Sex as a biological variable in HIV-1 and schistosome co-infection

The sex of people living with HIV-1 infection, schistosome infection, or both, is a fundamental determinant of their clinical outcomes and of how these two infections interact in the host. Data from longitudinal and cross-sectional human studies and animal models indicate that males with HIV-1 and schistosome co-infection excrete fewer schistosome eggs and might have higher HIV-1 RNA viral loads and greater liver damage. Females with schistosome infection appear to have higher risk of HIV-1 acquisition than females without, particularly in Schistosoma haematobium infection, and a greater risk of death in HIV-1 and schistosome co-infection. Greater transmission of HIV-1 to partners has been shown in both sexes in those with schistosome infection. Biological sex is a consequential factor affecting pathophysiological and clinical responses in HIV-1 and schistosome co-infection. Designing future analyses to incorporate sex is vital to optimise research and care for people living with HIV-1, schistosomes, and HIV-1 and schistosome co-infection.