CD4 and infection: Grouping the participants by infection status (non-infected vs. infected as defined by the presence or absence of schistosome eggs in urine) rather than infection intensity produced similar results, so that in the younger age group infected participants had more Treg as proportion of CD4+ T cells than non-infected (p = 0.05), while in the older age group infected people had fewer Treg compared to non-infected (p = 0.02; data not shown).