IL13 and schistosomiasis: Although a second functional polymorphism previously associated with schistosomiasis, rs20541 ((IL13R130Q)), was not associated with risk in this sample, the IL13 haplotype rs1800925T-rs20541A and rs1800925T-rs20541G were associated with a greater risk of progressing into late-stage schistosomiasis among patients infected with S. japonicum. In addition, rs1800925C-rs20541A appears to be protective from chronic infection and the development of late-stage schistosomiasis.