Although wild-type C57BL/6 mice are chronically susceptible to this parasite, a lack of MyD88 signaling was found to render mice markedly more resistant to infection, with a lower H. polygyrus egg output seen at days 14 and 27 post infection (Fig. 1A, 1B), an indication of lower worm fitness, which correlates with stronger immune responsiveness (10). The gene discussed is MYD88; the disease is infection.