This dichotomy between parasitemia control and pathology/survival most likely reflects the complex role T cells play in (i) sustaining the innate inflammatory environment needed for proper parasitemia control, (ii) the immunopathology associated with prolonged inflammation, and (iii) in case of CD4+ T cells, their role in helping a T cell dependent anti-trypanosome antibody response. This evidence concerns the gene CD4 and parasitic infectious disease.