Bhlhe40−/− mice showed higher parasitemia and delayed clearance, due to increased IL‐10 production by CD4+ T cells and reduced IFN‐γ production in the liver. Bhlhe40 deficiency did not affect CD4+ T‐cell proliferation, Treg, or humoral responses. Blockade of IL‐10R restored parasite control. The gene discussed is BHLHE40; the disease is parasitic infectious disease.