ABSTRACT
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.
Subject(s)
Dog Diseases/microbiology , Histoplasma/classification , Histoplasma/isolation & purification , Histoplasmosis/veterinary , Molecular Epidemiology , Animals , Choroiditis/pathology , DNA, Fungal/chemistry , DNA, Fungal/genetics , DNA, Ribosomal Spacer/chemistry , DNA, Ribosomal Spacer/genetics , Dog Diseases/diagnosis , Dog Diseases/epidemiology , Dog Diseases/pathology , Dogs , Extremities/pathology , Female , Fundus Oculi , Histocytochemistry , Histoplasma/genetics , Histoplasmosis/epidemiology , Histoplasmosis/microbiology , Histoplasmosis/pathology , Japan/epidemiology , Lung/diagnostic imaging , Lung/pathology , Male , Molecular Sequence Data , Ophthalmoscopy , Phylogeny , Radiography , Sequence Analysis, DNA , Sequence Homology, Nucleic Acid , Skin/pathologyABSTRACT
The lesions of histoplasmosis in dogs in Japan differ from those in dogs in North America. Affected dogs in Japan have had multiple granulomatous or ulcerated foci in skin or gingiva and have not had pulmonary or gastrointestinal lesions. The present report introduces a polymerase chain reaction (PCR) diagnosis of canine histoplasmosis and the characteristic of disease in Japan. The surgically removed skin ulcerate samples from a 5-years-old female Shiba-inu native to Japan without traveling out of the country were evaluated. Tissue samples had many yeast-like organisms in the macrophages. DNA was extracted from paraffin-embedded tissue samples. A nested PCR technique was applied. The detected sequence of the internal transcribed spacer of ribosomal RNA gene had 99.7% in homology with Ajellomyces capsulatus (the teleomorph of Histoplasma capsulatum). Clinical manifestations, historical background of equine epizootic lymphangitis in Japan, and a human autochthonous case of histoplasmosis farciminosi indicated that this dog might have been infected with H. capsulatum var. farciminosum as a heteroecism.
