EN
The congenital or acquired cause the state of immune deficiency. To acquired factors belong immunosuppressive therapy after grafting and in systemie diseases as infections with HIV. There is a number of parasitic organisms, mainly protozoa, which preferentially settle in immunocompromised persons. The opportunistic parasites are present in the nearest environment. Some of them were newly recognized as human invaders. The state of immune deficiency may reactivate latent infections, that occurs with Toxoplasma gondii infection. Some parasitic infections which are benign and self - resolving, when affecting immunocompetent hosts, become fulminant or disseminated and very often life - threatening in immunosuppressed individuals.