Equine rhinosporidiosis in Buenos Aires, Argentina.

Rhinosporidiosis is caused by Rhinosporidium seeberi, a parasitic organism of the family Rhinosporideacea family, class Micomycetozoa. The disease is endemic in India; however, some cases were reported in Europe, Africa, North America, and South America. The aim of the present study is to report three cases of rhinosporidiosis in wild horses in different cities of Buenos Aires province, Argentina. We confirm the presence of R. seeberi in the analyzed samples using histopathological and PCR sequencing techniques.

Nasal Rhinosporidiosis: Clinical Presentation, Clinical Findings, and Outcome in Dogs.

The purpose of this study was to describe the clinical presentation, imaging findings, and outcome in 10 dogs diagnosed with Rhinosporidium seeberi infections. Histopathology and cytology records were searched at a veterinary teaching hospital and a veterinary diagnostic laboratory to identify dogs with rhinosporidiosis. Medical records were reviewed for clinical, imaging, endoscopic, and surgical findings. Outcome was determined via evaluation of records and, where possible, telephone conversation with the primary care veterinarian and/or owner. Young to middle-aged large-breed dogs with an approximately equal sex distribution were represented. Unilateral signs predominated. Diagnosis was confirmed by histopathology in 9 cases, and cytology was diagnostic in only 1 of 3 cases. Histopathology was superior to cytology. Masses were soft tissue and contrast enhancing with no evidence of bony lysis on computed tomography (2 dogs). Direct or rhinoscopic (2 dogs) visualization revealed white to yellow pinpoint foci. Surgical resection (4 dogs) can result in long-term disease-free periods (up to 2659 days), although repeat surgery can be required. Dapsone was well tolerated in 1 dog, and relapse was not noted despite incomplete surgical resection (follow-up 749 days). Visualization of pale foci on a rostral intranasal mass in an endemic region should prompt consideration of rhinosporidiosis.

Rhinosporidiosis in horses / Rinosporidiose em equinos

Rhinosporidiosis is a disease caused by Rhinosporidium seeberi, an aquatic protist of the class Mesomycetozoa. It primarily affects the nasal mucosa and transmission is associated with contaminated water contact. This report describes seven cases of rhinosporidiosis in horses in Rio Grande do Sul covering the period of 13 years. The disease predominantly affected Crioulo and thoroughbred horses. No apparent gender predisposition occurs, and age ranged from two to 25 years, with a median of 10 years. The gross aspects were characterized by unilateral (85.7%, 6/7) or bilateral (14.3%, 1/7) polyps. These were soft to friable, whitish to pink, cauliflower-like, with an irregular, sometimes ulcerated surface, measuring 2.5 to 6.0cm in diameter. There was a severe inflammatory infiltrate of the submucosa was observed, associated with moderate proliferation of the epithelium, and numerous rounded structures were identified compatible with sporangia of R. seeberi. Rhinosporidiosis should be included in the differential diagnosis of other conditions affecting the respiratory tract of horses, and it is important to perform histopathology for diagnosis.(AU)

A rinosporidiose é uma doença causada por Rhinosporidium seeberi, protista aquático da classe Mesomycetozoa. Acomete principalmente a mucosa nasal e a transmissão está associada ao contato com água contaminada. Este trabalho descreve sete casos de rinosporidiose em equinos no Rio Grande do Sul em um período de 13 anos. A doença afetou predominantemente cavalos de raça, como Crioulo e Puro Sangue Inglês, sem predisposição sexual evidente e a idade variou de dois a 25 anos, com a mediana de 10 anos. Macroscopicamente foram caracterizadas por pólipos unilaterais (85,7%; 6/7) ou bilaterais (14,3%; 1/7). Os pólipos eram macios a friáveis, esbranquiçados a róseos, com aspecto de couve flor e com superfície irregular, por vezes ulcerada, medindo 2,5 a 6,0cm de diâmetro. Havia infiltrado inflamatório piogranulomatoso acentuado na submucosa associado à moderada proliferação do epitélio e numerosas estruturas arredondadas compatíveis com esporângios de R. seeberi. A rinosporidiose deve ser incluída no diagnóstico diferencial de outras patologias que acometem o trato respiratório de equinos, sendo importante a realização da histopatologia para diagnóstico.(AU)

Rhinosporidiosis in African reed frogs Hyperolius spp. caused by a new species of Rhinosporidium.

