These are small, single-celled, obligately intracellular parasites linked to water sources as well as wild, and domestic animals.

At least 15 microsporidian species have been recognized[5] as human pathogens, spread across nine genera: The primary causes are Enterocytozoon bieneusi and Encephalitozoon intestinalis.

[citation needed] Diagnosis with Microsporidia can be done through gram-positive, acid-fast spores in stool and biopsy material with morphologic demonstration of the organism.

Initial detection through light microscopic examination of tissue sections, stools, duodenal aspirates, nasal discharges, bronchoalveolar lavage fluids, and conjunctival smears.

[7] Definitive diagnosis can also be achieved through fluorescein-tagged antibody immunofluorescence or electron microscopy,[7] and species identification can be done through PCR.