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Hinney B, Sak B, Joachim A, Kváč M. More than a rabbit's tale - Encephalitozoon spp. in wild mammals and birds. Int J Parasitol Parasites Wildl 2016; 5:76-87. [PMID: 28560162 PMCID: PMC5439460 DOI: 10.1016/j.ijppaw.2016.01.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Revised: 12/23/2015] [Accepted: 01/05/2016] [Indexed: 11/25/2022]
Abstract
Within the microsporidian genus Encephalitozoon, three species, Encephalitozoon cuniculi, Encephalitozoon hellem and Encephalitozoon intestinalis have been described. Several orders of the Class Aves (Passeriformes, Psittaciformes, Apodiformes, Ciconiiformis, Gruiformes, Columbiformes, Suliformes, Podicipediformes, Anseriformes, Struthioniformes, Falconiformes) and of the Class Mammalia (Rodentia, Lagomorpha, Primates, Artyodactyla, Soricomorpha, Chiroptera, Carnivora) can become infected. Especially E. cuniculi has a very broad host range while E. hellem is mainly distributed amongst birds. E. intestinalis has so far been detected only sporadically in wild animals. Although genotyping allows the identification of strains with a certain host preference, recent studies have demonstrated that they have no strict host specificity. Accordingly, humans can become infected with any of the four strains of E. cuniculi as well as with E. hellem or E. intestinalis, the latter being the most common. Especially, but not exclusively, immunocompromised people are at risk. Environmental contamination with as well as direct transmission of Encephalitozoon is therefore highly relevant for public health. Moreover, endangered species might be threatened by the spread of pathogens into their habitats. In captivity, clinically overt and often fatal disease seems to occur frequently. In conclusion, Encephalitozoon appears to be common in wild warm-blooded animals and these hosts may present important reservoirs for environmental contamination and maintenance of the pathogens. Similar to domestic animals, asymptomatic infections seem to occur frequently but in captive wild animals severe disease has also been reported. Detailed investigations into the epidemiology and clinical relevance of these microsporidia will permit a full appraisal of their role as pathogens.
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Affiliation(s)
- Barbara Hinney
- Institute of Parasitology, Department of Pathobiology, University of Veterinary Medicine Vienna, Veterinaerplatz 1, A-1210 Vienna, Austria
| | - Bohumil Sak
- Institute of Parasitology, Biology Centre of the Academy of Sciences of the Czech Republic, v.v.i. Branišovská 31, 370 05 České Budějovice, Czech Republic
| | - Anja Joachim
- Institute of Parasitology, Department of Pathobiology, University of Veterinary Medicine Vienna, Veterinaerplatz 1, A-1210 Vienna, Austria
| | - Martin Kváč
- Institute of Parasitology, Biology Centre of the Academy of Sciences of the Czech Republic, v.v.i. Branišovská 31, 370 05 České Budějovice, Czech Republic
- Faculty of Agriculture, University of South Bohemia in České Budějovice, Studentská 13, 370 05 České Budějovice, Czech Republic
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Rosell J, Máinez M, Didier ES, Bowers LC, Marco A, Juan-Sallés C. Encephalitozoon hellem infection in aviary passerine and psittacine birds in Spain. Vet Parasitol 2016; 219:57-60. [PMID: 26921040 DOI: 10.1016/j.vetpar.2016.01.022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Revised: 01/26/2016] [Accepted: 01/29/2016] [Indexed: 10/22/2022]
Abstract
A European goldfinch (Carduelis carduelis), a canary (Serinus canaria), and a lovebird (Agapornis roseicollis) captive-bred at three different private aviaries in Spain were submitted for necropsy with a history of weakness and ruffled feathers, weight loss associated with glossitis, and respiratory disease, respectively. Microscopically, enterocytes in the jejunum and ileum contained colonies of gram- and Stamp-positive, oval to elliptical microorganisms within parasitophorous vacuoles in the apical cytoplasm. Nested PCR using MSP primers that target microsporidian RNA genes produced amplicons of expected size for Encephalitozoon species, and analysis of forward and reverse DNA sequences confirmed the presence of Encephalitozoon hellem in all cases. The main cause of death of all three birds consisted of concurrent infections. However, intestinal encephalitozoonosis may have contributed to exacerbated catabolism. Encephalitozoonosis (or microsporidiosis) has been rarely described in passerine birds.
