Treatment of Microsporum canis ringworm in a cat colony

Abstract— The treatment and control measures used during an outbreak of feline ringworm caused by Microsporum canis are described. During the outbreak the presence of the dermatophyte on the coats of clinically normal cats was demonstrated by the use of Mackenzie's brush technique. This method of examination is suggested as being the most effective and rapid means of ensuring that dermatophyte infection is not introduced into a colony by new cats. Résumé— L'auteur décrit le traitement et les mesures antiparasitaires appliqués à l'occasion d'une épizootie de teigne féline, provoquée par Microsporum canis. La préence du dermatophyte sur le poil de chats cliniquement normaux a été décelée par la technique de la brosse Mackenzie, méthode particulièrement rapide et efficace, propre à éviter la contamination d'une colonie de chats par des dermatophytes importés de l'extérieur. Zusammenfassung— Die Behandlung und die Kontrollmassnahmen während eines Ausbruchs von durch Microsporum caniJ verursachter Katzenringwurmkrankheit werden beschrieben. Wahrend der Krankheit wde das Vorhandensein der Dermatophyten in den Pelzen klinisch normaler Katzen durch Anwendung der Mackenzieschen Pinselmethode demonstriert. Diese Untersuchungs methode wird ah wirksamste und schnellste vorgeschlagen, die gewährleistet, dass die Dermatophyten nicht durch neue Katzen in eine Kolonie eingeschleppt werden.     

Disinfectants in the control of small animal ringworm due to Microsporum canis

Twelve disinfectant products or compounds were evaluated for their ability to kill Microsporum canis harvested from naturally infected material. The disinfectants were diluted to the concentration recommended for the disinfection of clean surfaces and the potency of each substance was determined by the degree to which it could be further diluted before losing its fungicidal action. Hypochlorite, benzalkonium chloride and glutaraldehyde based compounds were the most effective agents and phenolics, alcohol and anionic detergents were inadequate. Urea (10 mM) did not adversely affect the potency of any of the compounds.     

Drug efficacy of terbinafine hydrochloride (Lamisil) during oral treatment of cats,experimentally infected with Microsporum canis

Cats represent a primary source of Microsporum canis infections in humans. Terbinafine hydrochloride (Lamisil) is commonly used in the treatment of microsporosis in humans as its fungicidal action permits short periods of treatment. The aim of the present study was to estimate the efficacy of the drug in cats. Nine cats were experimentally infected with M. canis and treated with terbinafine hydrochloride at a dose of 10-20 mg/kg (once daily, SID; low-dose group, LDG). Another nine cats were similarly infected and treated with 30-40 mg/kg SID (high-dose group, HDG) and a further nine cats were also infected and left untreated (control group, CG). The general condition of the cats was observed daily and their clinical symptoms evaluated weekly. The cats recovery was monitored using the Wood's lamp illumination test and microscopic and fungal culture examinations. The general condition of the cats during the study was good. The cure rates of the LDG were not significantly different from the CG at any period during the treatment. However, the HDG cure rates differed significantly from the other two groups. After 109 days of treatment, when all nine cats of the HDG were healed, seven cats of the LDG and all the cats in the CG were still M. canis-positive. This study shows that dosages of 10-20 mg/kg SID of terbinafine hydrochloride are not sufficient to terminate an experimental M. canis infection in cats within an acceptable period of time. Terbinafine hydrochloride can be used to treat dermatophytosis in cats, but a higher dosage, 30-40 mg/kg SID, should be used to achieve a cure.     

