Autochthonous and dormant Cryptococcus gattii infections in Europe

Abstract

Until recently, Cryptococcus gattii infections occurred mainly in tropical and subtropical climate zones. However, during the past decade, C. gattii infections in humans and animals in Europe have increased. To determine whether the infections in Europe were acquired from an autochthonous source or associated with travel, we used multilocus sequence typing to compare 100 isolates from Europe (57 from 40 human patients, 22 from the environment, and 21 from animals) with 191 isolates from around the world. Of the 57 human patient isolates, 47 (83%) were obtained since 1995. Among the 40 patients, 24 (60%) probably acquired the C. gattii infection outside Europe; the remaining 16 (40%) probably acquired the infection within Europe. Human patient isolates from Mediterranean Europe clustered into a distinct genotype with animal and environmental isolates. These results indicate that reactivation of dormant C. gattii infections can occur many years after the infectious agent was acquired elsewhere.

Figure

Maximum-likelihood phylogenetic analysis based on 10-loci multilocus sequence type data of Cryptococcus gattii isolates (condensed). Phylogenetic relatedness of 150 STs representing the 291 C. gattii isolates, calculated by using the maximum-likelihood algorithm and rooted by using the 2 C. neoformans reference strains CBS8710 (genotype AFLP1/VNI) and CBS10513 (genotype AFLP2/VNIV). Closely related sequence types were collapsed into 1 branch shown by multiple sequence type numbers. Boldface indicates sequence types that are within a shaded area belong to a specified C. gattii cluster; B, M, PNW, and VIO represent clusters from Brazil; Mediterranean Europe; the US Pacific Northwest outbreak; and the Vancouver Island, British Columbia, Canada, outbreak, respectively. AFLP, amplified fragment length polymorphism; ST, sequence type. Scale bar indicates number of substitutions per site. See Technical Appendix Figure for a detailed phylogenetic analysis.