We report the identification of a new Rhinosporidium species (Dermocystida, Mesomycetozoea) infecting amphibian hosts, while showing a species specificity for African reed frogs of the genus Hyperolius. Large dermal cysts (sporangia) of R. rwandae sp. nov. were observed in 18% of H. lateralis and similar cysts in 0.7% of H. viridiflavus surveyed. Fully developed R. rwandae cysts are about 500 to 600 µm in diameter and sealed from the frog tissue by a thick chitinous wall. Some cysts were filled with numerous round-oval basophilic microspores of 8 to 12 µm diameter. With the exception of legs, nodules were visible over the complete torso surface including the vocal sac of males, but the most affected skin region was the area around the cloaca. Behavior, condition, and lifespan of infected frogs do not seem to be distinct from that of healthy individuals. The mode of infection remains unknown, but we hypothesize that the infectious life stage reaches the dermis via the intraepidermal ducts of the skin glands. Molecular evidence places the new frog pathogen as a sister species of the human pathogen R. seeberi.

Equine laryngeal rhinosporidiosis in western Canada.

A 12-year-old female Argentinean Warmblood mare was evaluated because of respiratory noise. The horse resided in Calgary, Alberta, Canada, but had been imported from Argentina 28 months prior to presentation. Endoscopy of the upper respiratory tract revealed a single polypoid mass on the left arytenoid. The mass was surgically excised and was diagnosed histologically as rhinosporidiosis. Polymerase chain reaction and DNA sequencing were used to confirm the etiological agent. Four weeks postoperatively, endoscopy was repeated, revealing recurrence of the original lesion with multiple additional polypoid masses on the larynx and in the oropharynx. Resolution of the disease had not been attained at the time of publication. The current report outlines a case of rhinosporidiosis in an unusual anatomical and geographic location. The infection most likely originated in Argentina, with a prolonged subclinical phase. Due to increased travel of human beings and animals, there is potential for the introduction of exotic diseases into nonendemic areas.

Nasal rhinosporidiosis in two dogs native to the upper Mississippi river valley region.

Two dogs, 4 and 7 years of age, were presented for evaluation and treatment of excessive sneezing. Physical examinations in both cases were within acceptable limits except for the presence of a single mass in the left nasal passage in the first case and left-sided nasal discharge in the second case. Rhinoscopy was used to visualize the nasal masses, and in both cases a single mass was surgically removed. Impression smears and histopathology submitted from each mass revealed lymphoplasmacytic and neutrophilic inflammation with spores typical of Rhinosporidium seeberi. These are the first reported cases of nasal rhinosporidiosis in two dogs native to the Upper Mississippi River Valley area with no travel history outside the region.

Concurrent nasal adenocarcinoma and rhinosporidiosis in a cat.

A 10-year-old, neutered, male Domestic Shorthair cat was presented to the teaching hospital for labored breathing, anorexia, and weight loss of several months duration. External examination revealed distortion of the bridge of the nose and pink fleshy polyps protruding from each nostril. The cat was euthanized and submitted for postmortem examination. In addition to the external findings, the nasal cavity had extensive bone and cartilage loss and contained a tan firm mass in the caudal region of the nasal cavity near the cribriform plate. On histologic examination, the mass was a nasal adenocarcinoma, and the polyps were composed of hyperplastic nasal epithelium and submucosal stroma that contained sporangia consistent with Rhinosporidium seeberi.

Laryngeal rhinosporidiosis in a Belgian warmblood horse.

In Belgium and even in northern Europe Rhinosporidium seeberi has not been reported in autochtonous people or animals. In this paper, the authors report the first observation of laryngeal masses, caused by Rhinosporidium seeberi, in a Belgian Warmblood horse. Moreover, laryngeal rhinosporidiosis is extremely rare since this localisation is only described in four human cases.

Nasal rhinosporidiosis in a mule.

A mass was removed from the nostril of a mule that exhibited unilateral epistaxis and nasal discharge. Impression smears revealed oval structures consistent with spores of Rhinosporidium seeberi. Microscopically, the mass was composed of fibrovascular granulomatous tissue containing sporangia R. seeberi. Surgical excision and antifungal treatment proved curative.

Equine rhinosporidiosis in United Kingdom.

We report 4 cases of equine rhinosporidiosis in the United Kingdom. These cases provide evidence of spread of infectious agents from rhinosporidiosis-endemic areas to nonendemic areas by increased international movement of livestock. Surveillance should continue for this infective agent of potential relevance for numerous species, including humans.

Cytologic identification of immature endospores in a dog with rhinosporidiosis.

