan parasites remains less well studied.Infection studies demonstrate that Th17 cells mediate host defense againstTrypanosoma cruzi105, Toxoplasma gondii106, Leishmania braziliensis107, and Echinococcus granulosus108 infections.