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Sharma S, Das S, Joseph J, Vemuganti GK, Murthy S. Microsporidial Keratitis: Need for Increased Awareness. Surv Ophthalmol 2011; 56:1-22. [DOI: 10.1016/j.survophthal.2010.03.006] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2009] [Revised: 03/24/2010] [Accepted: 03/30/2010] [Indexed: 12/24/2022]
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Abstract
Microsporidia are long-known parasitic organisms of almost every animal group, including invertebrates and vertebrates. Microsporidia emerged as important opportunistic pathogens in humans when AIDS became pandemic and, more recently, have also increasingly been detected in otherwise immunocompromised patients, including organ transplant recipients, and in immunocompetent persons with corneal infection or diarrhea. Two species causing rare infections in humans, Encephalitozoon cuniculi and Brachiola vesicularum, had previously been described from animal hosts (vertebrates and insects, respectively). However, several new microsporidial species, including Enterocytozoon bieneusi, the most prevalent human microsporidian causing human immunodeficiency virus-associated diarrhea, have been discovered in humans, raising the question of their natural origin. Vertebrate hosts are now identified for all four major microsporidial species infecting humans (E. bieneusi and the three Encephalitozoon spp.), implying a zoonotic nature of these parasites. Molecular studies have identified phenotypic and/or genetic variability within these species, indicating that they are not uniform, and have allowed the question of their zoonotic potential to be addressed. The focus of this review is the zoonotic potential of the various microsporidia and a brief update on other microsporidia which have no known host or an invertebrate host and which cause rare infections in humans.
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Affiliation(s)
- Alexander Mathis
- Institute of Parasitology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.
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Rauz S, Tuft S, Dart JKG, Bonshek R, Luthert P, Curry A. Ultrastructural examination of two cases of stromal microsporidial keratitis. J Med Microbiol 2004; 53:775-781. [PMID: 15272065 DOI: 10.1099/jmm.0.45524-0] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Two cases with chronic stromal keratitis are described in immunocompetent hosts where the diagnosis was originally thought to be herpetic or adenoviral disease. Light microscopy and ultrastructural examination of corneal tissue by electron microscopy were performed following penetrating keratoplasty (case 1) and corneal biopsy (case 2). Specimens from both cases were analysed for viral identification by PCR. Two different species of Microsporidia were identified. Case 1 represents the fourth reported case of corneal stromal Vittaforma corneae where the spores measured 3.3 x 1.4 microm, arranged in characteristic linear groups of about four to eight. Each spore contained a diplokaryotic nucleus and a single row of ten polar tube coils. By contrast, case 2 is the first reported case of stromal keratitis caused by Trachipleistophora hominis. In this case, spores measured 4 x 2.4 microm, located typically within packets. In this species, the polar tube was arranged as a single row of about 10-13 profiles. Viral DNA could not be amplified by PCR. In conclusion, microsporidial stromal keratitis should be considered in culture-negative cases refractory to medical therapy. As microbiological culture techniques are unsuccessful, diagnosis may only be established following histopathological and ultrastructural examination of corneal tissue.
