Microsporidia have been recently recognized as opportunistic pathogens in AIDS patients. In attempt to develop an animal model with features similar to the infections observed in the immunodeficient patients, the adult severe combined immunodeficient mice (SCID) were administered both intraperitoneally and perorally by 2 x 10(7) spores of the murine isolate of E. cuniculi. The experimental inoculation caused a severe, fatal disease characterized by the dissemination of microsporidia into the host tissues. The dominant route of E. cuniculi dissemination in the SCID mice was continual direct extension from the site of inoculation to adjacent tissues and organs, terminating in hematogenous spread of infection in the host. The different courses of microsporidiosis in SCID mice relative to the mode of inoculation (i.p. vs. p.o.) was observed. The survival time of i.p. infected SCID mice was 3 weeks--vs. 5 weeks in p.o. infected SCID mice. Experimental microsporidiosis in SCID mice should provide a useful model for studies in microsporidial pathogenesis, mechanisms of resistance, immunotherapy, and in evaluating potential antimicrosporidial agents.

Institute of Parasitology Academy of Sciences of the Czech Republic Ceské Budĕjovice

Latent microsporidiosis caused by Encephalitozoon cuniculi in immunocompetent hosts: a murine model demonstrating the ineffectiveness of the immune system and treatment with albendazole