The observed decline in Treg frequencies with increasing prior malaria incidence contrasts with that of another regulatory T lymphocyte population, IL10-producing Th1 cells, which we have recently shown to dominate the P. falciparum-specific CD4 T cell response among heavily malaria-exposed children, including among children from both the TCC and the PRISM Nagongera, Tororo cohorts tested here [22,56]. The gene discussed is IL10; the disease is malaria.