IGHG3 and schistosomiasis: Finally, even though cross-reactivity between Plasmodium and S. mansoni infections is known to occur [9,10], SWA-IgG4 levels, which have been shown to correlate with schistosome infection intensities in many settings [27-32], were only weakly correlated with the Pfs-IgG3 levels and were raised in a different part of the study area to Pfs-IgG3, indicating that the approach was not influenced by the presence of schistosomiasis.