A case in Europe of feline histoplasmosis apparently limited to the skin

Animal Histoplasmosis in Europe: Review of the Literature and Molecular Typing of the Etiological Agents

Histoplasmosis has been previously diagnosed in animals from Europe. The aim of this study is to review the literature on these reports, to analyze cases diagnosed at our laboratory (2000–2022) and to improve molecular typing of Histoplasma capsulatum directly from tissue to study the molecular epidemiology of Histoplasma capsulatum causing animal infections in Europe. Including 15 cases studied in our laboratory, we identified 39 cases of animal histoplasmosis between 1968 and 2022. They were diagnosed mostly in superficial tissue biopsies from cats and badgers from Central Europe. Using phylogenetic analyses of six partial genes, we were able to classify eight of the etiological agents as belonging to a highly supported lineage within the Eurasian clade. This study confirms the occurrence of autochthonous histoplasmosis in animals in Central Europe and proposes the addition of new loci to the MLST scheme to study the molecular epidemiology of histoplasmosis using either formalin-fixed paraffin-embedded tissue and fresh or cadaveric biopsies.

Histoplasmosis Diagnosed in Europe and Israel: A Case Report and Systematic Review of the Literature from 2005 to 2020

Human histoplasmosis is a mycosis caused by two distinct varieties of a dimorphic fungus: Histoplasma capsulatum var. capsulatum and H. capsulatum var. duboisii. In Europe, it is usually imported by migrants and travellers, although there have been some autochthonous cases, especially in Italy; however, most European physicians are unfamiliar with its clinical and pathological picture, particularly among immunocompromised patients without HIV infection. This systematic review of all the cases of histoplasmosis reported in Europe and Israel between 2005 and 2020 identified 728 cases diagnosed in 17 European countries and Israel described in 133 articles. The vast majority were imported (mainly from Central and South America), but there were also seven autochthonous cases (six in Europe and one in Israel). The patients were prevalently males (60.4%), and their ages ranged from 2 to 86 years. The time between leaving an endemic region and the diagnosis of histoplasmosis varied from a few weeks to more than 40 years. Progressive disseminated histoplasmosis was the most frequent clinical picture among people living with HIV infection (89.5%) or a different immunocompromising condition (57.1%), but it was also recorded in 6.2% of immunocompetent patients. Twenty-eight cases were caused by Histoplasma duboisii. Immunocompromised patients without HIV infection had the worst outcomes, with a mortality rate of 32%.

Detection of Histoplasma DNA from Tissue Blocks by a Specific and a Broad-Range Real-Time PCR: Tools to Elucidate the Epidemiology of Histoplasmosis

Lack of sensitive diagnostic tests impairs the understanding of the epidemiology of histoplasmosis, a disease whose burden is estimated to be largely underrated. Broad-range PCRs have been applied to identify fungal agents from pathology blocks, but sensitivity is variable. In this study, we compared the results of a specific Histoplasma qPCR (H. qPCR) with the results of a broad-range qPCR (28S qPCR) on formalin-fixed, paraffin-embedded (FFPE) tissue specimens from patients with proven fungal infections (n = 67), histologically suggestive of histoplasmosis (n = 36) and other mycoses (n = 31). The clinical sensitivity for histoplasmosis of the H. qPCR and the 28S qPCR was 94% and 48.5%, respectively. Samples suggestive for other fungal infections were negative with the H. qPCR. The 28S qPCR did not amplify DNA of Histoplasma in FFPE in these samples, but could amplify DNA of Emergomyces (n = 1) and Paracoccidioides (n = 2) in three samples suggestive for histoplasmosis but negative in the H. qPCR. In conclusion, amplification of Histoplasma DNA from FFPE samples is more sensitive with the H. qPCR than with the 28S qPCR. However, the 28S qPCR identified DNA of other fungi in H. qPCR-negative samples presenting like histoplasmosis, suggesting that the combination of both assays may improve the diagnosis.

