A HIGH-YIELD OUTBRED SUCKLING MOUSE MODEL OF CRYPTOSPORIDIOSIS

Outbred suckling mice (NMRI strain) were used as hosts. They were init ially inoculated with oocysts of human origin, and subsequently with p arasites recovered from the mouse ileal mucosa. Cryptosporidia were co unted in an aliquot of whole-ileum homogenate. Parasite load was expre ssed as cryptosporidia per centimeter of ileum. Serial passage of C. p arvum in NMRI mouse litters led to a gradual amplification of parasite burden relative to animals initially inoculated with the human isolat e.