Enterocytozoon bieneusi

Enterocytozoon bieneusi is a microsporidium, related to Cryptomycota and fungi, which has been reported globally in a wide range of mammalian and avian hosts. It is responsible for over 90% of documented cases of human microsporidiosis and causes varying clinical symptoms, typically diarrhea and wasting. Infection begins with ingestion of spores in contaminated water and food. Spores deliver the infective sporoplasm into host enterocytes via the discharged polar tube. Meronts form and develop into multinucleated plasmodia, which undergo sporogony to form sporoblasts and then mature spores. Spores released from infected cells are shed with the stool. Sequence analysis of the ribosomal internal transcribed spacer (ITS) has identified over 500 genotypes, some of which are generalists of zoonotic importance and pose a threat to public health. Population genetic data uphold the zoonotic nature and host specificity of the parasite. Knowledge of its pathogenicity, immune responses, and expanded treatment options are urgently needed.