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Affiliation(s)
- Saaeha Rauz
- Corneal and External Diseases Service, Moorfields Eye Hospital NHS Trust, City Road, London EC1V 2PD, UK 2,3Department of Histopathology2 and Health Protection Agency3, Manchester Royal Infirmary, Oxford Road, Manchester M13 9WZ, UK
| | - Stephen Tuft
- Corneal and External Diseases Service, Moorfields Eye Hospital NHS Trust, City Road, London EC1V 2PD, UK 2,3Department of Histopathology2 and Health Protection Agency3, Manchester Royal Infirmary, Oxford Road, Manchester M13 9WZ, UK
| | - John K G Dart
- Corneal and External Diseases Service, Moorfields Eye Hospital NHS Trust, City Road, London EC1V 2PD, UK 2,3Department of Histopathology2 and Health Protection Agency3, Manchester Royal Infirmary, Oxford Road, Manchester M13 9WZ, UK
| | - Richard Bonshek
- Corneal and External Diseases Service, Moorfields Eye Hospital NHS Trust, City Road, London EC1V 2PD, UK 2,3Department of Histopathology2 and Health Protection Agency3, Manchester Royal Infirmary, Oxford Road, Manchester M13 9WZ, UK
| | - Philip Luthert
- Corneal and External Diseases Service, Moorfields Eye Hospital NHS Trust, City Road, London EC1V 2PD, UK 2,3Department of Histopathology2 and Health Protection Agency3, Manchester Royal Infirmary, Oxford Road, Manchester M13 9WZ, UK
| | - Alan Curry
- Corneal and External Diseases Service, Moorfields Eye Hospital NHS Trust, City Road, London EC1V 2PD, UK 2,3Department of Histopathology2 and Health Protection Agency3, Manchester Royal Infirmary, Oxford Road, Manchester M13 9WZ, UK
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Bontems F, le Floch P, Duffieux F, Biderre C, Peyret P, Lallemand JY. Homology modeling and calculation of the cobalt cluster charges of the Encephazlitozoon cuniculi methionine aminopeptidase, a potential target for drug design. Biophys Chem 2003; 105:29-43. [PMID: 12932577 DOI: 10.1016/s0301-4622(03)00056-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Fumagillin is a potent anti-angiogenic drug used in cancer treatments. It is also one of the few molecules active against the Enterocytozoon and Encephalitozoon parasites responsible for various clinical syndromes in HIV-infected or immunosuppressive treated patients. Its toxicity, however, makes desirable the design of more specific molecules. The fumagillin target, as anti-angiogenic agent, is the methionine aminopeptidase, an ubiquitous metallo-enzyme responsible for the removing of the N-terminal methionine in nascent proteins. By analogy, it has been proposed that this enzyme could also be the target in the parasites. As a first approach to verify this and to determine if it would be possible to design a more specific derivative, we have built a homology model of the E. cuniculi aminopeptidase. The charges of the two cobalt ions present in the active site and of the side-chains involved in their binding were computed using ab-initio methods. A preliminary comparison of the interactions of the fumagillin and of a related compound, the TNP-470, with both the human and the parasitic enzymes strongly support the hypothesis that the parasitic aminopeptidase is indeed the target of the fumagillin. It also suggests that the TNP-470 interact identically with both enzymes while there could be small differences in case of the fumagillin.
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Abstract
The results of a serological test for Encephalitozoon cuniculi in 125 pet rabbits are reviewed, together with follow-up studies of clinical cases. Blood samples were taken from 38 asymptomatic rabbits and 87 rabbits showing neurological, renal or ocular signs suggestive of encephalitozoonosis. In the asymptomatic group, six of 26 (23 per cent) apparently healthy rabbits, sampled as part of a health screen, were seropositive; of the remaining 12 asymptomatic rabbits, sampled because they lived with seropositive companions, eight (66 per cent) were seropositive. Fifty-eight of the rabbits with clinical disease showed neurological signs, including head tilt, seizures, ataxia and swaying; three of them also showed renal signs and two showed ocular signs, and these five rabbits were all seropositive. Head tilt was the most common neurological sign in 21 of 23 (91 per cent) of the seropositive cases. All nine rabbits with ocular lesions were seropositive. In follow-up studies of clinical cases, the rabbits showed variable responses to treatment with albendazole, fenbendazole, antibiotics or corticosteroids, and some cases recovered without treatment.
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Affiliation(s)
- F M Harcourt-Brown
- IDEXX Laboratories, Grange House, Sandbeck Way, Wetherly, West Yorkshire LS22 4DN
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Abstract
Microsporidia are ubiquitous organisms that are emerging pathogens in humans. These are most likely zoonotic and/or waterborne infections. In the immunosuppressed host, such as those treated with immunosuppressive drugs or infected with human immunodeficiency virus particularly at advanced stages of the disease, microsporidia can produce a wide range of clinical diseases. The most common manifestation is gastrointestinal tract infection; however, encephalitis, ocular infection, sinusitis, myositis and disseminated infection have also been described. In addition, these organisms have been reported in immune competent individuals. Multiple genera are involved in these infections and different organisms can result in distinct clinical pictures. Differences in clinical and parasitologic response to various therapeutic agents have emerged from clinical, as well as in vitro and in vivo studies. Currently there are no precisely defined guidelines for the optimal treatment of microsporidial infections. This article reviews the available data on compounds with in vitro activity and/or in vivo efficacy for microsporidial infections. Copyright 2000 Harcourt Publishers Ltd.
