Three main species of Schistosomiasis affect humans.
Infection can occur when skin comes in contact with contaminated fresh water in which certain types of snails, that carry schistosomes, are living.
Persons who come in contact with fresh or contaminated water from canals, rivers, streams, or lakes, are at higher risk of developing this disease. The parasite penetrates the skin. Within several weeks, the worm grows inside the blood vessels of the body and produce eggs (CDC, 2005).
According to the World Health Organization, mortality due to schistosomiasis is estimated at 11,000 deaths per year and the burden of disease at 1.7 million (WHO, 2001). This would place schistosomiasis as the third most important disease.