Multiple cases of feline dermatophytosis due to Microsporum canis transmitted to their owners

Introduction

Dermatophytes are usually the most frequent causes of dermatological problems in domestic animals (Betancourt et al., 2009; da Costa et al., 2013). Dermatophytosis is a common infection that involves keratinized tissues including skin, nails and hair with inflammatory reaction in the host, characterized by multifocal alopecia, scaling and circular lesions. Animals serve as reservoirs of the zoophilic dermatophytes,and their infections have considerable zoonoticimportance (da Costa et al., 2013; Rezaei-Matehkolaei et al., 2012; Hermoso de Mendoza et al., 2010; Cabañes, 2000).

Zoophilic species such as Microsporum canis, Ttichophyton mentagrophytes var. mentagrophytes and T. verrucosum are significant causal agents of human ringworm in many areas of the world. The incidence of dermatophytosis varies according to climate and natural reservoirs (Cabañes, 2000). However, the pattern of the species of dermatophytes involved in dermatophytosis may be different in similar geographical conditions, both in humans and animals.

Epidemiological studies on the isolation of dermatophytes from dogs and cats with suspected lesions of dermatophytosis have been reported by various researchers (Lewis et al., 1991; Sparkes et al., 1993).

Lesions in cats appear primarily on the face and paws. In cats with suspected lesions of dermatophytosis the prevalence of dermatophytes is usually higher than in dogs, and it is usually more than 20% (Sparkes et al., 1993; Lewis et al., 1991). Cats are accepted as the principal reservoir for M. canis. This species is the most common dermatophyte isolated from cats, with percentages of isolation higher than 90% from animals with suspected lesions of dermatophytosis (Sakae et al., 2011; DeBoer et al., 2003). Other dermatophytes less commonly isolated from cats are T. mentagrophytes and M. gypseum. These three species comprise approximately 98% of the isolated dermatophytes from cats in the above cited epidemiological studies (Sparkes et al., 1993).

The present study was designed to investigate the prevalence of M. canis that transmitted from cats cohabiting with owners to their owners diagnosed with dermatophytosis.In addition, this study evaluated the age, sex, breed, habitat and season as potential risk factors associated with the isolation of M. canis from cat owners that involved with dermatophytosis.

Materials and Methods

From January 2010 to January 2013, thirty cases of cats and their owners with dermatophytosis lesions were examined. All cats included in the study were from the Tehran and East Azerbaijan providences (Iran) and were examined and sampled at private veterinary facilities, or at the Faculty of Veterinary Medicine (University of Tabriz). Animals lived in urban areas (center of a large city) where they were not allowed to range freely. Some of these cats lived together.

At the time of examination and sampling, the animals were evaluated for any predisposing factor for dermatophytosis. Owners of cats selected for sampling had dermatophytic lesions. They were questioned on their own and their family members history of dermatophytosis diagnosed by fungal culture.  Epidemiological data were collected, asthe age, sex, breed and habitat of the animals were recorded. In order to evaluate seasonal trends in dermatophyte infections, the sampling period was recorded. Also fifteen human infected with M. canis that referred to medical laboratories were questioned for owning cats and their dermatophytic lesions. 

Hair and skin samples were collected from cases using the scraping technique.  After specimen collection, the scraped skin and hair samples were placed in original package and transported as soon as possible to the laboratory for direct examination and fungal culture. Direct examination carried out with 10%KOH and Lacto phenol blue. Fungal cultures were performed by Sabouraud’s dextrose agar with chloramphenicol (0.5%) and actidione and incubated at 25˚C for 15 days. Colonies grown in the medium were identified based on their morphology and microscopic characteristic of the hyphae, macroconidia and microconidia (de Hoog et al., 2000, Rezaei-Matehkolaei et al., 2012).

Results

The typical clinical sign of M. canis infection in cats is ringworm or regular and circular alopecia, with hair fracture, desquamation, sometimes an erythematous margin and central healing. In this study we observed various types of presentation in cats as some lesions to be quite small but some have a diameter of 5-7 cm.  

Lesions were single or multiple, mostly localized on the face and head. However they were found on any part of the body, including the distal parts of the legs and the tail. Young cats, in particular, displayed lesions localized to the bridge of the nose at first extending to the temples, the external side of the pinnae and auricular margins. In some cases multiple lesions grown together all over the body. All cats have variable pruritus without fever and loss appetite.

Frequently, in clarified samples with KOH and LCB arthrospores are seen surrounding and within the hair shaft. In some cases fungal hyphae and arthrospores in scraped skin were seen. A flat, white, fluffy, spreading colony developed within 7 to 15 days. A characteristic deep yellow pigment may be observed on the reverse side of a colony on Sabouraud’s dextrose agar or DTM. On DTM, the media should change from amber to red, concurrent with growth. Observation of a Lacto phenol Blue mount will reveal septate hyphae and numerous, fusiform, thick-walled macroconidia that usually contain more than six compartments. A few club-shaped, smooth-walled microconidia also may be present, as well as round-shaped chlamydoconidia. Among M. canis colonies isolated from cats, 90% have good sporulation and produce abundant macroconodia whereas 10% of isolates was poor in macroconodia production. On the other hand, 21% M. canis isolated from human cases in this study were poor in sporulation on mycological media.    

In this study cats and their owners with dermatophytic lesions were contemporarily examined. Among 30 cats with dermatophytosis, 53.3% were female and 47.7% were male. They ranged in age from 2 months to 7 years. The affected sites were the head and face (n=20), leg and trunk (n=13); exposed sites were those most often affected (Fig 1). Single and multiple eruptions were observed in 20 and 10 cats, respectively. In the owners, the disease type was tinea corporis in 20 patients, and tinea capitis in 3 cases (all of them were child men) (Fig 2). No combination of tinea corporis and tinea capitis were observed. The disease showed familial onset in 2 patients, including 2 sibling pairs (Table 1). In most of cases, the lesions were moderate to severely inflammatory. There were 8 patients that their lesions were limited with low inflammatory reaction.  The human patients were treated with topical antifungal agents, oral Itraconazole or terbinafine for 2-14 weeks, combined with topical antifungal therapy. However, two patients had recurrent infection after discontinuation of antifungal usage. These patients were treated with combination therapy. No resistance to antifungal treatment was found, however one patient developed dermatophytic lesions after ketoconazole prescription. After shifting the treatment from antifungal to Itraconazole agent, the lesions were disappeared. We did not find any predisposing factors except encountering and dealing with infected cats (Table 1).