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Affiliation(s)
- Sylvia F. Costa
- Department of Medicine, Division of Infectious Diseases, Albert Einstein College of Medicine, Bronx, New York, USA
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Fournier S, Liguory O, Sarfati C, David-Ouaknine F, Derouin F, Decazes JM, Molina JM. Disseminated infection due to Encephalitozoon cuniculi in a patient with AIDS: case report and review. HIV Med 2000; 1:155-61. [PMID: 11737344 DOI: 10.1046/j.1468-1293.2000.00022.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE AND METHODS Infections due to microsporidia are increasingly recognized as opportunistic infections in patients with AIDS. We describe here a case of disseminated infection due to Encephalitozoon cuniculi and review the literature on this microsporidial infection. RESULTS All 12 patients reported in the literature had AIDS and nine presented with disseminated infection involving the kidneys, sinuses, lungs, brain and conjunctiva. Asymptomatic infection was seen in three patients. Microsporidia were detected by light microscopy examination of urine samples in all the cases. Species identification was performed by various genotypic methods or transmission electron microscopy. Eight of 12 patients who received albendazole therapy experienced clinical improvement with documented clearance of spores in five of these eight patients. Two patients relapsed. CONCLUSIONS E. cuniculi infection should be considered in severely immunocompromised HIV-infected patients with multi-organ involvement and fever, especially when renal failure is present. Microsporidial spores are usually seen in urine samples and in the involved organ. Albendazole therapy seems to be effective.
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Affiliation(s)
- S Fournier
- Department of Infectious Diseases, Saint-Louis Hospital, Paris, France
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Franzen C, Müller A. Cryptosporidia and microsporidia--waterborne diseases in the immunocompromised host. Diagn Microbiol Infect Dis 1999; 34:245-62. [PMID: 10403104 DOI: 10.1016/s0732-8893(99)00003-6] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Cryptosporidia and microsporidia are emerging parasitic pathogens in immunocompetent and immunocompromised individuals. Cryptosporidium infects several wild and domestic animals that excrete oocysts into the environment and contaminated water represents the major source of infection for humans. Waterborne transmission of Cryptosporidium is a major risk for humans and appropriate measures have to be taken to protect immunocompetent and immunocompromised individuals to become infected. For microsporidia, the sources and ways of transmission are not well documented. Although several animal hosts have been identified recently, the relevant reservoirs of human microsporidia are still unknown. Also, the routes of spreading are unknown. Is microsporidiosis a zoonotic disease that will be transmitted through close contact with infected animals or is contaminated surface water responsible for transmission and represents a relevant reservoir? This review is designed to give information on these two emerging intestinal parasites in a format that will be useful to clinical microbiologists, physicians interested in infectious diseases, and public health personnel.
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Affiliation(s)
- C Franzen
- Department of Internal Medicine I, University of Cologne, Germany
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Franzen C, Müller A. Molecular techniques for detection, species differentiation, and phylogenetic analysis of microsporidia. Clin Microbiol Rev 1999; 12:243-85. [PMID: 10194459 PMCID: PMC88917 DOI: 10.1128/cmr.12.2.243] [Citation(s) in RCA: 184] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Microsporidia are obligate intracellular protozoan parasites that infect a broad range of vertebrates and invertebrates. These parasites are now recognized as one of the most common pathogens in human immunodeficiency virus-infected patients. For most patients with infectious diseases, microbiological isolation and identification techniques offer the most rapid and specific determination of the etiologic agent. This is not a suitable procedure for microsporidia, which are obligate intracellular parasites requiring cell culture systems for growth. Therefore, the diagnosis of microsporidiosis currently depends on morphological demonstration of the organisms themselves. Although the diagnosis of microsporidiosis and identification of microsporidia by light microscopy have greatly improved during the last few years, species differentiation by these techniques is usually impossible and transmission electron microscopy may be necessary. Immunfluorescent-staining techniques have been developed for species differentiation of microsporidia, but the antibodies used in these procedures are available only at research laboratories at present. During the last 10 years, the detection of infectious disease agents has begun to include the use of nucleic acid-based technologies. Diagnosis of infection caused by parasitic organisms is the last field of clinical microbiology to incorporate these techniques and molecular techniques (e.g., PCR and hybridization assays) have recently been developed for the detection, species differentiation, and phylogenetic analysis of microsporidia. In this paper we review human microsporidial infections and describe and discuss these newly developed molecular techniques.
