Within this study, we demonstrate that in the absence of IL-17A, infected IL-17A-deficient C57BL/6 mice present significantly reduced worm burden on days 7 and 28 p.i., but longer individual worms compared to C57BL/6 wildtype (WT) controls on day 28 p.i. Overall, IL-17A−/− mice had reduced immune cell infiltration within the thoracic cavity (TC; the site of infection), especially reduced absolute cell numbers of CD4+ T cells, CD4+Foxp3+ Treg, CD4+Rorγt+pStat3+ and CD4+Rorγt+pStat3+ IL-17A+ Th17 cells. The gene discussed is CD4; the disease is infection.