Occurrence of various pathogenic and opportunistic fungi in skin diseases of domestic animals: a retrospective study

Background

Fungal infection of animals or humans are common all over the world. Some of microorganisms like fungi, exist on the skin and can be transmitted onto other individuals, other animal species or even humans and cause skin infections. Moreover, they can be the causative agents of severe generalized infections especially in immunocompromised individuals. The study aimed to evaluate the most frequent etiological agents of skin diseases and to compare the prevalence of animal fungal infections in Poland, and to discuss the possibility of transmission to humans in Poland.

Results

The obtained results are culture based. The fungi most frequently isolated from group of animals with skin lesions were Malassezia pachydermatis (29.14%), and Candida yeasts (27.07%), and dermatophytes (23.5%), including Microsporum canis as majority of them (59.25%), and Trichophyton genus (40.7%), most of them T. mentagrophytes, while Malassezia pachydermatis represented (80%) of isolates in animals with otitis externa. In over 19% of positive fungal cultures obtained from external ear canals Candida yeasts, mainly C. albicans, were identified.

Conclusions

Dermatomycoses in companion animals are caused by both, mycelial fungi and yeasts. Most frequently isolated were Malassezia pachydermatis and Candida spp. Dermatophytes (Trichophyton, Microsporum), were also cultured, but the total number of these isolates seems to decrease. We have not found Cryptococcus neoformans in tested clinical samples.

Doenças micóticas em gatos no Rio Grande do Sul

RESUMO: As enfermidades fúngicas são diagnósticos diferenciais de diversas morbidades de caráter infeccioso, degenerativo ou proliferativo neoplásico, principalmente em gatos, que é a espécie mais suscetível a estas. Este trabalho descreve os achados anatomopatológicos de doenças fúngicas em gatos no período de janeiro de 2005 a dezembro de 2015 pelo SPV-UFRGS. Foram revisados 1.274 protocolos de necropsia e encontrou-se 17 casos de micoses, correspondendo a 1,33% dos diagnósticos. Quanto às amostras provenientes de biopsias, foram verificados 2.615 protocolos e detectou-se 59 casos de doenças fúngicas, totalizando 2,25% dos diagnósticos, sendo revisados seus achados macroscópicos, microscópicos, colorações especiais e cultivo micológico. O principal diagnóstico encontrado foi esporotricose com 34 casos de biópsia e cinco de necropsia. Criptococose obteve seis diagnósticos na necropsia e 13 na biópsia. O pseudomicetoma dermatofítico possui cinco casos de biópsia e dois de necropsia. Histoplasmose obteve um diagnóstico na necropsia e dois na biópsia. Aspergilose teve dois casos diagnosticados na necropsia. Candidíase e feo-hifomicose obtiveram um caso cada. Em quatro ocasiões, não se pode identificar o agente envolvido na lesão e foram classificados conforme a alteração morfológica em: dermatite fúngica, enterite fúngica, rinite micótica e dermatite e osteomielite fúngica. Através deste trabalho, pode-se identificar que a esporotricose foi o diagnóstico de doença fúngica mais frequente em felinos, seguido da criptococose e pseudomicetoma dermatofítico.

Utility of antigen testing for the diagnosis of ocular histoplasmosis in four cats: a case series and literature review

Case series summary This case series describes the clinical utility of antigen testing for the diagnosis of feline ocular histoplasmosis. Four cats with suspected (n = 2) or confirmed (n = 2) ocular histoplasmosis are described: three from Oklahoma and one from California. In one case, serial urine antigen tests, as well as a serum antigen test for Histoplasma capsulatum, were negative; however, light microscopy identified microorganisms consistent with H capsulatum in ocular tissues at necropsy. In a further two cats with recurrent ocular histoplasmosis following long-term systemic antifungal therapy, Histoplasma species urine antigen concentrations were negative, but both cats improved clinically following systemic antifungal therapy and remained in apparent clinical remission after treatment cessation (9-16 months). The final cat displayed profound bilateral endophthalmitis; however, Histoplasma species antigen testing of vitreous humor and subretinal fluid from the left eye was negative. Intralesional organisms were detected on histopathology of both eyes, and H capsulatum was subsequently isolated and sequenced from tissue of one eye. Relevance and novel information These cases highlight the potential difficulty in definitively diagnosing ocular histoplasmosis in cats when conducting antigen testing of serum, urine and even ocular fluids. Although antigen testing has previously proven useful in the diagnosis of disseminated feline histoplasmosis, it may not be adequate in cats with only ocular signs.

