Guinea pigs were cutaneously inoculated with Trichophyton verrucosum var album, that is a common causative fungus of dermatophytosis in cattle. The developmental process of lesions, clinical and histopathological changes and reisolations of the fungi were studied to evaluate the pathogenicity of Trichophyton verrucosum var album in guinea pigs.
Results obtained through the experiments were summarized as follows :
1. The incidence of infection of the clipping group was 13(86%) of 15 animals, and that of the plucking group was 14(93%) of 15 animals. In both of the clipping and plucking groups, visible cutaneoas lesions were developed between 4 and 7 days post inoculation(p.i.). The spreading and the climax stages persisted for 4 to 11 and 6 to 12 days, respectively.
2. In macroscopic observations, formation of various degree of erythemas and scales over the inoclated skin sites were observed in the spreading stage. In the climax stage, exudative changes and dark red crusts were formed as typical circular lesions. In the healing stage, the lesions revealed shedding of crust, alopecia and hair regrowth.
3. In histopathological observations, infiltration of inflammatory cells, hyperplasia, microabscesses and keratinous-hyaloid materials of epidermis were observed in the spreading stage. Hyphal invasion was primarily observed at the level of epidermis and pilosebaceous ducts. In the climax stage, the infected epidermis was thick with severe hyperplasia, hyperkeratosis and acanthosis. The microabscesses with fungal hyphae, folliculitis and hyperplasia of extemal root sheath were observed in the dermis.
The fungal hyphae were observed only in the tissues of hair follicles, that were intemal root sheath, cuticle, the keratinized portions of cortex and medulla
4. In reisolation of the inoculated fungus, all trials for ten animals showed positive cultures until 25 days p.i.. Afterward, the reisolation rates were gradually decreased, showing all negative after 40 days p.i..
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