Schistosomiasis Transmitted (image) Smithsonian Caption Schistosomiasis is transmitted when parasitic eggs excreted by diseased individuals hatch in water and infect Bulinus nyassanus snails, the intermediate host that releases larval flatworms capable of penetrating human skin in aquatic environments. National Museum of Natural History scientist Bert Van Bocxlaer and an international team of researchers revealed that anthropogenic changes in Africa's Lake Malaŵi are a driving force behind the increase of schistosomiasis, a debilitating tropical disease caused by parasitic flatworms that affects 250 million people worldwide and threatens 600 million more. Credit Modified from Stauffer et al. (1997), BioScience 47 (1): 41-49 with permission. Usage Restrictions None Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.