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Affiliation(s)
- J Rosell
- Noah's Path, Arquitecto Santiago Pérez Aracil 30 bajo, 03203 Elche, Alicante, Spain.
| | - M Máinez
- Centro Veterinario La Marina Exóticos, Arquitecto Santiago Pérez Aracil 30 bajo, 03203 Elche, Alicante, Spain
| | - E S Didier
- Division of Microbiology, Tulane National Primate Research Center, Covington, LA 70433, USA; Department of Tropical Medicine, School of Public Health and Tropical Medicine, Tulane University, New Orleans, LA 70112, USA
| | - L C Bowers
- Department of Tropical Medicine, School of Public Health and Tropical Medicine, Tulane University, New Orleans, LA 70112, USA
| | - A Marco
- UD Histologia i Anatomia Patològica, Facultat de Veterinària, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain
| | - C Juan-Sallés
- Noah's Path, Arquitecto Santiago Pérez Aracil 30 bajo, 03203 Elche, Alicante, Spain
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Molecular characterization and genotyping of human related microsporidia in free-ranging and captive pigeons of Tehran, Iran. INFECTION GENETICS AND EVOLUTION 2013. [DOI: 10.1016/j.meegid.2013.10.007] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Nakamura A, Homem C, Garcia S, Meireles M. Ceratoconjuntivite por Encephalitozoon hellem em periquitos agapornis (Agapornis spp.) no Brasil: relato de caso. ARQ BRAS MED VET ZOO 2010. [DOI: 10.1590/s0102-09352010000400009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Relata-se um caso de ceratoconjuntivite causada por Encephalitozoon hellem em agapornis (Agapornis spp.) adultos, provenientes de um criatório comercial. Cinco animais apresentaram sinais clínicos de ceratoconjuntivite, blefaroespasmo e blefaroedema bilateral, com presença de secreção seropurulenta. Amostras fecais foram colhidas e foi realizado exame coproparasitológico, com resultado negativo. Dois animais foram necropsiados, sendo detectados, em impressões de raspado de conjuntiva ocular, esporos e outros estádios evolutivos de Microsporidium. A confirmação do diagnóstico foi feita pela reação em cadeia de polimerase e sequenciamento de fragmentos amplificados, com utilização de primers específicos para o gene da subunidade 18S do rRNA de E. hellem. A análise dos fragmentos amplificados demonstrou 100% de similaridade com outras sequências de E. hellem publicadas no GenBank. Este é primeiro relato de infecção por E. hellem em aves no Brasil.
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Sak B, Kasicková D, Kvác M, Kvetonová D, Ditrich O. Microsporidia in exotic birds: intermittent spore excretion of Encephalitozoon spp. in naturally infected budgerigars (Melopsittacus undulatus). Vet Parasitol 2009; 168:196-200. [PMID: 20006443 DOI: 10.1016/j.vetpar.2009.11.012] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2009] [Revised: 11/06/2009] [Accepted: 11/13/2009] [Indexed: 11/29/2022]
Abstract
Nine naturally infected asymptomatic budgerigars (Melopsittacus undulatus) were screened daily for microsporidia spore excretion during a 30-day period and the localization of infection was evaluated using microscopy and molecular methods. While the microscopic examination revealed 2.4% positivity out of all fecal samples, using PCR the positivity was 10x higher (24.6%). All nine budgerigars excreted microsporidial spores intermittently in irregular intervals with 1-11-day long interruptions. Most of the birds were infected simultaneously with Encephalitozoon cuniculi and Encephalitozoon hellem. While histological and TEM examination failed to confirm the presence of microsporidial spores in tissues, the PCR detected microsporidial DNA mostly in the small intestine, liver and lungs of four selected budgerigars dissected. Despite the chronic infection proved using molecular methods, no clinical signs of disease were observed during monitoring and no pathological findings were found during dissection.
