Aetiology of tinea of vellus hair and substrate specificity in Microsporum species

Abstract

BackgroundTinea of vellus hair is a dermatophyte infection with or without localised infection of adjacent skin. The epidemiology and pathogenesis of this disorder have insufficiently been established.ObjectivesTo gain insight into the epidemiology and analysis dissection of patterns of vellus hair infection.MethodsA comprehensive examination of our series of cases and existing literature, clinical information was performed. Microsporum species were assayed for levels of keratinase and SUB1‐3 level after different keratin‐induced cultures.ResultsThe infection affects both children and adults, with a male‐to‐female ratio of 1:1.3. The most afflicted areas are the face, neck and upper limbs. Both typical (ringworm‐like) and atypical (tinea incognito) tinea lesions can be observed. The disorder is caused primarily by the zoophilic Microsporum canis (40.39%). Topical antifungal drugs alone are ineffective; mycological cure is achieved in combination with systemic antifungal therapy for 4–8 weeks. In vitro, M. canis exhibited significantly elevated levels of secreted protease and SUB1 and SUB3 transcripts in cat hair cultures. Conversely, the findings of anthropophilic dermatophytes M. audouinii and M. ferrugineum demonstrated the opposite trend, suggesting that there are associations between keratinase activity and expression of SUB1 and SUB3 induced by different keratin substrates among M. canis complex members.ConclusionsThe epidemiological characteristics of tinea of vellus hair help us to understand its transmission patterns and develop effective prevention strategies. There are associations between keratinase activity and expression of SUB1‐3 induced by different substrates, which may explain the host shift and adaptation from pet animals to particular micro‐habitats on the human host.