Cryptosporidiosis is a socially dangerous opportunistic infection caused by a variety of Cryptosporidium genus species that
in fact has been considered until recently to be nonpathogenic to a human being. The transmission of this infection is by water route and the current technologies of water purification cannot eliminate Cryptosporidium oocysts from drinking water . Therefore, the important lines of the research are to study the immunological aspects of
Cryptosporidia interaction with human cells, the development of a pathology, and persistence of pathogen. The review analyzes factors providing the mobility of the pathogen, its attachment to the cell and intake. The inhibitory effect of a number of substances preventing the binding of sporozoites to the cell is described. It has been established that Cryptosporidia can control the apoptosis of host cells and affect different parameters of cell functional activity. Nitric oxide is an important factor of innate resistance to Cryptosporidia, while IFN-gamma has a dominant role in control of infection and protection is associated with the production of a number of cytokines mainly of Th1 type. It is noted that the loss of local immune reactions may cause severe sequels in patients with
immunodeficiencies. The importance of nonspecific T-cell defense and antiparasitic antibodies in the control of the infection is demonstrated. It is concluded that the studies that give a better insight into the systemic mechanisms of infection protection should be conducted. In this direction, it can be promising to develop a model of infection in the immunocompetent and immunocompromised host to study the the mechanisms of control of cryptosporidial dissemination in immunodeficiencies.