OTHER DERMATOPHYTE INFECTIONS
CLAUDIA CAFARCHIA
Department of Veterinary Public Health, University of Bari, Valenzano (Bari), Italy
Dermatophytoses (also referred to as ringworm) are superficial, cutaneous mycoses caused by filamentous fungi — the dermatophytes — which invade keratinized tissues (i.e.
skin, hair and nails) of humans and animals, causing mild to severe, localized and/or diffuse infections. Dermatophytes are grouped into anthropophilic, zoophilic and geophilic species according to their habitat. Zoophilic dermatophytes infect both animals and humans, whereas anthropophilic dermatophytes mainly infect humans. Geophilic dermatophytes can induce both animal and human infections. Animal dermatophytoses are caused by fungi of the genera Microsporum and Trichophyton. Among these, Microsporum canis and species belonging to Trichophyton mentagrophytes complex are zoophilic species pathogenic to humans. In wild animals, dermatophyte fungi have been recovered mainly from healthy animals, including rodents, insectivores, lago- morphs, foxes ( Vulpes vulpes), wild boar (Sus scrofa), wolves (Canis lupus), polecats (Mustelaputorius) and badgers (Meles meles), and have only occasionally been reported in diseased animals (i.e. Eastern cottontail rabbit (Sylvilagus floridanus) and chamois (Rupicapra rupicapraff22123. Microsporum canis and T mentagrophytes complex species are the most frequently retrieved species, followed by geophilic dermatophytes such as Microsporum cookie, M. gypseum, Trichophyton ajelloi and T terrestre. Dermatophyte infection is acquired by contact between healthy and diseased animals but also from the environment. Generally the clinical signs include mild to severe alopecia associated with erythema. Hairs, if present, are easily epilated. Laboratory diagnosis consists of direct microscopic examination of the clinical specimen followed by in vitro culture techniques. On direct microscopic examination, chains of spherical, translucent spores (arthro- conidia), with a diameter ranging from 2 to 18 μm, can be observed using 10% potassium hydroxide. Colonies grown onto Sabouraud dextrose agar supplemented with chloramphenicol 0.05 g/l and cycloheximide 0.5 g/l are identified to species based on their morphology and the microscopic characteristics of the hyphae, macroconidia and microconidia.Mammalian dermatophytosis usually resolves spontaneously (self-cure) within 1 to 4 months, but the contagious and zoonotic nature of this disease makes treatment mandatory for companion animals. Miconazole, chlorhexidine, lime sulphur dips and enilconazole are useful topical treatments. Griseofulvin, ketoconazole and itraconazole are the most frequently used therapeutic agents for the systemic treatment of dermatophytosis. The treatment should be continued for 2 to 4 weeks after clinical resolution, and until two negative cultures have been obtained. For environmental decontamination, hypochlorite bleach and enil- conazole environmental spray are frequently employed.