Molecular epidemiology of canine histoplasmosis in Japan

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.

Development and Evaluation of a Molecular Diagnostic Method for Rapid Detection of Histoplasma capsulatum var. farciminosum, the Causative Agent of Epizootic Lymphangitis, in Equine Clinical Samples

“…capsulatum var. farciminosum, with clinical cases being reported in dogs (23), badgers (24), and even humans (25). The phylogeny of Histoplasma spp.…”

“…The phylogeny of Histoplasma spp. has been examined using a range of different gene loci (22, 23, 25–30). As has been frequently reported for fungi, sequence variation in the internal transcribed spacer (ITS) region of the rRNA operon provides a resolving power sufficient to discriminate between closely related species and variants and can contribute to the design of specific PCR-based detection protocols (25, 27, 31, 32).…”

First Case Report of Histoplasmosis in a Cat in Japan

“…Seven cases of canine histoplasmosis have been reported in Japan [12,17,18,20,22]. In addition, Murata et al have compared canine cases with worldwide human and equine cases with respect to partial sequences on the internal transcribed spacer (ITS1/ 2) regions of the ribosomal DNA genes [17]. This phylogenetic analysis performed by nested polymerase chain reaction (nested PCR) and sequence analysis have revealed that these canine cases in Japan were closely related to the Asian autochthonous human cases.…”

“…Recently, however, autochthonous cases have been reported in humans [13]. Seven cases of canine histoplasmosis have been reported in Japan [12,17,18,20,22]. In addition, Murata et al have compared canine cases with worldwide human and equine cases with respect to partial sequences on the internal transcribed spacer (ITS1/ 2) regions of the ribosomal DNA genes [17].…”

“…The method of DNA extraction, the primer sequences specific to H. capsulatum, and the method of nested PCR were selected according to previously published reports [14,17]. The primer sequences for nested PCR were as follows: the primers for the first PCR were ITS-5 (5'-GGAAG-TAAAAGTCGTAACAAGG-3') and ITS-4 (5'-TCCTC-CGCTTATTGATATGC-3') , and those for the second PCR were HcAF (5'-CACGCCGTGGGGGGCTGGGAGCCT-3') and HcCR (5'-ATGGTGGGCRGGAGCCGGCC-3') with a complementary sequence of 5'-GGCCGGCTC-CYGCCCACCAT-3'.…”