In the case of H. polygyrus, Hepworth and colleagues (98) reported “negligible” MLN ILC2 numbers (0.2 × 105 cells) at day 6 of infection of C57BL/6 mice, requiring exogenous IL-25 treatment to boost the number of MLN ILC2 cells to reach levels observed during N. brasiliensis infection (H. polygyrus: 3 × 105 cells vs. N. brasiliensis: 5 × 105 at d5 p.i.)(99). The gene discussed is IL25; the disease is infection.