Urinary bladder cancer is caused by which species of schistosome -

Ans. is 'a' i.e., S. hematobium Schistosomes* These flukes (trematodes) reside in blood of venous plexus at different sites.* Three important species are:-i) S. haematobium : Veins of vesical & pelvic plexuses, less commonly in portal vein and its mesentric branch.ii) S. mansani: Mesentric veins draining sigmoido-rectal region (inferior mesentric veins).iii) S. Japonicum : Mesentric veins draining ilio-caecal region (superior mesentric vein).* Schistosomes are transmitted by Snails (Secondary host) to man (definitive host). Infective form in snail is cercaria.* Eggs of S. hematobium have terminal spine. Eggs of S.mansoni have lateral spine and eggs of S.japonicum have lateral knob.* S. hematobium causes bilharziasis (urinary schistosomiasis) which is characterized by painless terminal hematuria.* S. japonicum and S.mansoni cause Katayama fever. Rarerly, S. hematobium can also cause Katayama fever.* Fairly's test is an intradermal skin test with cercarial antigen. It is an allergic reaction, positive in all the varieties of schistosomiasis.* Schistosoma hematobium is a well known cause of urinary bladder cancer.