Zoonotic infections with dermatophyte fungi

Abstract

Dermatophytes are highly specialized pathogenic fungi which are the most common agents of superficial mycoses. These fungi grow exclusively in the stratum corneum, nails or hair utilising them as sole nitrogen and carbon sources. Dermatophyte species are recognized and classified as antropophilic, zoophilic, or geophilic, depending on their major reservoir in nature (humans, animals, and soil, respectively). Zoophilic dermatophytes may result in zoonoses when humans are exposed to these organisms and dermatophytosis is considered to be one of the most common zoonotic diseases. The majority of zoonotic dermatophytoses are caused by four species: Microsporum canis (usually derived from pet animals, particularly cats and dogs), Trichophyton verrucosum (usually derived from cattle), Arthroderma vanbreuseghemii (usually derived from cats and dogs) and Arthroderma benhamiae (usually derived from guinea-pigs). Infection results most often from direct contact with an infected animal, but may be also acquired indirectly through contact with a contaminated environment. While clinical disease is rarely serious, the lesions can result in disfigurement and pain. Diagnosis is based on history, clinical appearance and diagnostic procedures, e.g. direct microscopic examination of scales, hair or nail and fungal culture. Specific treatment is generally required to resolve lesions, and this may be prolonged depending on the fungal species and the host status. Identifying animals as the source of infection for people can help in the prevention of recurrence or new infections, especially in children, by adequately treating affected pets and their environments. Immunoprophylaxis is an attractive means of controlling infection in animals, and the development and widespread use of efficacious T. verrucosum vaccines in certain countries has already proved valuable in the management of cattle ringworm.