ABSTRACT
Microsporidia is a diverse group of obligate intracellular parasites that includes more than 1200 named species.1 Microsporidia has a wide range of vertebrates and invertebrate as hosts; most of the species infect invertebrates and sh, but at least 14 species in 8 genera infect humans.2 The most common microsporidian species infecting humans are Enterocytozoon bieneusi, Encephalitozoon cuniculi, Encephalitozoon intestinalis, and Encephalitozoon hellem. Of these four species, E. bieneusi is the most frequently diagnosed species in humans worldwide, mainly associated with chronic diarrhea and wasting syndrome.3,4 It has been recognized as an opportunistic pathogen of immunocompromised patients (HIV-infected people or organ transplant recipients),5-10 but immunocompetent individuals have also been found infected.11-16 In addition, E. bieneusi has been identied in a variety of wild, farm, and companion mammals, raising the question on the importance of animal reservoirs in the epidemiology of this parasite.17 E. bieneusi has been detected in retail fresh food produce (raspberries, sprouts, and lettuce)18 in Poland and has been found to be the cause of a large foodborne outbreak in Sweden.19 The identication of spores of E. bieneusi in water supplies suggests that water can be a potential vehicle in the transmission of this parasite not only for humans but also for animals.20 Identication of microsporidia in water sources has led to their inclusion on the National Institute of Allergy and Infectious Diseases Category B Priority List of biodefense pathogens (https://www.niaid.nih.gov/topics/BiodefenseRelated/Biodefense/Pages/CatA.aspx) and in the Environmental Protection Agency drinking water Contaminant Candidate List of concern for waterborne transmission (https://water.epa.gov/scitech/drinkingwater/dws/ccl/ccl2.cfm).
