ABSTRACT
During the last years, cryptosporidiosis has been recognized as an important cause of diarrheal disease. According to different references, water has been an important vehicle responsible for the transmission in many epidemic outbreaks. The high number of oocysts eliminated by human and animal hosts, as well as low infectious dose and its resistance to desinfectants are some factors which contribute to the infectious risk. It has been also pointed that bacteriologically acceptable water may contain parasites. In order to minimize such risks, it is desirable to protect the water supplies and to use multiple barriers (coagulation, sedimentation and filtration) in drinking water treatment. The aim of this work is to provide information about the different aspects conditioning the presence of Cryptosporidium in drinking water.