Microsporidiosis: An emerging and opportunistic infection in humans and animals
Introduction
Microsporidia were first identified as the cause of pébrine disease of silkworms in 1857 (Nägeli, 1857). Since then, over 1200 species of microsporidia have been identified as causes of infection in a wide range of invertebrate and vertebrate hosts (Wittner, 1999). Microsporidia were only sporadically identified in humans prior to 1985 and then emerged as causes of opportunistic infections associated with diarrhea and systemic disease in persons with AIDS. As diagnostic methods improved and awareness increased, microsporidiosis also is being detected in organ transplant recipients, children, travelers, contact lens wearers, and the elderly (Bryan and Schwartz, 1999, Schwartz and Bryan, 1999, Deplazes et al., 2000, Didier et al., 2004).
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Organism
Microsporidia are nucleated, single-celled, obligately intracellular parasites that were considered to be early-branching eukaryotic organisms based on the presence of prokaryote-like ribosomes, and the apparent absence of true Golgi, peroxisomes, and mitochondria (Vossbrinck et al., 1987, Vavra and Larsson, 1999, Desportes-Livage, 2000). The microsporidia, however, were recently reclassified with the fungi based on observations that include the presence of chitin in the spore wall,
Disease associated with infection
Clinical symptoms and disease associated with microsporidiosis vary with the species causing the infection and the status of the host's immune system. E. bieneusi infections are believed to result most commonly through ingestion of spores with the primary site of infection developing in the epithelial cells (enterocytes) lining the duodenum and jejunum of the small intestine (Fig. 1). Persistent diarrhea, abdominal pain, and weight loss are common clinical symptoms associated with E. bieneusi
Laboratory diagnosis
Serological methods such as immunofluorescent antibody staining, ELISA, and western blot assay have been useful for diagnosing microsporidiosis in immunologically competent laboratory animals such as rodents, rabbits, and carnivores. E. cuniculi is probably the most common microsporidian identified in laboratory animals, and these serological assays relied upon the availability of E. cuniculi organisms that could be grown in culture for generating the required antigens since 1969 (Shadduck, 1969
Epidemiology
Criteria used to characterize a pathogen as a cause of emerging infectious diseases are that a pathogen recently appeared in humans or animals, rapidly increased in incidence, expanded in geographic range, or developed increased or novel mechanisms of resistance (Institute of Medicine and Report, 1992; http://www.iom.edu/report.asp?id=4572). In this context, microsporidia are considered etiologic agents of emerging infectious disease based on the relatively recent discovery of new species of
Therapy and prevention strategies
The two most frequently administered drugs for treating microsporidiosis in animals and humans include albendazole and fumagillin (Conteas et al., 2000, Gross, 2003). Albendazole is a benzimidazole that inhibits tubulin polymerization and also has been used as an anthelmintic and anti-fungal agent. This drug is effective against Encephalitozoon species of microsporidia that infect mammals (including humans), but is only variably effective against E. bieneusi (Kotler and Orenstein, 1999, Conteas
Conclusions
Interest in the microsporidia has grown tremendously during the last 20 years with the recognition of new species that cause opportunistic infections in AIDS patients. New information about the relationship between microsporidia and other organisms led to a change in classification of microsporidia from the protozoa to the fungi, and continued studies on the molecular phylogeny of the microsporidia are likely to identify new drug targets for developing more effective therapeutic strategies. As
Acknowledgments
This work was presented at the Seventh Annual Conference on New and Re-emerging Infectious Diseases, April 15–16, 2004 in Urbana, IL and was funded through grants RR00164 and AI39968 from the National Institutes of Health.
References (180)
- et al.
Evidence for the smallest nuclear genome (2.9 Mb) in the microsporidium Encephalitiozoon cuniculi
Mol. Biochem. Parasitol.
(1995) - et al.
Treatment of HIV-1-associated microsporidiosis and cryptosporidiosis with combination antiretroviral therapy
Lancet
(1998) - et al.
Microsporidial keratoconjunctivitis in healthy individuals: a case series
Ophthalmology
(2003) - et al.
Corneal microsporidiosis. A case report including ultrastructural observations
Ophthalmology
(1990) - et al.
Biology of microsporidian species infecting mammals
Adv. Parasitol.
(1998) - et al.
Microsporidiosis in mammals
Microbes Infect.
(2000) - et al.
Detection of microsporidia in surface water: a one-year follow-up study
FEMS Immunol. Med. Microbiol.
(2000) - et al.
Detection of microsporidia, cryptosporidia and giardia in swimming pools: a one-year prospective study
FEMS Immunol. Med. Microbiol.
(2002) - et al.
Cryptosporidia and microsporidia–waterborne diseases in the immunocompromised host
Diagn. Microbiol. Infect. Dis.
