Global warming impact on the expansion of fundamental niche of Cryptococcus gattii VGI in Europe

Abstract

In the present study, we analysed how geographical distribution of the fungal pathogen Cryptococcus gattii VGI in Europe and Mediterranean area has evolved in the last four decades based on the climatic changes, and we tried to predict the scenario for the next decade. Niche modelling by Maxent analysis showed that recent climate changes have significantly affected the distribution of the fungus revealing a gradual expansion of the fundamental niche from 1980 to 2009 followed by an impressive increase in the last decade (2010-2019) during which the environmental surface suitable for the fungal survival was more than doubled. In the next decade, our model predicted an increase in the area of distribution of C. gattii VGI from the coasts of the Mediterranean basin towards the more internal sub-continental areas. On the basis of these predictions, an increase of cases of cryptococcosis due to C. gattii VGI is expected in the next decade and a constant monitoring of the epidemiology of this fungal pathogen represents a crucial strategy to detect the onset of future outbreaks.

Fig. 1

Maps of species distribution inferred by Maxent v.3.3.3. Bioclimatic optimal conditions used to draw the distribution map of Cryptococcus gattii VGI in the 2010–2019 decade have been projected on the bioclimatic conditions existing in the past three decades to infer new distribution maps. Colour gradients represent the different probability of presence for the fungus in a specific geographical area.

Fig. 2

Maps showing the geographical areas where an increase in the probability of the presence for Cryptococcus gattii VGI has been observed. Increment values are displayed with different colours. The two pictures show the high increase in all Mediterranean area occurred in the last decade (2010–2019, right panel) compared with the low increase of the previous decade (2000–2009, left panel).

Fig. 3

Maps of species distribution predicting the expansion of fundamental niche for Cryptococcus gattii VGI in the next decade (B) compared with the present (A). The map at the lower side (C) shows the geographical areas where an increase in the probability of the presence of the fungus is expected.