Zoonotic sporotrichosis. Transmission to humans by infected domestic cat scratching: report of four cases in São Paulo, Brazil

Abstract

Background: Sporotrichosis is a chronic, granulomatous, deep mycosis caused by the dimorphic fungus Sporothrix schenckii that usually results in indolent cutaneous lesions.

Objective: To describe four cases of human sporotrichosis transmitted by domestic cats in south-eastern Brazil.

Methods: Confirmation of the diagnosis was performed by histopathology, culture, and/or inoculation of hamsters.

Results: In all cases, the clinical findings in both cat and human groups were highly distinctive of the disease. In all human cases, there was a previous history of cat scratching before the development of lymphocutaneous lesions. Histopathology of the human lesions demonstrated the classical granulomatous and exudative pattern with scarce or absent fungal elements. Conversely, in cats, the cutaneous lesions were multiple, extensive, necrotic, exudative, and ulcerated. Histopathology revealed a widespread histiocytic reaction with a large number of fungal organisms. Disseminated lymphatic and visceral mycotic infection was observed in two necropsied cats.

Conclusions: Domestic cats may be an important carrier of agents of sporotrichosis to humans.