(1999) - et al.
Evidence for loss of mitochondria in microsporidia from a mitochondrial- type HSP70 in Nosema locustae
Mol. Biochem. Parasitol.
(1997)
A mitochondrial Hsp70 orthologue in Vairimorpha necatrix: molecular evidence that microsporidia once contained mitochondria
Curr. Biol.
Clinical syndromes associated with microsporidiosis
Adv. Parasitol.
Fox encephalitozoonosis: isolation of the agent from an outbreak in farmed blue foxes (Alopex lagopus) in Finland and some hitherto unreported pathologic lesions
J. Vet. Med. B. Infect. Dis. Vet. Publ. Health
Encephalitozoonosis (nosematosis) of the cornea
Br. J. Ophthalmol.
The isolation of microsporidia and other pathogens from concentrated ditch water
J. Am. Mosq. Control Assoc.
Chemotherapy of microsporidiosis: benzimidazoles, fumagillin, and polyamine analogues
Novel synthetic polyamines are effective in the treatment of experimental microsporidiosis, an opportunistic AIDS-associated infection
Antimicrob. Agent Chemother.
Antibody against Encephalitozoon cuniculi in Swedish homosexual men
Scand. J. Infect. Dis.
Diagnosis of encephalitozoonosis in man by serological tests
Br. Med. J.
Molecular karyotype diversity in the microsporidian Encephalitozoon cuniculi
Parasitology
Microsporidia: a new sexually transmissable cause of urethritis
Genitourin. Med.
Encephalitozoon hellem in budgerigars (Melopsittacus undulatus)
Vet. Pathol.
Comparison of assays for antibodies to Encephalitozoon cuniculi in rabbits
Lab. Anim.
Immunologic, microscopic, and molecular evidence of Encephalitozoon intestinalis (Septata intestinalis) infection in mammals other than humans
J. Infect. Dis.
Epidemiology of microsporidiosis
Microsporidia: opportunistic pathogens in patients with AIDS
Prog. Clin. Parasitol.
Prevalence of Enterocytozoon bieneusi in swine: an 18-month survey at a slaughterhouse in Massachusetts
Appl. Environ. Microbiol.
The eradication of Encephalitozoon cuniculi from a specific pathogen-free rabbit colony
Lab. Anim. Sci.
Developmental morphology and life cycles of the microsporidia
Ultrastructure and development of Pleistophora ronneafiei n.sp., a microsporidium (Protista) in the skeletal muscle of an immune-compromised individual
J. Eukaryot. Microbiol.
A comparison of two microsporidian parasites in enterocytes of AIDS patients with chronic diarrhea
J. Protozool.
Corneal microsporidioses: characterization and identification
J. Protozool.
Septata intestinalis n.g., n.sp., an intestinal microsporidian associated with chronic diarrhea and dissemination in AIDS patients
J. Eukaryot. Microbiol.
Identification of a new Nosema-like microsporidian associated with myositis in an AIDS patient
J. Eukaryot. Microbiol.
Brachiola vesicularum, n.g., n.sp., a new microsporidium associated with AIDS and myositis
J. Eukaryot. Microbiol.
The Microsporidia of Vertebrates
Phylum microsporidia
Microsporidiosis in a Gouldian finch (Erythrura [Chloebia] gouldiae)
Aust. Vet. J.
A revised six-kingdom system of life
Biol. Rev. Camb. Phil. Soc.
Serological differentiation of microsporidia with special reference to Trachipleistophora hominis
Parasite
Intestinal parasitic infections among human immunodeficiency virus-infected and-uninfected children hospitalized with diarrhea in Bangkok
Thailand SE Asian J. Trop. Med. Publ. Health
Encephalitozoon cuniculi—clinical and epidemiologic significance. Results of a preliminary serologic study in humans
Epidemiol. Mikrobiol. Imunol.
Prevalence of antibodies to Encephalitozoon cuniculi (microsporidia) in angora goats—a potential risk of infection for breeders
Ann. Agric. Environ. Med.
Therapy for human gastrointestinal microsporidiosis
Am. J. Trop. Med. Hyg.
Urethritis associated with disseminated microsporidiosis: clinical response to albendazole
Clin. Infect. Dis.
Waterborne outbreak of intestinal microsporidiosis in persons with and without human immunodeficiency virus infection
J. Infect. Dis.
TNP-470 is an effective antimicrosporidial agent
J. Infect. Dis.
Fatal myositis due to the microsporidian Brachiola algerae, a mosquito pathogen
N. Engl. J. Med.
Emerging pathogens: isospora, cyclospora and microsporidia
Parasitology
Microsporidiosis and HIV
J. Acquir. Immune Defic. Syndr.
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