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Affiliation(s)
- Bohumil Sak
- Institute of Parasitology, Biology Centre of the Academy of Sciences of the Czech Republic, v.v.i., Branisovská 31, Ceské Budejovice, Czech Republic.
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Kašičková D, Sak B, Kváč M, Ditrich O. Sources of potentially infectious human microsporidia: Molecular characterisation of microsporidia isolates from exotic birds in the Czech Republic, prevalence study and importance of birds in epidemiology of the human microsporidial infections. Vet Parasitol 2009; 165:125-30. [DOI: 10.1016/j.vetpar.2009.06.033] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2009] [Revised: 06/23/2009] [Accepted: 06/23/2009] [Indexed: 10/20/2022]
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Johny S, Larson TM, Solter LF, Edwards KA, Whitman DW. Phylogenetic characterization of Encephalitozoon romaleae (Microsporidia) from a grasshopper host: relationship to Encephalitozoon spp. infecting humans. INFECTION GENETICS AND EVOLUTION 2008; 9:189-95. [PMID: 19027883 DOI: 10.1016/j.meegid.2008.10.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2008] [Revised: 10/21/2008] [Accepted: 10/26/2008] [Indexed: 11/18/2022]
Abstract
Encephalitozoon species are the most common microsporidian pathogens of humans and domesticated animals. We recently discovered a new microsporidium, Encephalitozoon romaleae, infecting the eastern lubber grasshopper Romalea microptera. To understand its evolutionary relationships, we compared partial gene sequences of alpha- and beta-tubulin and methionine aminopeptidase 2 enzyme from this and related species. We also analyzed the rRNA internal transcribed spacer. Based on tubulin and MetAP-2 gene phylogenetic analysis, E. romaleae clustered with the Encephalitzoon group with strong bootstrap support (>99%). Within the Encephalitozoon clade, E. romaleae clustered with Encephalitozoon hellem for both the beta-tubulin and MetAP-2 phylogenies based on ML tree. The alpha-tubulin based ML tree, however, placed the new microsporidium closer to Encephalitozoon cuniculi. The rRNA internal transcribed spacer region of E. romaleae has 91% homology with E. hellem.
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Affiliation(s)
- Shajahan Johny
- Illinois State University, 4120 Department of Biological Sciences, Illinois State University, Normal, IL 61790-4120, USA
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Müller MG, Kinne J, Schuster RK, Walochnik J. Outbreak of microsporidiosis caused by Enterocytozoon bieneusi in falcons. Vet Parasitol 2007; 152:67-78. [PMID: 18166273 DOI: 10.1016/j.vetpar.2007.11.019] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2007] [Revised: 11/10/2007] [Accepted: 11/16/2007] [Indexed: 11/26/2022]
Abstract
Four falcons from a private collection of 137 falcons in Abu Dhabi (UAE) died suddenly in summer 2005. In order to screen for a possible disease among the remaining falcons in the aviary, all other birds were caught, examined and treated if necessary. Most of the falcons suffered from massive lice infestation and 74 falcons additionally from a heavy Caryospora sp. burden. Endoscopy revealed yellowish plaques on intestines, livers or kidneys in 70 birds (51.1% morbidity). Proliferative serositis was seen in 17 out of 24 necropsied birds with plaques on intestines, livers or kidneys, which did not resemble any known disease in falcons. However, apart from 20 falcons, which died within a 6-week period after the initial examinations due to advanced disease stages, all other falcons responded well to the treatment with dimetridazole (Emtryl), indicating protozoal disease. Immunohistochemistry confirmed the presence of microsporidial antigen. The final diagnosis of Enterocytozoon (E.) bieneusi genotype D was confirmed with materials from 6 birds by PCR and sequencing. To our knowledge this is the first report of microsporidiosis caused by E. bieneusi in raptors in general and in falcons in particular. However, it is still unclear for how long E. bieneusi was present in the falcon flock, and which role it played in the development of the disease. Predisposing factors such as high temperature and overcrowding in the aviary induced immune suppression causing massive lice infestation as well as coccidiosis, thus paving the way for invasion with microsporidial spores.
