| Summary: | Sporotrichosis, caused by agents of the fungal genus Sporothrix, occurs
worldwide, but the infectious species are not evenly distributed. Sporothrix
propagules usually gain entry into the warm-blooded host through minor trauma to the skin
from contaminated plant debris or through scratches or bites from felines carrying the
disease, generally in the form of outbreaks. Over the last decade, sporotrichosis has
changed from a relatively obscure endemic infection to an epidemic zoonotic health
problem. We evaluated the impact of the feline host on the epidemiology, spatial
distribution, prevalence and genetic diversity of human sporotrichosis. Nuclear and
mitochondrial markers revealed large structural genetic differences between S.
brasiliensis and S. schenckii populations, suggesting that the interplay
of host, pathogen and environment has a structuring effect on the diversity, frequency and
distribution of Sporothrix species. Phylogenetic data support a recent habitat
shift within S. brasiliensis from plant to cat that seems to have occurred in
southeastern Brazil and is responsible for its emergence. A clonal structure was found in
the early expansionary phase of the cat–human epidemic. However, the prevalent
recombination structure in the plant-associated pathogen S. schenckii generates a
diversity of genotypes that did not show any significant increase in frequency as
etiological agents of human infection over time. These results suggest that closely
related pathogens can follow different strategies in epidemics. Thus, species-specific
types of transmission may require distinct public health strategies for disease
control.
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