Enterocytozoon bieneusi [′entərəˌsaitə′ӡu:ən bıə′nəʊsı]

Figure

Figure. Spores of Enterocytozoon bieneusiin a fecal smear from a patient with intestinal microsporidiosis. Spores are small (≈1.5 µm × 0.5 µm) and egg-shaped (calcofluor-white stain, original magnification ×1,000)....

From the Greek énteron (intestine), kútos (vessel, cell), and zỗion (animal), and the surname Bieneus, in memory of the first infected patient whose case was reported in Haiti during 1985. Enterocytozoon bieneusi, a member of the wide-ranging phylum Microsporidia, is the only species of this genus known to infect humans. Microsporidia are unicellular intracellular parasites closely related to fungi, although the nature of the relationship is not clear (Figure).

E. bieneusi, a spore-forming, obligate intracellular eukaryote, was discovered during the HIV/AIDS pandemic and is the main species responsible for intestinal microsporidiosis, a lethal disease before widespread use of antiretroviral therapies. More than 500 genotypes are described, which are divided into different host-specific or zoonotic groups. This pathogen is an emerging issue in solid organ transplantation, especially in renal transplant recipients.