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Affiliation(s)
- M G Müller
- Abu Dhabi Falcon Hospital, EAD, P.O. Box 45553, Abu Dhabi, United Arab Emirates.
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Kasicková D, Sak B, Kvác M, Ditrich O. Detection of Encephalitozoon cuniculi in a new host--cockateel (Nymphicus hollandicus) using molecular methods. Parasitol Res 2007; 101:1685-8. [PMID: 17805572 DOI: 10.1007/s00436-007-0720-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2007] [Accepted: 08/08/2007] [Indexed: 11/29/2022]
Abstract
A total of 123 avian faecal specimens randomly collected in Bohemian commercial aviaries, Zoo parks and countryside were screened for the presence of human pathogenic microsporidia by both calcofluor M2R staining and polymerase chain reaction. Of these, no positive sample was detected using microscopical examination, and one isolate was detected by polymerase chain reaction and identified as Encephalitozoon cuniculi. Cockateel (Nymphicus hollandicus) represents a new avian host of this microsporidian.
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Affiliation(s)
- D Kasicková
- Faculty of Biological Science, University of South Bohemia, Ceské Budejovice, Czech Republic.
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Slodkowicz-Kowalska A, Graczyk TK, Tamang L, Jedrzejewski S, Nowosad A, Zduniak P, Solarczyk P, Girouard AS, Majewska AC. Microsporidian species known to infect humans are present in aquatic birds: implications for transmission via water? Appl Environ Microbiol 2006; 72:4540-4. [PMID: 16820441 PMCID: PMC1489349 DOI: 10.1128/aem.02503-05] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human microsporidiosis, a serious disease of immunocompetent and immunosuppressed people, can be due to zoonotic and environmental transmission of microsporidian spores. A survey utilizing conventional and molecular techniques for examining feces from 570 free-ranging, captive, and livestock birds demonstrated that 21 animals shed microsporidian spores of species known to infect humans, including Encephalitozoon hellem (20 birds; 3.5%) and Encephalitozoon intestinalis (1 bird; 0.2%). Of 11 avian species that shed E. hellem and E. intestinalis, 8 were aquatic birds (i.e., common waterfowl). The prevalence of microsporidian infections in waterfowl (8.6%) was significantly higher than the prevalence of microsporidian infections in other birds (1.1%) (P < 0.03); waterfowl fecal droppings contained significantly more spores (mean, 3.6 x 10(5) spores/g) than nonaquatic bird droppings contained (mean, 4.4 x 10(4) spores/g) (P < 0.003); and the presence of microsporidian spores of species known to infect humans in fecal samples was statistically associated with the aquatic status of the avian host (P < 0.001). We demonstrated that a single visit of a waterfowl flock can introduce into the surface water approximately 9.1 x 10(8) microsporidian spores of species known to infect humans. Our findings demonstrate that waterborne microsporidian spores of species that infect people can originate from common waterfowl, which usually occur in large numbers and have unlimited access to surface waters, including waters used for production of drinking water.
