2014 John Wiley & Sons, Inc. Microsporidian infections have been described in a variety of domestic and wildlife mammalian hosts and less frequently in avian, amphibian, and reptilian hosts. The first reports in mammals identified Encephalitozoon cuniculi in rabbits and laboratory rodents in the early 1920s. That species remains the most frequently identified organism in a wide variety of nonhuman vertebrates. Several additional microsporidian species have been identified in various hosts including Encephalitozoon hellem, primarily identified in birds; Encephalitozoon intestinalis, typically regarded as a human enteric pathogen; and Enterocytozoon bieneusi. An increasing number of cases of naturally occurring microsporidiosis with two different species of microsporidia, E. cuniculi and E. bieneusi, are reported in nonhuman primates.
