in 1851, Theodor Bilharz described a parasitic infection (bilharzia) that would later be termed schistosomiasis. Currently, 200 million people in 74 countries have this disease; 120 million of them have symptoms, and 20 million have severe illness.1 Schistosomiasis is caused by parasitic trematode worms (schistosomes) that reside in the abdominal veins of their vertebrate definitive hosts. The life cycle of the schistosome is depicted in Figure 1Figure 1Life Cycle of the Schistosome.. Schistosomiasis is 1 of the 10 tropical diseases especially targeted for control by the Special Program for Research and Training in Tropical Diseases of the United Nations Development Program, the World Bank, and the World Health Organization.4 The 54th World Health Assembly has set a goal of treating annually at least 75 percent of the school-age children who are infected with schistosomes and soil-transmitted helminths.5