Occurrence of dermatophytosis in different age groups in a dairy farm around Tehran

Dermatophytosis is a zoonotic skin infection with Trichophyton verrucosum being the main strain responsible for the infection in cattle. The disease occurs mainly in young animals (calves) and it usually spreads between animals through direct contact with a host via infected vegetative structures such as hyphae and spores of the fungus. In March2017, investigations in a dairy farm around Tehran showed that dermatophytosis lesions were present not only in calves but also in heifers and dairy cows. Lesions were usually seen as grayish white crusts in various sizes but they were distinct, limited and thick and the area had hair loss. Pustular lesions protruding as small scabs from the skin surface were seen less frequently. Direct microscopic examination of skin samples were negative for mites but positive for the fungi components such as hyphae and arthroconidiate. The macroscopic properties of fungi strain on Sabouraud dextrose agar medium was as button-like small colonies with white to creamy color, velvet-like surface consistency and a white underside. The microscopic characteristics were long and irregular hyphae with many chained chlamydoconidia which are the diagnostic characteristics of Trichophyton verrucosum. Finally, the infected animals were treated with a 10% solution of sodium iodide at the dose of 1g/14Kg intravenously. This report indicated that Trichophyton verrucosum was responsible for fungal infection at various age groups in the dairy farm therefore it can be concluded that adults as well as young animals are susceptible to the infection and the disease causes damaging effects on growth and the production of milk and meat.