Immunologic and Molecular Characteristics of Encephalitozoon-Like Microsporidia Isolated from Humans and Rabbits Indicate That Encephalitozoon cuniculi Is a Zoonotic Parasite

Abstract

To assess the zoonotic potential of Encephalitozoon-like microsporidia, we isolated and cultivated spores from specimens of urine, respiratory secretions, and stool from six patients infected with human immunodeficiency virus and from nine rabbits. Because spores of Encephalitozoon-like species are indistinguishable by microscopy, we characterized the isolates by western blot analysis and by restriction enzyme analysis of the small subunit (SSU) rDNA after amplification by the polymerase chain reaction. We identified Septata intestinalis in one patient and Encephalitozoon hellem in two symptomatic patients. Encephalitozoon cuniculi was found in all rabbits and in three patients. One of these patients had clinical manifestations of infection with this parasite (severe interstitial pneumonitis). We observed abatement of symptoms and cessation of parasite excretion when these patients were treated with albendazole. Our findings suggest that E. cuniculi may be pathogenic in humans and that it is a zoonotic parasite.

Prevalence of antibodies to Encephalitozoon cuniculi in European hares (Lepus europaeus)

“…Humans may be infected by the ingestion of food and water contaminated with spores of this parasite, [1] but it is possible that there are other ways of infection. In humans, E. cuniculi may affect the nervous and respiratory system, digestive tract, kidneys, and also the endocrine and lymphatic systems [20,21] with diarrhoea, pneumonitis, urinary tract infection and systemic diseases described among immunodeficient patients [21,22]. The infection in a healthy population is mostly without clinical signs.…”

Immune response to infection

“…E. cuniculi was the first mammalian microsporidian successfully grown in vitro [10]. It infects epithelial and endothelial cells, fibroblasts, and macrophages in a variety of mammals, including rabbits, rodents, carnivores, monkeys and humans [4,11,12]. In an experimental model, normal mice infected with E. cuniculi usually express few clinical signs of disease [13].…”

“…Encephalitozoon cuniculi, which was previously observed in laboratory animals, is considered to be a zoonotic infection [4]. Complications due to E. cuniculi infection have been reported in immunocompromised patients [5].…”

Experimental infection of immunocompetent and immunodeficient mice with Encephalitozoon cuniculi

“…This microsporidian infects endothelial and epithelial cells, fibroblasts and predominantly macrophages in a variety of mammals. It has been found in humans as well (Zender et al 1989, Deplazes et al 1996. In immunocompetent mice infected with E. cuniculi, latent infection remains asymptomatic as long as parasite multiplication and host immune response are balanced (Gannon 1980, Niederkorn et al 1981.…”