As HIV-1 infection is associated with reduced CD4+ cell counts, and as the human immunological status is known to influence schistosome-human reactions, we also tested if there was an association or correlation between the intensity of S.mansoni infection and the immunological status, as measured by CD4+ cell counts, in people co-infected with HIV-1 and S. mansoni. This evidence concerns the gene CD4 and HIV-1 infection.