Confirmed histoplasmosis in an Australian dog

Extradural spinal cord lesion in a dog: first case study of canine neurological histoplasmosis in Italy

A 7-year-old intact male mixed dog was presented with a history of acute and progressive paraparesis. Abnormal clinical signs consisted of non-ambulatory paraparesis, hind limbs hypertonia and severe thoracolumbar pain. Magnetic resonance imaging demonstrated an isointense in T1 and T2 WI epidural lesion, with good contrast enhancement, extending from T-10 to T-13. Laminectomy was carried out to remove the epidural mass. Histological examination revealed a pyogranulomatous lesion characterized by numerous macrophages containing yeast-like Grocott and PAS-positive bodies. Immunohistochemistry and PCR performed on formalin-fixed paraffin-embedded tissue confirmed Histoplasma capsulatum as the causative agent. H. capsulatum has a worldwide distribution in temperate and subtropical climates but its presence as an autochthonous fungus in Europe is now recognized. To the authors' knowledge this is the first report of canine histoplasmosis in Italy with lesion confined to the central nervous system.

Molecular epidemiology of canine histoplasmosis in Japan

A recent case of canine histoplasmosis, the first confirmed case of disseminated infection accompanied by carcinoma in Japan, was diagnosed by clinical characteristics, histopathological examination, chest radiographs, ocular fundoscopy and molecular biological data. The clinical manifestations were not limited to cutaneous symptoms but were referable to disseminated infection, similar to human autochthonous cases. The partial sequences of the internal transcribed spacer (ITS1/2) regions of the ribosomal DNA genes of this and other Japanese canine histoplasmosis strains were 99-100% identical to the sequence AB211551 derived from a human isolate in Thailand, and showed a close relationship to the sequences derived from Japanese autochthonous systemic and cutaneous human cases. The phylogenetic analysis of 97 sequences of the ITS1/2 region disclosed six genotypes. The genotypes derived from Japanese autochthonous human and dog cases belonged to the cluster consisting of Histoplasma capsulatum var. capsulatum and H. capsulatum var. farciminosum sequences, indicating that these varieties might cause not only cutaneous but also systemic histoplasmosis, regardless of their host species. The current status of the 3 varieties of Histoplasma capsulatum according to the host species remains a subject of further investigation.

Interdigital involvement in a case of primary cutaneous canine histoplasmosis in Japan

A 5-year-old male Siberian husky bred outdoor in Tokyo had a swollen paw with interdigital granulomatous lesions in the left hindlimb. The dog had no apparent pulmonary or gastrointestinal involvement. Histopathological analysis of the skin lesions demonstrated yeast-like organisms predominantly within macrophages. Sequence analysis of fungal ribosome RNA gene isolated from a paraffin sample revealed a 100% homology with the teleomorph of Histoplasma capsulatum. The present case may support the concept of primary cutaneous canine histoplasmosis as an endemic phenotype recognized in Japan.

Histoplasmosis in dogs and cats

Histoplasma capsulatum is endemic throughout most of the United States with a high prevalence of infections in the Midwest and South. Histoplasmosis is the second most common systemic fungal disease in cats that may be more susceptible than dogs. Infection occurs by inhalation of conidia from the mycelial phase, which subsequently convert to the yeast form. Histoplasma capsulatum is phagocytized and harbored by cells of the mononuclear phagocyte system. Infection may be subclinical or cause clinical pulmonary granulomatous disease or dissemination. Disseminated disease predominantly affects the liver, spleen, gastrointestinal tract, bone and bone marrow, integument, and eyes. Primary gastrointestinal histoplasmosis also occurs. Clinical signs of histoplasmosis often are nonspecific, including chronic wasting, fever, anorexia, respiratory signs, and lameness. Gastrointestinal signs (eg, diarrhea with hematochezia or melena) are common in dogs. The definitive diagnosis is made by identification of the yeast in tissue samples. Itraconazole is the treatment of choice.

Histoplasmosis in Australia: A report of a case with a review of the literature

Histoplasmosis is a rare but serious fungal infection commonly presenting as mucosal ulceration of the oral cavity. It is increasingly recognized in Australia but the source of infection remains obscure and it is likely to be under-diagnosed. We report a case of chronic mucosal ulceration which failed to fully respond to periodontal therapy. Histology and culture of a gingival biopsy was consistent with histoplasmosis, and the patient responded favourably to treatment with oral itraconazole. Histoplasmosis may present to general dental practitioners as chronic mucosal ulceration and should be considered in the differential diagnosis of such lesions. Diagnosis is best made by culture and histology of biopsy specimens.

Disseminated histoplasmosis in a sea otter (Enhydra lutris)

Disseminated histoplasmosis was diagnosed in a 4.75-year-old, captive female sea otter (Enhydra lutris). At necropsy, the liver was found to be markedly swollen, with many nodules (4-12 mm in diameter). Histologically, macrophages containing numerous intracellular yeast-like organisms were noted in the liver, spleen, lung and kidney. These organisms were labelled immunohistochemically with anti-histoplasma yeast antibody. Ultrastructurally, the yeast-like organisms, 2-4 microm in diameter, were found within membranous structures in the cytoplasm of macrophages. This is the first confirmed report of disseminated histoplasmosis in sea otters.