CD4 and schistosomiasis: Several studies in animal models of filariasis [33] and schistosomiasis [34], [35], demonstrated that Treg phenotype populations develop following infection, whilst in infection with the murine gastrointestinal nematode Heligmosomoides polygyrus[36], functional regulation by CD4+CD25+ T cells suppresses the bystander response to an allergic provocation.