Origin and distribution of Sporothrix globosa causing sapronoses in Asia

Abstract

Purpose: The aim of the study was to evaluate the main sources and epidemiological patterns and speculate on the evolutionary origin of Sporothrix globosa in Asia.

Methodology: Case and case series literature on sporotrichosis in Asia from January 2007 onwards were reviewed using meta-analysis. Phylogenetic analysis of relevant S. globosa was carried out on the basis of concatenated sequences of ITS, TEF3 and CAL. A haplotype network of CAL sequences of 281 Sporothrix isolates was analysed to determine the population structure of S. globosa.

Results: Nearly all cases of sporotrichosis caused by S. globosa in Asia were human. In contrast to the remaining pathogenic Sporothrix species, feline transmission was exceptional; nearly all regional cat-associated cases were caused by Sporothrix schenckii. While the latter species was highly variable and showed recombination, S. globosa seemed to be a clonal offshoot, as was Sporothrix brasiliensis. The origin of the segregants was located in an area of high variability in S. schenckii with a relatively high frequency of Asian strains.

Conclusion: In Asia, S. globosa was the prevalent species. The low diversity of S. globosa suggested a recent divergence with a founder effect of low variability from the variable ancestral species, S. schenckii.