Dermatophytosis due to Trichophyton mentagrophytes in a sheep flock in Italy

AIM: Dermatophytosis in sheep is generally regarded as an uncommon disease. The infection may be under diagnosed or not reported and lambs are considered more susceptible than adults. Its clinical importance is usually mild. Otherwise main consequences regard the long persistence of active lesions, the environmental spreading of fungal elements, the significant economic loss, the difficulties in managing and controlling ringworm as well as the impact on public health when a zoonotic mycotic species is involved. Trichophyton verrucosum represents the mainly involved fungal species (Scott, 1975 Onderst J Vet Res 42, 49-52.; Sargison and others, 2002 Vet Rec 150, 755-756). Microsporum canis was reported in some outbreaks of ovine ringworm (Roberts and Kepp, 1965 Sabouraudia 4, 96-97; Sharp and others, 1993 Vet Rec 132, 388) and to a lesser extent Microsporum gypseum (Hullinger and others, 1999 Vet Dermatol 10, 73-76). Infections caused by Trichophyton mentagrophytes have been less frequently reported and, being the records obtained from epidemiological surveys only (Pier and others, 1994 J Med Vet Mycol 32, 133-150; Khosravi and Mahmoudi, 2003 Mycoses 6, 222-225) clinical signs have not been described. In this report the occurrence and the clinical resolution of ringworm associated with T. mentagrophytes, in a sheep flock in Italy are described. MATERIALS AND METHODS: The outbreak occurred in a Zerasca sheep flock, consisting of about 200 animals, maintained in Northern Tuscany. Eighteen ewes from a group of 60 adults exhibited several circular facial lesions, with a diameter up to 6 cm. The lesions were alopecic and erythematous, sometimes covered by thick crusts. Skin scrapings were collected from affected sheep to detect Sarcoptes scabiei. The hair specimens were seeded onto Sabouraud Dextrose agar added with 0.05% cicloheximide and plates were incubated at 25°C for ten days. The plates were checked for mycotic growth from the day 4 post-inoculation. RESULTS: All cultured samples yielded a pure growth of T. mentagrophytes var. mentagrophytes, identifiable by macro- and microscopic features. Skin scraping failed to detect mites. Considered that antimycotic drugs licensed for food producing sheep are not present within the European Community, an unconventional treatment by using herbal remedies was selected. Essential oils (EOs) from Origanum vulgare and Thymus serpillum were selected for their strong antimycotic activity (Janssen and others 1988, Pharm Week Sci Ed 10, 277-280) due to the high amount of thymol and carvacrol, respectively. Rosmarinus officinalis was added considering that, even if its antifungal action is lower, it has marked antiinflammatory properties. The chemical composition of employed EOs is described elsewhere (Pistelli and others, Open Mycol J in press). The animals were topically administered a mixture composed by O. vulgare (5%), R. officinalis (5%) and T. serpillum (2%) in sweet almond (Prunus dulcis) oil as previously reported (Pisseri and others, 2009 Phytomedicine 16, 1056-1058) twice a day for 15 days directly on affected areas. After treatment, skin lesions gradually regressed and hair re-growth started. Adverse effects were never noticed. Control cultures performed two weeks after the end of treatment were all negative, and the recovery was definitive. CONCLUSIONS: Overcrowded housing, bad conditions of bedding and poor ventilation of shelters where sheep congregated during the winter season could represent predisposing factors. The zoonotic character of disease, the wide spread of infection to other animals and the risk for environmental contamination make the treatment strongly advisable. At the best of our knowledge, this is the first clinical description of ringworm associated with T. mentagrophytes in sheep. The early identification of the causative agent and the treatment with EOs were useful to prevent the spread of infection from the face to other parts of the body, and to achieve a successful outcome.