A prospective cross-sectional study in Mozambique demonstrated that HIV-infected patients with malaria exhibited significantly elevated levels of myeloperoxidase (MPO), an indicator of neutrophil activation, and sCD25, an indicator of T-cell activation, in comparison to both malaria patients without HIV infection and HIV-infected patients without malaria, indicating heightened activation of neutrophils and T-cells in those with co-infection. The gene discussed is MPO; the disease is malaria.