Mammalian Microsporidiosis

Abstract

Abstract. The phylum Microspora contains a diverse group of single-celled, obligate intracellular protozoa sharing a unique organelle, the polar filament, and parasitizing a wide variety of invertebrate and vertebrate animals, including insects, fish, birds, and mammals. Encephalitozoon cuniculi is the classic microsporidial parasite of mammals, and encephalitozoonosis in rabbits and rodents has been and continues to be recognized as a confounding variable in animal-based biomedical research. Although contemporary research colonies are screened for infection with this parasite, E. cuniculi remains a cause of morbidity and mortality in pet and conventionally raised rabbits. In addition, E. cuniculi is a potential pathogen of immature domestic dogs and farm-raised foxes. The recent discovery and identification of Encephalitozoon intestinalis, Encephalitozoon hellem, and Enterocytozoon bieneusi, in addition to E. cuniculi, as opportunistic pathogens of humans have renewed interest in the Microspora. Veterinary pathologists, trained in the comparative anatomy of multiple animal species and infectious disease processes, are in a unique position to contribute to the diagnosis and knowledge of the pathogenesis of these parasitic diseases. This review article covers the life cycle, ultrastructure, and biology of mammalian microsporaidia and the clinical disease and lesions seen in laboratory and domestic animals, particularly as they relate to Encephalitozoon species. Human microsporidial disease and animal models of human infection are also addressed. Often thought of as rabbit pathogens of historical importance, E. cuniculi and the related mammalian microsporidia are emerging as significant opportunistic pathogens of immunocompromised individuals.

Protozoan predation, diversifying selection, and the evolution of antigenic diversity in Salmonella

“…The amoeba Vannella platypodia was found to infect multiple fishes (68), whereas members of the genus Neoparamoeba preferentially colonize gills (69). The Microsporidian Encephalitozoon cuniculi is a pathogen of domesticated rabbits and dogs, whereas Encephalitozoon intestinalis, Encephalitozoon hellem, and Encephalitozoon bieneusi are opportunistic pathogens of humans (70). Commensal protozoa also show differential distribution among hosts.…”

A case of equine abortion caused by Encephalitozoon sp.

“…However, the specificity of the test used was not ascertained. The small intestine, the respiratory tract and the placenta are the common primary sites of E. cuniculi infection (Wasson and Peper, 2000). The latter is supported by the three reported cases of equine abortion, where only the placenta and no fetal tissues were infected with E. cuniculi.…”

“…Of the approximately 1,200 microsporidial species identified, 15 are presently known to infect mammals and at least 13 of them also humans, mainly severely immunocompromised patients with AIDS (Didier et al, 2000;Wasson and Peper, 2000). Three species of the genus Encephalitozoon have been identified in mammals, all of them also as human pathogens: E. cuniculi, with a wide host range among mammals, has a worldwide distribution in domestic rabbits and is found in distinct geographic areas in carnivores and monkeys, E. hellem, which has been reported in a few cases in avian hosts in the USA and Indonesia, and E. intestinalis, which was diagnosed in the faeces of farm animals in Mexico and in gorillas in Africa (Mathis et al, 2005).…”

Frequency of Emerging Parasites in HIV/AIDS and Oncological Patients Stool by Coprological and Molecular Analysis

“…The Microspora genus is composed of a broad group of single-celled obligate intracellular protozoa that share a polar filament and are capable of infecting evolutionarilydistinct hosts, from insects and fish to birds and mammals [6].…”