Ringworm in Cattle and Man Caused By Microsporum Canis: Transmission From Dog

Abstract

Dermatophytosis ,caused by many dermatophytic fungi,is an important cutaneous mycotic zoonosis of global significance. Microsporum canis, a zoophilic dermatophyte, was identified as the prime cause of ringworm in two cross-bred, female calves which belonged to a private dairy farm in Gujarat, India. The small, discrete, scaly lesions were observed on the skin of the head and neck of the affected young cattle.The direct examination of the skin scrapings under light microscope showed hyaline,branched ,septate hyphae and arthrospores by potassium hydroxide technique. The fungus was isolated in pure culture from the skin scrapings on Sabouraud dextrose agar and dermatophyte test medium (DTM) .The detailed morphological examination of fungal growth in Narayan stain confirmed the identity as Microsporum canis. The retrospective epidemiology indicated that both the calves contracted the infection from a young male pet dog. In addition, one three- year- old female child in the family also acquired ringworm infection from the diseased dog. The skin scrapings from the calves, dog and child when examined under Wood’s lamp exhibited a bright greenish yellow fluorescence suggesting Microsporum infection. Microsporum canis was also identified in the skin lesions of pet dog and the child by direct microscopy as well cultural isolation on mycological media. Interestingly, the isolates of Microsporum canis from cattle, dog and man did not reveal any difference in their cultural and morphological characteristics. The findings of this investigation indicated that transmission of Microsporum canis from the dog to cattle and man is possible. As animal dermatophytes are communicable to humans, care must be exercised while handling the sick animal or collecting the skin scrapings or applying drug on the skin lesions. It is emphasized that Narayan stain should be widely used in all public health and microbiology laboratories for studying the detailed morphology of fungi which are incriminated in the various clinical disorders of humans as well as animals.