Volume 18, Number 1—January 2012
Temperate Climate Niche for Cryptococcus gattii in Northern Europe
To the Editor: Cryptococcus gattii was considered to be geographically restricted to countries with tropical and subtropical climates until 1999, when an outbreak of cryptococcosis in humans and animals occurred in the temperate climate of Vancouver Island, British Columbia, Canada (1). Montagna et al. reported the first environmental C. gattii in Europe from the Mediterranean region of Italy; these authors isolated it from 11 (4.3%) of 255 samples of plant detritus of Eucalyptus camaldulensis trees collected from the residential locality of an autochthonous case of cryptococcal meningitis caused by C. gattii in Apulia (2). These observations were recently substantiated by the isolation of C. gattii from plant debris of trees belonging to Ceratonia siliqua (carob), Pinus halepensis (stone pine), and E. camaldulensis in Spain (3). We report environmental isolation of the primary pathogenic fungus C. gattii from a forest in Berg en Dal, the Netherlands, which extends its geographic distribution to the temperate climate of northern Europe.
We investigated 112 decayed wood samples collected from inside trunk hollows of 52 living trees belonging to 5 families during April–May 2011 in Nijmegen, the Netherlands. The trees sampled were chestnut (Castanea sativa, n = 24), Douglas fir (Pseudotsuga menziesii, n = 17), oak (Quercus macranthera, n = 6), walnut (Juglans regia, n = 3), and mulberry (Morus alba, n = 2). The main criterion in selecting a tree for sampling was advanced age and presence of large trunk hollows variably sheltered from sunlight. The sampled sites had no bird nests and were apparently free from avian excreta. The decayed wood samples were collected with an in-house swabbing technique by using simplified Staib niger seed agar as described (4). The plates were incubated at 30°C and periodically observed up to 7 days for isolation of C. gattii and C. neoformans. Suspected colonies of Cryptococcus spp. were purified by dilution plating and identified by their morphologic and biochemical profiles, including development of blue color on
Identity of the isolates was confirmed by sequencing the internal transcriped spacer and D1/D2 regions, and they were genotyped by using amplified fragment-length polymorphism (AFLP) fingerprinting and multilocus sequence typing (MLST). The MLST loci CAP10, CAP59, GPD1, IGS, LAC1, MPD1, PLB1, SOD1, TEF1α, and URA5 of the environmental C. gattii isolates were amplified and sequenced, and data were compared with MLST data from a large C. gattii population study (5) and with a recently published set of clinical, animal, and environmental C. gattii isolates from Mediterranean Europe and the Netherlands (Figure) (3,6,7). In addition, the mating type was determined with PCR by using mating type–specific primers for the STE12a and α alleles (8).
Four strains of C. neoformans species complex were isolated from the 112 decayed wood samples examined from 52 trees. One strain that originated from an oak tree (Q. macranthera), was identified as C. neoformans var. grubii. The remaining 3 strains, all originating from different hollows in a Douglas fir tree, were identified as C. gattii genotype AFLP4/VGI and mating type α. The strains were deposited at the CBS-KNAW (Centraalbureau voor Schimmelcultures/Royal Netherlands Academy of Arts and Sciences) Fungal Biodiversity Centre (accession nos. CBS12349, CBS12355, and 12356), and the sequences were deposited in GenBank (accession nos. JN982044–JN982073).
MLST analysis showed that the C. gattii isolates in our study are more closely related to the clinical isolate from the Netherlands (6) and to the clinical and environmental C. gattii isolates (AFLP4/VGI) reported from the Netherlands and other countries in Europe than to isolates from outside Europe (3,7,8). The autochthonous C. gattii AFLP4/VGI isolate, CBS2502 (earlier identified as C. neoformans) isolate from the Netherlands was recovered postmortem in 1957 from the lungs of a pregnant woman with cryptococcosis (6). This patient came from a low socioeconomic strata, was unlikely to have traveled outside the Netherlands, and probably acquired the infection indigenously from an environmental source (6).