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Affiliation(s)
- Anna Slodkowicz-Kowalska
- Departmetn of Biology and Medical Parasitology, Poznan University of Medical Sciences, Poznan, Poland
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11
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Gelis S, Raidal SR. Microsporidiosis in a flock of tricolor parrot finches (Erythrura tricolor). Vet Clin North Am Exot Anim Pract 2006; 9:481-6. [PMID: 16931363 DOI: 10.1016/j.cvex.2006.05.032] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The lesions caused by a microsporidian infection in a flock of tricolor parrot finches (Erythrura tricolor) are described. Affected birds had a widespread nodular to diffuse granulomatous inflammation of the serosal surfaces of the gastrointestinal tract, peritoneum, perirenal airsacs and connective tissue, bone marrow, dura, and conjunctiva. This was composed predominantly of foamy macrophages containing numerous intracytoplasmic microsporidia measuring 1 to 2 microm. Ultrastructural features consistent with microsporidia were the presence of a coiled polar filament and an electrode-dense outer surface and thick electron-lucent capsule. Differential diagnoses included infection with intracellular organisms, including coccidian and other apicomplexan parasites, such as lsospora, Eimeria, and blood parasites; Chlamydophilosis; disseminated mycobacteriosis; and other bacterial and fungal species.
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Affiliation(s)
- Stacey Gelis
- Coolum Veterinary Surgery, 43 Coolum-Yandina Road, Coolum Beach, QLD, 4573, Australia
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12
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Childs-Sanford SE, Garner MM, Raymond JT, Didier ES, Kollias GV. Disseminated microsporidiosis due to Encephalitozoon hellem in an Egyptian fruit bat (Rousettus aegyptiacus). J Comp Pathol 2006; 134:370-3. [PMID: 16709419 DOI: 10.1016/j.jcpa.2006.01.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2005] [Accepted: 01/03/2006] [Indexed: 11/21/2022]
Abstract
Disseminated microsporidiosis was diagnosed in an adult female Egyptian fruit bat that died unexpectedly in a zoo. Gross findings, which were minimal, included poor body condition, bilateral renomegaly, and mottling of the liver. Histopathological lesions, which were particularly pronounced in the urogenital tract and liver, consisted primarily of inflammation associated with intracytoplasmic microsporidian spores. Polymerase chain reaction -based methods were used to establish the identity of the microsporidian as Encephalitozoon hellem. E. hellem is an emerging cause of human and avian disease, manifested mainly as opportunistic infection in immunosuppressed patients. This report describes the first documented case of E. hellem in a non-human mammalian species.
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Affiliation(s)
- S E Childs-Sanford
- Section of Wildlife Health, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853
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Phalen DN, Logan KS, Snowden KF. Encephalitozoon hellem infection as the cause of a unilateral chronic keratoconjunctivitis in an umbrella cockatoo (Cacatua alba). Vet Ophthalmol 2006; 9:59-63. [PMID: 16409247 DOI: 10.1111/j.1463-5224.2005.00434.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
An umbrella cockatoo (Cacatua alba) was presented with a keratoconjunctivitis of 9 months' duration that was refractory to antibacterial and antifungal treatments. Microsporidian-type spores were observed in calcofluor M2R-stained cytological preparations of debrided corneal epithelium. Hematoxylin and eosin-stained sections of a conjunctival biopsy also showed a small number of intracellular parasites. Microsporidial DNA was detected by polymerase chain reaction in DNA extracted from the remaining biopsy material. Sequence analysis of the small subunit ribosomal RNA gene identified the microsporidium as Encephalitozoon hellem. The cockatoo was treated with oral albendazole for 3 months with resolution of the signs, and then again for 4 months when the signs returned. Since then, the bird has remained healthy for 2 years. This is the second report of a microsporidial keratoconjunctivitis in a bird, and the first report of an E. hellem infection in a cockatoo. Ophthalmologists should consider E. hellem as a possible cause of a keratoconjunctivitis in parrots that is refractory to treatment with traditional antimicrobials.