An 8-year-old, intact, male Labrador Retriever was presented to the Boren Veterinary Medical Teaching Hospital at Oklahoma State University with a 2-month history of severe sneezing episodes that resulted in epistaxis and bilateral sanguineous discharge. Rhinoscopy revealed a small polypoid mass, and specimens were obtained for histopathology. Microscopic examination of formalin-fixed tissue specimens revealed organisms consistent with Rhinosporidium seeberi. The mass was surgically excised and impression smears were made for cytology examination. Smears revealed high numbers of endospores, typical of those previously described for R seeberi. In addition, numerous smaller structures, presumed to be immature endospores, were noted. The immature endospores were morphologically distinct from mature endospores and have not been described previously. Recognition of immature forms of Rhinosporidium may help prevent misidentification of the organism or misdiagnosis of a dual infection.

Molecular evidence for multiple host-specific strains in the genus Rhinosporidium.

The taxonomic relationship of Rhinosporidium seeberi with other organisms remained controversial for over a century. Recently, molecular studies have shown R. seeberi to be a protistal microbe in the newly described class Mesomycetozoea at the animal-fungal boundary. Phylogenetic analyses of R. seeberi using 18S small-subunit (SSU) rRNA genes from several hosts suggested Rhinosporidium as a monotypic genus. To test this hypothesis, the internal transcribed spacer 1 (ITS1), 5.8S, and ITS2 from eight humans, two swans, and a dog with rhinosporidiosis were sequenced. The ITS regions were amplified by PCR using a primer designed from a unique region of R. seeberi's 18S SSU rRNA genes in combination with the ITS4 universal primer. In addition, the universal ITS4 and ITS5 primers were also used. R. seeberi's ITS sequences showed differences in the numbers of nucleotides among strains. For instance, the eight human ITS sequences were uniformly similar with only a few mismatches and approximately 1,060 bp long. In contrast, sequences from one of the swans and the dog were 1,356 bp and approximately 1,147 bp long, respectively. Clustal analysis of all of the ITS sequences showed multiple 50- to 60-bp gaps and several mismatches among them. Parsimony analysis placed the Rhinosporidium ITS sequences in three well-supported sister groups according to the hosts' identities. This analysis strongly suggests that the genus Rhinosporidium may possess multiple host-specific strains. No correlation was found between this finding and the phenotypic features of R. seeberi in the studied samples.

Lacazia loboi and Rhinosporidium seeberi: a genomic perspective.

In the past five years, with the use of molecular strategies the phylogenetic affinities of the two more resilient pathogens studied in medical mycology, Lacazia loboi and Rhinosporidium seeberi were finally deciphered. These studies found that L. loboi was the sister taxon to Paraccidioides brasiliensis, and R. seeberi was closely related to protistan spherical aquatic fish pathogens, located at the point were animals diverged from the fungi, in the class Mesomycetozoea. These initial studies indicated that a molecular strategy was the ideal approach to further understand these anomalous pathogens. However, the limited amount of information gathered so far from few DNA sequences, although crucial to place these organisms in the tree of life and to take a glance to their ecological preferences, did not provide answers to other important traits. In the following pages we discuss a genomic perspective for both pathogens and the benefit that such information could generate to understand more about these two uncultivated pathogens.

Lacazia loboi and Rhinosporidium seeberi: a genomic perspective

In the past five years, with the use of molecular strategies the phylogenetic affinities of the two more resilient pathogens studied in medical mycology, Lacazia loboi and Rhinosporidium seeberi were finally deciphered. These studies found that L. loboi was the sister taxon to Paraccidioides brasiliensis, and R. seeberi was closely related to protistan spherical aquatic fish pathogens, located at the point were animals diverged from the fungi, in the class Mesomycetozoea. These initial studies indicated that a molecular strategy was the ideal approach to further understand these anomalous pathogens. However, the limited amount of information gathered so far from few DNA sequences, although crucial to place these organisms in the tree of life and to take a glance to their ecological preferences, did not provide answers to other important traits. In the following pages we discuss a genomic perspective for both pathogens and the benefit that such information could generate to understand more about these two uncultivated pathogens.

Rhinosporidiosis in a cat.

A polypoid nasal mass from an adult cat was submitted for routine biopsy examination and was found to contain sporangia and sporangiospores consistent with Rhinosporidium seeberi. Inflammatory infiltrates were moderate and pyogranulomatous to lymphohistiocytic and were associated with hyperplasia of the transitional nasal epithelium. Apparently, this is the first reported case of rhinosporidiosis in a cat.