Of four genotypes of Encephalitozoon cuniculi, E. cuniculi genotype II is considered to represent a parasite that occurs in many host species in a latent asymptomatic form, whereas E. cuniculi genotype III seems to be more aggressive, and infections caused by this strain can lead to the death of even immunocompetent hosts. Although albendazole has been considered suitable for treatment of Encephalitozoon species, its failure in control of E. cuniculi genotype III infection has been reported. This study determined the effect of a 100× recommended daily dose of albendazole on an Encephalitozoon cuniculi genotype III course of infection in immunocompetent and immunodeficient mice and compared the results with those from experiments performed with a lower dose of albendazole and E. cuniculi genotype II. The administration of the regular dose of abendazole during the acute phase of infection reduced the number of affected organs in all strains of mice and absolute counts of spores in screened organs. However, the effect on genotype III was minor. Surprisingly, no substantial effect was recorded after the use of a 100× dose of albendazole, with larger reductions seen only in the number of affected organs and absolute counts of spores in all strains of mice, implying variations in albendazole resistance between these Encephalitozoon cuniculi genotypes. These results imply that differences in the course of infection and the response to treatment depend not only on the immunological status of the host but also on the genotype causing the infection. Understanding how microsporidia survive in hosts despite targeted antimicrosporidial treatment could significantly contribute to research related to human health.

• Keywords
• Encephalitozoon cuniculi, albendazole, genotype III, microsporidiosis, tolerance, treatment,
• MeSH
• Albendazole administration & dosage   pharmacology   MeSH
• Antifungal Agents administration & dosage   pharmacology   MeSH
• CD4 Antigens genetics   MeSH
• CD8 Antigens genetics   MeSH
• Cell Line MeSH
• Chlorocebus aethiops MeSH
• Encephalitozoon cuniculi drug effects   genetics   isolation & purification   MeSH
• Encephalitozoonosis drug therapy   MeSH
• Genotype MeSH
• Immunocompromised Host immunology   MeSH
• Microbial Sensitivity Tests MeSH
• Disease Models, Animal MeSH
• Mice, Inbred BALB C MeSH
• Mice, Inbred C57BL MeSH
• Mice, Knockout MeSH
• Mice, SCID MeSH
• Mice MeSH
• Colony Count, Microbial MeSH
• Vero Cells MeSH
• Animals MeSH
• Check Tag
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Albendazole MeSH
• Antifungal Agents MeSH
• CD4 Antigens MeSH
• CD8 Antigens MeSH