Cat favus caused by Microsporum incurvatum comb. nov.: the clinical and histopathological features and molecular phylogeny.

Favus is a distinctive form of infection that is caused by exclusively dermatophytes. Its clinical presentation is characterized by scutula, which are concave, thick fungal crusts. The best-known examples of human scalp favus are caused by Trichophyton schoenleinii and those of mouse favus are caused by T. quinckeanum. However, other dermatophytes, such as T. violaceum, T. verrucosum, Microsporum audouinii, M. gallinae, M. gypseum, and M. canis, have been reported sporadically to cause favic lesions. Favus on cats has rarely been mentioned in the literature, and the pathogens with which it has been associated are, for the most part, unknown. Here, we examine four cat favus cases, focusing on clinical presentations and histopathological features. In all cases the etiologic agent was identified as M. incurvatum based on its morphological characteristics and sequences of internal transcribed spacers (ITS) of nuclear ribosomal DNA. Phylogenetic analysis using the neighbor-joining method, which is based on ITS, showed that these four isolates belonged to two strains of M. incurvatum; one strain was a new combination from the basionym Nannizzia incurvata.

Efficacy of miconazole nitrate against favus in oriental breed chickens.

Miconazole nitrate 2% was tested for its efficacy against Microsporum gallinae (the causative agent in favus) in a flock of various Oriental breed (Shamo and Aseel) and crossbreed chickens. Six adult males showing clinical signs of favus were randomized into control and experimental groups. The males were maintained on individual tiecords on the range, with no physical contact between birds. The experimental birds had the affected areas washed with soap and water and dried, and an ointment of miconazole nitrate 2% was applied. The experimental birds received the treatment twice a day for 34 days. Scrapings from the affected areas of all birds were cultured at the beginning and end of the test. At the end of the treatment period, the control birds were still positive for M. gallinae, but the organism could not be cultured from the treated birds.

Favus in a fighting cock caused by Microsporum gallinae.

The first diagnosis of favus in chickens in Costa Rica was made in a 1-year-old fighting cock that had lesions surrounding the comb. The etiologic agent was isolated and identified as Microsporum gallinae. The rooster recovered during topical treatment with tolnaftate and oral treatment with griseofulvin.