iNOS positive expression was identified in 44/50 (88%) of tissues with positive Schistosoma ova (P <0.00001) of which 28/44 (63.6%), 6/44 (13.7%) and 10/44 (22.7%) were found in SCC, TCC and cystitis, respectively (Additional file 1 see colored plate (2,3). This evidence concerns the gene NOS2 and chronic cystitis.