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Affiliation(s)
- C Franzen
- Department of Internal Medicine I, University of Cologne, 50924 Cologne,
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Leder K, Ryan N, Spelman D, Crowe SM. Microsporidial disease in HIV-infected patients: a report of 42 patients and review of the literature. SCANDINAVIAN JOURNAL OF INFECTIOUS DISEASES 1998; 30:331-8. [PMID: 9817510 DOI: 10.1080/00365549850160594] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
Microsporidiosis is recognized as an increasingly important infection, particularly in patients with human immunodeficiency virus (HIV) infection. In this retrospective study we have reviewed the clinical features, laboratory findings and management of 42 HIV positive patients co-infected with microsporidia. All patients had spores identified in faeces stained with a modified trichome blue stain. Patients were all markedly immunosuppressed (median CD4 20 cells/microl). Common symptoms included weight loss, diarrhoea, abdominal pain, anorexia and nausea. 29 patients were diagnosed with Enterocytozoon bieneusi infection; 13 were infected with Encephalitozoon intestinalis, and disseminated disease was confirmed in 8. Albendazole therapy in patients with E. intestinalis (but not E. bieneusi) resulted in good clinical response.
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Affiliation(s)
- K Leder
- Monash Medical Centre, Clayton, Victoria, Australia
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Katiyar SK, Edlind TD. In vitro susceptibilities of the AIDS-associated microsporidian Encephalitozoon intestinalis to albendazole, its sulfoxide metabolite, and 12 additional benzimidazole derivatives. Antimicrob Agents Chemother 1997; 41:2729-32. [PMID: 9420047 PMCID: PMC164197 DOI: 10.1128/aac.41.12.2729] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Recent reports have described the successful treatment of Encephalitozoon intestinalis infection in AIDS patients with albendazole. However, this compound is rapidly metabolized in vivo to albendazole sulfoxide, and furthermore it is only 1 of about 15 commercially developed benzimidazole derivatives. To compare the activities of albendazole, albendazole sulfoxide, and other benzimidazoles, an in vitro system involving infection of green monkey kidney cell (E6) monolayers with E. intestinalis spores was developed. After 14 days, the effects of benzimidazoles on spore production were determined. Ten of fourteen derivatives tested, including albendazole, were inhibitory at concentrations of 1 to 10 ng/ml. Derivatives modified at the 1 or 2 position were less active. Albendazole sulfoxide was 1.7-fold more inhibitory than albendazole but significantly less toxic to E6 cells, a finding that explains the clinical efficacy of this compound. Potential alternatives to albendazole are discussed. No albendazole-resistant E. intestinalis mutants were obtained following in vitro selection.
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Affiliation(s)
- S K Katiyar
- MCP-Hahnemann School of Medicine, Allegheny University of the Health Sciences, Philadelphia, Pennsylvania 19129, USA.
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Didier ES. Effects of albendazole, fumagillin, and TNP-470 on microsporidial replication in vitro. Antimicrob Agents Chemother 1997; 41:1541-6. [PMID: 9210681 PMCID: PMC163955 DOI: 10.1128/aac.41.7.1541] [Citation(s) in RCA: 77] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Presently, the two most commonly used drugs for treating microsporidiosis in persons with AIDS are albendazole and fumagillin. Albendazole is effective for treating disseminated infections due to Encephalitozoon spp. but is variably effective against Enterocytozoon bieneusi infections. Fumagillin is highly effective when used topically to treat ocular infections with Encephalitozoon hellem or Encephalitozoon intestinalis but is too toxic for systemic use. In this study, the fumagillin analog TNP-470 was assayed for antimicrosporidial activity in vitro. The MICs of TNP-470 at which 50% of isolates were killed (MIC50s) were 0.35 +/- 0.21 and 0.38 +/- 0.11 ng/ml for E. intestinalis and Vittaforma corneae, respectively, and were similar to the MIC50s of fumagillin for these organisms, which were 0.515 +/- 0.002 and 0.81 +/- 0.014 ng/ml, respectively. The MIC50 of albendazole for E. intestinalis was 8.0 +/- 4.23 ng/ml, significantly less (P < 0.01) than its MIC50 for V. corneae, which was 55.0 +/- 7.07 ng/ml. TNP-470 inhibited replication of E. intestinalis in RK-13 cells if it was given at the same time as infection or if treatment was initiated 7 days later. In addition, treatment of the infected cultures with TNP-470 at a dose of 10 ng/ml for 2 weeks, followed by discontinuation of the drug treatment, resulted in no significant increase in E. intestinalis shedding during the following 3 weeks in culture. Because TNP-470 acts against both E. intestinalis and V. corneae, and because TNP-470 was found by others to be less toxic in vivo, TNP-470 may be a promising new drug for the treatment of microsporidiosis.
