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[Two cases of canine histoplasmosis in Japan]
1Research Center for Pathogenic Fungi and Microbial Toxicoses, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8673, Japan.
Abstract:
Histoplasmosis is distributed in tropical, subtropical and temperate zones of the world. The disease is one of the imported mycoses in Japan. To date, although more than 30 human and one canine case of histoplasmosis have been reported in Japan, some including that of the canine might have been infected domestically, since the patients have no history of going abroad. The pathogen of histoplasmosis is thus believed to be present in our country. We examined skin biopsies from two dogs in Tokyo and Kumamoto, and found fungal elements 1-2 or 2-4 microEm in diameter in the macrophages. The homology of DNA sequences for the ITS rRNA gene were correspondent to Ajellomyces capsulatus at a rate of more than 97.4%. Therefore, the two dogs were diagnosed as having been infected with Histoplasma capsulatum which is the anamorph of A. capsulatus. Since the dogs had no history of having been outside Japan and had not been brought from an endemic area, they might have been infected domestically. Further epidemiological surveys on canine histoplasmosis may be able to estimate autochthonous human cases in Japan.
Insights
Histoplasmosis, a fungal infection, was diagnosed in two dogs in Japan. DNA analysis confirmed Histoplasma capsulatum, suggesting domestic infection and potential presence of the pathogen in Japan.
Area of Science:
- Veterinary Mycology
- Infectious Diseases
Background:
- Histoplasmosis is a globally distributed fungal infection, considered an imported mycosis in Japan.
- Previous reports include human and canine cases, with some potentially acquired domestically due to lack of travel history.
Observation:
- Skin biopsies from two dogs in Tokyo and Kumamoto revealed fungal elements within macrophages.
- The fungal elements measured 1-2 or 2-4 micrometers in diameter.
Findings:
- DNA sequence homology of the ITS rRNA gene confirmed the pathogen as Ajellomyces capsulatus (anamorph: Histoplasma capsulatum) with >97.4% correspondence.
- The two dogs were diagnosed with histoplasmosis, likely acquired domestically as they had no history of travel abroad or origin from endemic areas.
Implications:
- The findings suggest Histoplasma capsulatum may be endemic in Japan.
- Further epidemiological studies on canine histoplasmosis are warranted to assess the risk of autochthonous human cases.