Furthermore, genotype AFLP4/VGI appears to be the genotype of C. gattii prevalent in Europe (3,7,8). Outside Europe, C. gattii has been reported from Douglas fir trees in Vancouver Island, British Columbia, Canada; however, those isolates represented another molecular type, i.e., AFLP6/VGII (9). Genotype AFLP 4/VGI C. gattii isolates have been implicated in human infections in that region, but to our knowledge, no environmental isolates have been found until now.
Our detection of C. gattii in the environment and its previous isolation from a clinical case in the Netherlands suggests that this pathogen is endemic to the temperate climate of northern Europe. This suggestion agrees with the concept emerging from a decade of investigations in Canada and the Pacific Northwest that the geographic distribution of C. gattii extends to the temperate region, albeit with another AFLP genotype (1,9,10). Further environmental studies are likely to show a wider spectrum of host trees and higher environmental prevalence of C. gattii in this continent than what appears in the literature.
This work was supported partly by Department of Science and Technology, Government of India (F. no. SR/SO/HS-62/2008) and by Labland BV, Wijchen, the Netherlands, with a research fellowship for A.C.
- Kidd SE, Hagen F, Tscharke RL, Bartlett KH, Fyfe M, MacDougall L, A rare genotype of Cryptococcus gattii caused the cryptococcosis outbreak on Vancouver Island (British Columbia, Canada). Proc Natl Acad Sci U S A. 2004;101:17258–63.
- Montagna MT, Viviani MA, Pulito A, Aralla C, Tortorano AM, Fiore L, Cryptococcus neoformans var. gattii in Italy. Note II. Environmental investigation related to an autochthonous clinical case in Apulia. J Mycol Med. 1997;7:93–6.
- Colom MF, Hagen F, Gonzalez A, Mellado A, Morera N, Linares C, Ceratonia siliqua (carob) trees as natural habitat and source of infection by Cryptococcus gattii in the Mediterranean environment. Med Mycol. 2011; Epub ahead of print.
- Randhawa HS, Kowshik T, Khan ZU. Efficacy of swabbing versus a conventional technique for isolation of Cryptococcus neoformans from decayed wood in tree trunk hollows. Med Mycol. 2005;43:67–71.
- Fraser JA, Giles SS, Wenink EC, Geunes-Boyer SG, Wright JR, Diezmann S, Same-sex mating and the origin of the Vancouver Island Cryptococcus gattii outbreak. Nature. 2005;437:1360–4.
- Janssens J, Beetstra A. Torulosis in a pregnant female, with localization in the lungs [in Dutch]. Ned Tijdschr Geneeskd. 1957;101:824–6.
- Hagen F, Burggraaf AG, Kamermans A, Sweere J, Tintelnot K, Swinne D, The occurrence of the primary pathogenic yeast Cryptococcus gattii in Europe. Mycoses. 2009;52(Supp1):57.
- Hagen F, Illnait-Zaragozi MT, Bartlett KH, Swinne D, Geertsen E, Klaassen CH, In vitro antifungal susceptibilities and amplified fragment length polymorphism genotyping of a worldwide collection of 350 clinical, veterinary, and environmental Cryptococcus gattii isolates. Antimicrob Agents Chemother. 2010;54:5139–45.
- Kidd SE, Chow Y, Mak S, Bach PJ, Chen H, Hingston AO, Characterization of environmental sources of the human and animal pathogen Cryptococcus gattii in British Columbia, Canada, and the Pacific Northwest of the United States. Appl Environ Microbiol. 2007;73:1433–43.
- Springer DJ, Chaturvedi V. Projecting global occurrence of Cryptococcus gattii. Emerg Infect Dis. 2010;16:14–20.
Suggested citation for this article: Chowdhary A, Randhawa HS, Boekhout T, Hagen F, Klaassen CH, Meis JF. Temperate climate niche for Cryptococcus gattii in northern Europe [letter]. Emerg Infect Dis [serial on the Internet] 2012 Jan [date cited]. http://dx.doi.org/10.3201/eid1801.111190
Comments to the Authors
West Nile Virus RNA
in Tissues from Donor
Transmission to Organ