Schistosomiasis also termed snail fever or bilharzia is a disease caused by parasitic flatworms called schistosomes. Infection with Schistosoma mansoni, S. haematobium, and S. japonicum causes illness in humans; less commonly, S. mekongi and S. intercalatum can cause disease.
Pathogenicity is the capacity of a microorganism to cause disease in a host. Virulence refers to the intensity or degree of pathogenicity. The virulence varies among different microorganisms and also among strains of same species. Virulence factors are the structures, substances or properties which help a pathogen to cause infection. These factors help the microorganism