Isolation of Dermatophytes from the Hair Coat of Healthy Persian Cats without Skin Lesions from Commercial Catteries Located in São Paulo Metropolitan Area, Brazil

Abstract

Background: The study of the epidemiological chain of dermatophytosis, particularly those related to zoophilic fungi, is extremely important because of its frequent occurrence, the high infectivity of the agent, and its anthropozoonotic character. In all latitudes, asymptomatic cats are considered the main reservoirs and sources of dermatophyte infection. The study aimed to characterize the frequency of dermatophyte infection and the potential risk of microsporic infection to the owners and to possible buyers of apparently healthy Persian cats from commercial catteries of São Paulo, Brazil.Materials, Methods & Results: Fur samples were obtained from 61 clinically healthy Persian cats, which were devoid of typical cutaneous lesions and had negative results in Wood’s lamp examination. The average age of the cats was 37.7 months; 18 (29.5%) of them were males and 43 (70.5%) were females. The cats were from commercial catteries located in the metropolitan region of São Paulo state capital. Samples were obtained using the technique of Mariat & Adam using a square (25 cm2) of sterile carpet rubbed across the surface of the hair-coat and skin. People who had close contact with the animals were asked whether they had had typical ringworm lesions in the recent past or at the time of sample collection. The material collected was pressed onto Petri dishes containing agar supplemented with chloramphenicol and cycloheximide. The Petri dishes were handled under sterile conditions and incubated at 25°C for up to 21 days. There was evident fungal growth in 83.6% of the samples, and the only dermatophyte isolated was Microsporum canis. The results were analyzed using the chi-square test in order to verify possible associations between variables (sex and age range) and the frequency of dermatophyte infection in dermatologically healthy animals. However, there was no statistical difference regarding sexual predisposition (P value = 0.139) and age (P value = 0.224) regarding the asymptomatic dermatophyte carriers. Of the 18 people who had close contact with infected cats, eight (44.4%) claimed to have presented with typical tinea corporis lesions in the past and three (16.7%) said that they had such skin lesions at the time of harvest of the cat fur. There were no people who claimed to have been in contact with other species.Discussion: In Brazil, fungal infections represent up to 8.7% of skin diseases in children, and tinea capitis caused by Microsporum canis is the most common superficial mycosis in this age group. Its interspecies transmission has been reported for decades. Approximately 50% of individuals exposed to symptomatic or asymptomatic cats acquire the disease. In up to 70% of families with infected cats, at least one family member may develop the disease. Among domestic cats, the Persian breed is most often cited as prone to spreading dermatophytes. In the study, there was fungal growth in 83.6% of the samples, and only M. canis was isolated. Among the people who had contact with the cats, 44.4% and 16.7% had typical tinea corporis lesions in the past and at the time of the interview, respectively. However, it is speculated that the rate of infection may have been higher in the humans in contact with these cats, since there may have been some hesitation and fear by the people interviewed in reporting the occurrence of characteristic skin lesions, either as a way of preserving the cattery reputation, or to spare the embarrassment in declaring oneself as infected, which is sometimes viewed negatively. The results demonstrate the potential infectivity, pathogenicity, and risk of microsporic infection in buyers of apparently healthy cats from commercial catteries located in the metropolitan region of São Paulo.