Feline cutaneous histoplasmosis: The first case report from Thailand

A 2-year-old, neutered female domestic shorthaired cat presented with a history of multiple papules and nodules on pinnae, nodules on the nose, and chronic wound at the lateral surface of left radial area for four months. Skin biopsy demonstrated moderate numbers of small, oval-to-round, single-walled yeasts inside the macrophages. In addition, PCR confirmed the sequence of Histoplasma capsulatum. This is the first case report of feline cutaneous histoplasmosis in Thailand.

Cutaneous blastomycosis and dermatophytic pseudomycetoma in a Persian cat from Bangkok, Thailand

This is a case report of concurrent of blastomycosis and pseudomycetoma in a 3 year-old Persian cat from Bangkok, Thailand. Histopathology from antemortem and postmortem samples revealed blastomycosis and dermatophyte pseudomycetoma. The PCR analysis of the formalin-embedded tissue of antemortem sample confirmed that blastomycosis was caused by Blastomyces dermatitidis. Dermatophyte infection was caused by Microsporum canis. According to the author's knowledge, this is the first case of Blastomyces dermatitidis and dermatophyte pseudomycetoma in South-East Asia.

Worldwide Phylogenetic Distributions and Population Dynamics of the Genus Histoplasma

Background

Histoplasma capsulatum comprises a worldwide complex of saprobiotic fungi mainly found in nitrogen/phosphate (often bird guano) enriched soils. The microconidia of Histoplasma species may be inhaled by mammalian hosts, and is followed by a rapid conversion to yeast that can persist in host tissues causing histoplasmosis, a deep pulmonary/systemic mycosis. Histoplasma capsulatum sensu lato is a complex of at least eight clades geographically distributed as follows: Australia, Netherlands, Eurasia, North American classes 1 and 2 (NAm 1 and NAm 2), Latin American groups A and B (LAm A and LAm B) and Africa. With the exception of the Eurasian cluster, those clades are considered phylogenetic species.

Methodology/Principal Findings

Increased Histoplasma sampling (n = 234) resulted in the revision of the phylogenetic distribution and population structure using 1,563 aligned nucleotides from four protein-coding regions. The LAm B clade appears to be divided into at least two highly supported clades, which are geographically restricted to either Colombia/Argentina or Brazil respectively. Moreover, a complex population genetic structure was identified within LAm A clade supporting multiple monophylogenetic species, which could be driven by rapid host or environmental adaptation (~0.5 MYA). We found two divergent clades, which include Latin American isolates (newly named as LAm A1 and LAm A2), harboring a cryptic cluster in association with bats.

Conclusions/Significance

At least six new phylogenetic species are proposed in the Histoplasma species complex supported by different phylogenetic and population genetics methods, comprising LAm A1, LAm A2, LAm B1, LAm B2, RJ and BAC-1 phylogenetic species. The genetic isolation of Histoplasma could be a result of differential dispersion potential of naturally infected bats and other mammals. In addition, the present study guides isolate selection for future population genomics and genome wide association studies in this important pathogen complex.

Histoplasmosis is a potentially severe fungal disease of mammals caused by Histoplasma capsulatum. The highest incidence of the disease is reported on the American continent, and approximately 30% of HIV and histoplasmosis co-infections are fatal. Previous studies have suggested at least 7 phylogenetic species within H. capsulatum, however by increasing taxon sampling and using different phylogenetic and population genetic methods, we detect at least 5 additional phylogenetic species within Latin America (LAm A1, LAm A2, LAm B1, LAm B2, RJ and BAC-1). These phylogenetic species are nested in the former LAm A clade. We found evidence that bats may be a cause of speciation in Histoplasma, as well-supported monophyletic clades were found in association with different species of bats. The radiation of the Latin American H. capsulatum species took a place around 5 million years ago, which is consistent with the radiation and diversification of bat species. Previous phylogenetic distribution of Histoplasma is upheld and strong support is indicated for the species delineation and evolution of this important pathogen.