Effects of lufenuron treatment in cats on the establishment and course of Microsporum canis infection following exposure to infected cats

OBJECTIVE: To determine effects of lufenuron treatment in cats on the establishment and course of Microsporum canis infection following exposure to infected cats. DESIGN: Experimental trial. ANIMALS: 24 healthy juvenile domestic shorthair cats. PROCEDURE: 8 cats were given lufenuron PO (133 mg/cat/mo, equivalent to a dose of 100 to 130 mg/kg [45 to 59 mg/lb] at the beginning of the study and 25 to 35 mg/kg [11 to 16 mg/lb] at the end of the study), and 8 were given lufenuron SC (40 mg every 6 months). The remaining 8 were used as untreated control cats. After 4 months, cats were challenged by the introduction of cats with mild, experimentally induced M canis infection into the rooms where cats were housed. Extent of resulting infections in the na?ve cats was monitored for 22 weeks by physical examination and fungal culture. RESULTS: All lufenuron-treated and control cats became infected with M canis. Cats treated with lufenuron had significantly lower infection scores, compared with control cats, during the early weeks following exposure, and there was a more prolonged initial progression phase of the infection. Once infections reached peak intensity, they resolved over similar periods in lufenuron-treated and control cats. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that oral or SC administration of lufenuron to cats, at the dosages used and under the conditions of this study, did not prevent establishment of dermatophytosis following exposure to infected cats. Infection was established more slowly among cats treated with lufenuron, but once established, infection resolved in approximately the same amount of time in lufenuron-treated as in control cats.     

Microsporum canis: Inapparent carriage by cats and the viability of arthrospores

A total of 181 dermatologically healthy pet cats from 177 different households, attending a veterinary clinic, were sampled for the presence of dermatophytes by a modified MacKenzie hair brush technique. Microsporum canis was the only dermatophyte recovered and was isolated from four cats (2.2 per cent) from four different households. In addition to clinical details, owners were questioned about the environment and management of all the cats sampled. The data regarding the cats from which M canis was recovered showed little variation from that of the culture-negative cats except that all four cats were from multi-cat (more than two cats) households, whereas only 35 per cent of the culture-negative cats were from a similar environment. The viability of M canis in infected feline hairs stored at room temperature was maintained for between 13 and 18 months.     

In vitro susceptibility to antimycotics of Microsporum canis isolates from cats.

One hundred thirty-four isolates of Microsporum canis, obtained from cats, were tested for in vitro susceptibility to various antifungal agents. The fungi were classified as susceptible, resistant, and intermediate by measuring the size of the zone of inhibited growth on yeast nitrogen base agar medium. Clotrimazole had the highest activity (99.2%), followed by tioconazole (89.6%), griseofulvin (88.8%), econazole (73.1%), ketoconazole (50.7%), miconazole (15.7%), and isoconazole (12.7%). We found 14.9% of the isolates to be susceptible to all the assayed drugs, whereas the highest resistance frequency (41.8%) was against 2 antimycotics. A simultaneous resistance to all the tested antimycotics was not found. The differences among the antifungal drugs activity were examined, and administration of drugs for which a simultaneous resistance was minimal is suggested.     

Cortisol levels in cats’ hair in presence or absence of Microsporum canis infection

The purpose of this work was to perform a preliminary screening in the domestic cat to assess the concentration of cortisol in hairs by radioimmunoassay technique (RIA) in presence or absence of Microsporum canis infections. A total of 245 cats (7 with cutaneous lesions referable to dermatophytosis and 238 apparently healthy) coming from 14 shelters were examined. M. canis was isolated in 126 (51.4%) cats. The cortisol levels were significantly higher in cats with lesions or without lesions but with a high number of colonies in the plates (⩾10 CFU) than in cats negative or with a lower number of colonies. The results obtained seem to highlight that chronic high levels of cortisol in cats could possibly promote the dermatophytes infections. Furthermore, in High-CFU asymptomatic cats, it could be present a state of infectious, and they, therefore, represents not a simple mechanical carrier.     

