[Epidemiological importance of soil and water reservoirs in the natural foci of cryptosporidiosis].

The main penetration route of cryptosporidia oocysts (at the infective stage) from animal carriers in the natural ecosystems of the forest zone into the environment of human habitat has been newly established. Oocysts excreted with feces are concentrated in the surface layer of the soil, then washed into water reservoirs. The viability of oocyts from the soil and the silt of river sand banks and shallows has been experimentally shown. As a result, the natural foci of cryptosporidiosis have been found to play an important role in the supply of infective agents to rivers serving as sources of water supply. From epidemiological viewpoint natural ecosystems are comparable with cattle-breeding farms and pastures. Humans run a real risk of being infected during visits to a forest.