Fig 1.
Phylogenetic analyses correlate with ecological behavior of Sporothrix species.
Comparing the clades over the entire tree reveals a consistent decrease of bark beetle and soil association outside Ophiostoma, with a concomitant increase of vertebrate infectivity in S. brasiliensis, S. schenckii, and S. globosa. Phylogenetic tree generated by neighbor-joining analysis using partial nucleotide sequences of the rDNA operon (ITS1+5.8s+ITS2). Bootstrap value (1,000 replicates) was added to respective branches. Each species is indicated at its respective position in the phylogenetic tree. Bar = total nucleotide differences between taxa.
Fig 2.
Transmission routes in human and animal sporotrichosis.
The transmissibility between different species of clinical interest is explored based on epidemiological data. (A) Sporothrix brasiliensis is associated with large epizooties during animal horizontal transmission (purple route). This is not an exclusive host association, since S. schenckii may also infect cats but with lower frequency. Cat-borne sporotrichosis can be transmitted to humans (zoonoses) via deep scratching and biting, through which high loads of yeast cells are inoculated into to host tissue (red route). The threat of cross-species pathogen transmission (purple and red routes) poses the risk of a massive epidemic for humans in highly endemic areas. Note that Sporothrix schenckii and Sporothrix globosa cause large sapronoses (green route), while S. brasiliensis is less frequent during sapronoses. The size of the species’ circumference is proportional to the likelihood of involvement (high, medium, or low) in each transmission route. (B) In the sapronotic route (classical pathway), the presence of the etiologic agents of sporotrichosis in nature can lead to an endemic profile, with fluctuation in the number of transmissions. However, the infections remain close to the baseline over time. (C) Highly specific conditions must be met to promote pathogen expansion in plant debris (see [4]). (D) In the alternative route, feline-borne transmission via deep scratching is highly effective during animal horizontal transmission and during zoonotic transmission, placing a larger number of individuals at risk of acquiring sporotrichosis.