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Affiliation(s)
- E S Didier
- Department of Microbiology, Tulane Regional Primate Research Center, Covington, Louisiana 70433, USA.
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Weber R, Deplazes P, Flepp M, Mathis A, Baumann R, Sauer B, Kuster H, Lüthy R. Cerebral microsporidiosis due to Encephalitozoon cuniculi in a patient with human immunodeficiency virus infection. N Engl J Med 1997; 336:474-8. [PMID: 9017940 DOI: 10.1056/nejm199702133360704] [Citation(s) in RCA: 105] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- R Weber
- Department of Medicine, University Hospital, Zurich, Switzerland
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Hollister WS, Canning EU, Colbourn NI, Aarons EJ. Encephalitozoon cuniculi isolated from the urine of an AIDS patient, which differs from canine and murine isolates. J Eukaryot Microbiol 1995; 42:367-72. [PMID: 7620460 DOI: 10.1111/j.1550-7408.1995.tb01595.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
A species of Encephalitozoon has been isolated from the urine of a patient with the acquired immunodeficiency syndrome and maintained in vitro in Madin Darby Canine Kidney cells. When examined by random amplified polymorphic DNA polymerase chain reaction the new isolate was found to differ from E. hellem and to have amplified products in common with murine and canine E. cuniculi. However, it more closely resembled the canine than the murine isolate. Sodium dodecylsulphate polyacrylamide gel electrophoresis differentiated between all three isolates of E. cuniculi, with a band at 42-45 kDa present in the murine isolate only, bands at 52 kDa present in the canine and human isolates but not the murine, and a single band at 60 kDa (murine) and 65 kDa (canine) replaced by two bands at 55 and 70 kDa in the human isolate. The 55 kDa and 70 kDa antigens were also revealed as characteristic bands of the human isolate by Western blotting. The study has thus revealed that the species Encephalitozoon cuniculi is not a homogeneous entity.
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Affiliation(s)
- W S Hollister
- Department of Biology, Imperial College of Science, Technology & Medicine, London, United Kingdom
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van Gool T, Dankert J. Human microsporidiosis: Clinical, diagnostic and therapeutic aspects of an increasing infection. Clin Microbiol Infect 1995; 1:75-85. [PMID: 11866734 DOI: 10.1111/j.1469-0691.1995.tb00450.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Human microsporidiosis is a parasitic infection due to species of four different genera: Encephalitozoon; Enterocytozoon; Nosema; and Pleistophora. Although well known as a cause of disease in animals, microsporidiosis was only occasionally reported in humans. Recently, in human immunodeficiency virus (HIV)-infected patients, microsporidia belonging to Encephalitozoon and Enterocytozoon species have proved to be important opportunistic pathogens. Enterocytozoon bieneusi is associated with chronic intermittent diarrhea, cholangiopathy and sinusitis whereas Encephalitozoon intestinalis, Encephalitozoon hellem and Encephalitozoon cuniculi, the three Encephalitozoon species found in humans, are associated with diarrhea, rhinosinusitis, keratoconjunctivitis, nephritis and hepatitis. Diagnosis of microsporidial infections in humans was until recently an invasive, laborious procedure including electron microscopy of small intestine biopsies. However, new simple staining methods using Uvitex 2B or modified trichrome stain for feces and other body fluids have facilitated clinical diagnosis as well as drug evaluation and epidemiological studies. The application of monoclonal antibodies and molecular techniques such as the polymerase chain reaction have further improved microsporidial diagnosis. Treatment of Entero. bieneusi has, until now, been unsuccessful whereas albendazole has proved to be an effective treatment for Encephalitozoon species infection. Identification of effective treatment for Entero. bieneusi infections and further study of the pathogenicity of these microsporidial infections in immunocompetent hosts are important future challenges.
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Affiliation(s)
- Tom van Gool
- Department of Medical Microbiology, Academic Medical Center, Amsterdam, The Netherlands
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