Individuals with evidence of past HP infection but who no longer had ongoing infection (group P) exhibited elevated frequencies of CD3+CD8−CCR6+IL-17A+ cells in the blood (median 1.4%, range 0.3–4.9%) that was statistically different from individuals who were naive to HP (group N, median 0.8%, range 0.1–2.8%) (figure 1B). The gene discussed is IL17A; the disease is infection.