Origin of tropical pathogen C. gattii traced to the Amazon

Researchers of Centrum Wiskunde & Informatica (CWI) took part in a large-scale research project, led by Centraalbureau voor Schimmelcultures (KNAW), that traced the journey of the tropical pathogen Cryptococcus gattii, which recently emerged in North America, Australia and the Mediterranean.

Over ten years ago, C. gatti appeared out of nowhere in the temperate climate of Vancouver Island. The yeast mainly infected humans with a strong immune system: hundreds of otherwise healthy people were infected during the Canadian outbreak. The researchers found that not the pathogen itself, but the environment has changed, causing the exotic species to thrive outside tropical South America.

Researchers from various disciplines cooperated in the project, including microbiologists, geneticists and mathematicians. They showed that the origin of the yeast can be traced to the Amazon rainforest, and that there is little difference between the yeasts that emerged in the outbreaks worldwide. The researchers proved that while the lineage that caused the Vancouver Island outbreak was genetically different from the others, they were still derived from the same species. The temperate sea climate of Vancouver Island, South-West Australia and the Mediterranean appears to have become a fertile soil for tropical yeasts.

Ferry Hagen and Teun Boekhout of the Centraalbureau voor Schimmelcultures led the research project that shed new light on the tropical yeast. There are however many more unknowns to the outbreaks. Ferry Hagen: “Our next goal is to determine by which methods C. gatti spreads. Does it travel by sea water, through the air or does it hitch a ride on human transportation? And why does it mainly affects humans with a healthy immune system?’

The research results were published in today in PLOS ONE in the article Ancient dispersal of the human fungal pathogen Cryptococcus gattii from the Amazon Rainforest. Leo van Iersel, Gunnar Klau, Steven Kelk and Leen Stougie of CWI’s Life Sciences group cooperated in the project.

More information:
KNAW press release (in Dutch)