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Affiliation(s)
- David N Phalen
- Department of Veterinary Pathobiology, College of Veterinary Medicine, Texas A&M University, College Station, TX 77843-4467, USA
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Haro M, Izquierdo F, Henriques-Gil N, Andrés I, Alonso F, Fenoy S, del Aguila C. First detection and genotyping of human-associated microsporidia in pigeons from urban parks. Appl Environ Microbiol 2005; 71:3153-7. [PMID: 15933015 PMCID: PMC1151808 DOI: 10.1128/aem.71.6.3153-3157.2005] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Microsporidia are ubiquitous opportunistic parasites in nature infecting all animal phyla, and the zoonotic potential of this parasitosis is under discussion. Fecal samples from 124 pigeons from seven parks of Murcia (Spain) were analyzed. Thirty-six of them (29.0%) showed structures compatible with microsporidia spores by staining methods. The DNA isolated from 26 fecal samples (20.9%) of microsporidia-positive pigeons was amplified with specific primers for the four most frequent human microsporidia. Twelve pigeons were positive for only Enterocytozoon bieneusi (9.7%), 5 for Encephalitozoon intestinalis (4%), and one for Encephalitozoon hellem (0.8%). Coinfections were detected in eight additional pigeons: E. bieneusi and E. hellem were detected in six animals (4.8%); E. bieneusi was associated with E. intestinalis in one case (0.8%); and E. hellem and E. intestinalis coexisted in one pigeon. No positive samples for Encephalitozoon cuniculi were detected. The internally transcribed spacer genotype could be completed for one E. hellem-positive pigeon; the result was identical to the genotype A1 previously characterized in an E. hellem Spanish strain of human origin. To our knowledge, this is the first time that human-related microsporidia have been identified in urban park pigeons. Moreover, we can conclude that there is no barrier to microsporidia transmission between park pigeons and humans for E. intestinalis and E. hellem. This study is of environmental and sanitary interest, because children and elderly people constitute the main visitors of parks and they are populations at risk for microsporidiosis. It should also contribute to the better design of appropriate prophylactic measures for populations at risk for opportunistic infections.
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Affiliation(s)
- M Haro
- Laboratorio de Genética, Universidad San Pablo-CEU, Boadilla del Monte, Madrid, Spain
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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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Abstract
Microsporidia have emerged as causes of infectious diseases in AIDS patients, organ transplant recipients, children, travelers, contact lens wearers, and the elderly. These organisms are small single-celled, obligate intracellular parasites that were considered to be early eukaryotic protozoa but were recently reclassified with the fungi. Of the 14 species of microsporidia currently known to infect humans, Enterocytozoon bieneusi and Encephalitozoon intestinalis are the most common causes of human infections and are associated with diarrhea and systemic disease. Species of microsporidia infecting humans have been identified in water sources as well as in wild, domestic, and food-producing farm animals, raising concerns for waterborne, foodborne, and zoonotic transmission. Current therapies for microsporidiosis include albendazole which is a benzimidazole that inhibits microtubule assembly and is effective against several microsporidia, including the Encephalitozoon species, but is less effective against E. bieneusi. Fumagillin, an antibiotic and anti-angiogenic compound produced by Aspergillus fumigatus, is more broadly effective against Encephalitozoon spp. and Enterocytozoon bieneusi but is toxic when administered systemically to mammals. Gene target studies have focused on methionine aminopeptidase 2 (MetAP2) for characterizing the mechanism of action and for identifying more effective, less toxic fumagillin-related drugs. Polyamine analogues have shown promise in demonstrating anti-microsporidial activity in culture and in animal models, and a gene encoding topoisomerase IV was identified in Vittaforma corneae, raising prospects for studies on fluoroquinolone efficacy against microsporidia.
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Affiliation(s)
- Elizabeth S Didier
- Division of Microbiology, Tulane National Primate Research Center, Covington, LA 70433, USA.
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Barton CE, Phalen DN, Snowden KF. Prevalence of Microsporidian Spores Shed by Asymptomatic Lovebirds: Evidence for a Potential Emerging Zoonosis. J Avian Med Surg 2003. [DOI: 10.1647/2002-011] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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