In Vitro Replication of Nosema algerae (Microsporidia), a Parasite of Anopheline Mosquitoes, in Human Cells above 36° C

Microsporidia form a large and ubiquitous group of obligately intracellular parasitic eukaryotes, increasingly recognized as pathogens in humans. Transmission of invertebrate microsporidia to mammals has been considered impossible because temperature seemed to be a limiting factor for development. Nosema algerae, a microsporidian of anopheline mosquitoes, was cultured in human muscle fibroblasts at temperatures of 31° C and 38° C. This is the first record of an invertebrate microsporidian developing in human cells at a temperature above 36° C. The ultrastructure of N. algerue growing in human muscle fibroblasts is similar to that of Bruchiola vesicularum, a microsporidian species previously described in the muscle of an AIDS patient.