Paraphyton cookei as a cause of dermatophytosis in calves

Dermatophytosis is a contagious and zoonotic superficial fungal infection affecting various animal species. In cattle production, ringworm has huge sanitary and economic relevance. Although Trichophyton verrucosum is the main etiological agent of bovine dermatophytosis, infections caused by other dermatophyte species may occasionally occur. This study reports an outbreak of dermatophytosis in calves caused by the geophilic dermatophyte Paraphyton cookei in southern Brazil. The outbreak occurred on a beef cattle farm in the state of Rio Grande do Sul during the spring. Of the 360 cattle in the herd, 120 were calves aged 60-90 days, of which 30 exhibited skin lesions characterized by irregular areas of alopecia of varying sizes, accompanied by small crusts and distributed across multiple body regions. Hair and crust samples were collected for mycological examination. Fungal culture produced colonies with macroscopic and microscopic characteristics consistent with P. cookei. The identification was further confirmed by sequencing of the internal transcribed spacer region of rDNA. To the best of our knowledge, this is the first report of dermatophytosis in calves caused by P. cookei. These findings highlight the importance of considering geophilic dermatophytes in the differential diagnosis of bovine dermatophytosis and reinforce the relevance of laboratory identification methods for accurate etiological diagnosis and epidemiological surveillance.