EN
Suckling mice and immunosuppressed adult mice were used as model hosts to compare the endogenous development of two isolates of C. parvum obtained from naturally infected calves in different seasons of the year. There were no differences in these two isolates as to their location, time of appearance, intensity of infection and antigenicity. Present study indicates that Cryptosporidium infection may be easily established in 5-7 day old outbred Swiss mice. The peak of infection is shown on day 8 after inoculation and shortly after that a self-limiting process of infection takes place. However, C. parvum does not develop endogenously in adult immunosuppressed mice. The lack of establishment of infection in these animals, even in latent state, indicates that age dependent mechanisms of immunity, developed in mice, are not impaired by prednisolone or cyclophosphamide.There was no difference in biological characteristics of two isolates C. parvum. Moreover, the present study illustrates that oocysts, spread by naturally infected calves in autumn and winter, are infective for suckling mice, which might be associated in transmissibility of C. parvum.