The disease burden caused by poor water, sanitation and hygiene is significant. For instance, soil transmitted helminthes (hookworm, roundworm, ringworm) infest approximately two billion people. Shistosomiasis infects and debilitates 200 million people. Trachoma, a disease related to poor sanitation and hygiene which can cause blindness, infects five million people. However, the most serious health impact of poor WASH is diarrheal disease, particularly on children.