Environmental detection of Microsporum canis arthrospores in the households of infected cats and dogs

Microsporum canis is the dermatophyte most frequently recovered from canine and feline ringworm cases. The household environment can be contaminated both by symptomatic animals and through asymptomatic M canis carriage, resulting in a potential human health risk. The load of M canis arthrospores was determined in households harbouring infected pets, in order to evaluate the infectivity of the animals versus the environment. The environments inhabited by 30 symptomatic animals (21 cats and 9 dogs) infected by M canis were examined by sampling both surfaces and indoor air. The surfaces were examined by means of contact plates; the air sampling was performed with a Sas super-100 AIR SAMPLER (PBI, Italy). Environmental contamination was detected in all households with cats, while only four out of nine houses harbouring dogs were found positive. The frequence of isolation in each sampling, and the results in terms of colony forming units per plate in the different houses appeared to be quite homogeneous. Heavily infected environments harboured kittens only. Infected owners were observed in eight households, in all of which at least one infected cat was present. No history of human dermatophytosis in households harbouring dogs was found. On the basis of our results, infected cats appear to cause substantial environmental contamination, and provoke a substantial presence of viable airborne fungal elements. Dogs seem to be of lower importance in the spread of M CANIS: they contaminated surfaces, but they never contaminated the air. The results of this study confirm the potential leading role of the feline species in the environmental spread of M canis.     

The prevalence of immediate and delayed type hypersensitivity reactions to Microsporum canis antigens in cats

Spontaneous recovery from Microsporum canis infections in cats is thought to be dependent on the development of a competent immune response. The purpose of this study was to determine the prevalence of positive delayed type hypersensitivity reactions in cats with and without dermatophytosis. Four groups of cats were intradermally skin tested with M canis extract and test sites were evaluated both subjectively and objectively at 0, 24 and 48 h after injection. Delayed intradermal testing (IDT) reactions were absent in cats not exposed to dermatophytosis (n=20); infected-recovered cats (n=38 culture negative lesion negative and n=43 lesion negative but culture positive) had significantly larger IDT reactions than unexposed cats and cats that were still actively infected (n=18). Based on the results of this study, IDT with M canis extract can be used to assess the cellular immune response of cats with dermatophytosis.     

Microsporum gypseum isolated from ringworm lesions in a horse

Abstract

Extract

Microsporum gypseum has a world-wide distribution in soil, and it is considered to be essentially a soil inhabitant that only occasionally parasitizes animals and man (Georg, 1959 Georg, L. K. 1959. Animal Ringworm in Public Health, 3–17. U.S. Dept. of Health, Education and Welfare, Public Health Service Publ..  [Google Scholar]).     

Drug Efficacy of Terbinafine Hydrochloride (Lamisil®) During Oral Treatment of Cats,Experimentally Infected with Microsporum canis

Cats represent a primary source of Microsporum canis infections in humans. Terbinafine hydrochloride (Lamisil^®) is commonly used in the treatment of microsporosis in humans as its fungicidal action permits short periods of treatment. The aim of the present study was to estimate the efficacy of the drug in cats. Nine cats were experimentally infected with M. canis and treated with terbinafine hydrochloride at a dose of 10–20 mg/kg (once daily, SID; low‐dose group, LDG). Another nine cats were similarly infected and treated with 30–40 mg/kg SID (high‐dose group, HDG) and a further nine cats were also infected and left untreated (control group, CG). The general condition of the cats was observed daily and their clinical symptoms evaluated weekly. The cats recovery was monitored using the Wood's lamp illumination test and microscopic and fungal culture examinations. The general condition of the cats during the study was good. The cure rates of the LDG were not significantly different from the CG at any period during the treatment. However, the HDG cure rates differed significantly from the other two groups. After 109 days of treatment, when all nine cats of the HDG were healed, seven cats of the LDG and all the cats in the CG were still M. canis‐positive. This study shows that dosages of 10–20 mg/kg SID of terbinafine hydrochloride are not sufficient to terminate an experimental M. canis infection in cats within an acceptable period of time. Terbinafine hydrochloride can be used to treat dermatophytosis in cats, but a higher dosage, 30–40 mg/kg SID, should be used to achieve a cure.