Zoonotic Epidemic of Sporotrichosis: Cat to Human Transmission

Abstract

Most of the 51 species embedded in the genus Sporothrix are nonpathogenic environmental fungi that are closely related to decaying wood, plants, and soil. However, members of the Sporothrix schenckii complex are highly successful mammal pathogens, including S. brasiliensis, S. schenckii sensu stricto (s. str.), S. globosa, and S. luriei, the causative agents of human and animal sporotrichosis [1]. Their key to success during mammal infection lies at least in part with their ability to change from a mycelial saprophytic lifestyle at 25°C in the environment to a parasitic yeast cell at an elevated temperature (35°C–37°C), such as those developed by warm-blooded hosts [2]. Typically, infection develops after traumatic inoculation of contaminated soil, plants, and organic matter into skin or mucosa. Alternatively, infection may occur during the animal transmission (cat–cat or cat–dog) and zoonotic transmission (cat–human), which has been mostly associated with scratches or bites from infected cats [2]. In Brazil, S. brasiliensis is repeatedly associated with feline infection and has consistently shown higher virulence during epizootics, as well as in murine models of sporotrichosis. A hallmark of S. brasiliensis infection is its tendency to escalate to outbreaks or epidemics among cats with high potential for zoonotic transmission. Sporotrichosis is an emergent disease and, over the past two decades, the incidence of zoonotic sporotrichosis has been on the rise, particularly in Brazil. Judging from the epizootic and zoonotic epidemics taking place in Rio de Janeiro, Brazil, tackling sporotrichosis requires the engagement of animal and human health policies to reduce the transmission chain of Sporothrix.