Dormant infections can become reactivated years after having been acquired on another continent.

Cryptococcosis is a major fungal disease caused by members of the Cryptococcus gattii and Cryptococcus neoformans species complexes. After more than 15 years of molecular genetic and phenotypic studies and much debate, a proposal for a taxonomic revision was made.

Recent Cryptococcus gattii infections in humans and animals, including several outbreaks in goats, were the basis of this environmental survey in six provinces of Spain. A total of 479 samples from 20 tree species were studied. Cryptococcus gattii was found for the first time in autochthonous Mediterranean trees in Spain. Fourteen isolates of this pathogen were obtained from seven trees of three different species: 12 from carob (Ceratonia siliqua), one from Mediterranean stone pine (Pinus halepensis) and another from eucalyptus (Eucalyptus camaldulensis). All C. gattii isolates were genotype AFLP4/VGI and mating type alpha, and were found to be genetically identical with C. gattii strains isolated from humans and animals in Spain. This supports the hypothesis that these trees may be a natural source for infection of humans and mammals in the Mediterranean area.

This paper has been updated to correct a spelling error concerning an author name. It previously showed as Giuseppe Griseo, however the correct spelling is Giuseppe Criseo.

In order to elucidate the distribution of Cryptococcus neoformans and C. gattii in the Mediterranean basin, an extensive environmental survey was carried out during 2012-2015. A total of 302 sites located in 12 countries were sampled, 6436 samples from 3765 trees were collected and 5% of trees were found to be colonized by cryptococcal yeasts. Cryptococcus neoformans was isolated from 177 trees and C. gattii from 13. Cryptococcus neoformans colonized 27% of Ceratonia, 10% of Olea, Platanus and Prunus trees and a lower percentage of other tree genera. The 13 C. gattii isolates were collected from five Eucalyptus, four Ceratonia, two Pinus and two Olea trees. Cryptococcus neoformans was distributed all around the Mediterranean basin, whereas C. gattii was isolated in Greece, Southern Italy and Spain, in agreement with previous findings from both clinical and environmental sources. Among C. neoformans isolates, VNI was the prevalent molecular type but VNII, VNIV and VNIII hybrid strains were also isolated. With the exception of a single VGIV isolate, all C. gattii isolates were VGI. The results confirmed the presence of both Cryptococcus species in the Mediterranean environment, and showed that both carob and olive trees represent an important niche for these yeasts.