Fungi in Canada: McMaster researchers survey six provinces, one territory to study trends in environmental fungi

Researchers at McMaster University have conducted a massive, Canada-wide survey of a common disease-causing fungus.

Published recently in the Canadian Journal of Microbiology, the study examined the diversity, dispersal, and evolution of Aspergillus fumigatus populations living in Canadian environments.

Led by Jianping Xu, a professor of biology at McMaster, the research team analyzed 748 A. fumigatus isolates from 21 different Canadian sites, making it the largest study of its kind.

The research showed that the vast majority of A. fumigatus populations living in Canadian environments boast a high degree of genetic diversity, which Xu says makes them extremely resilient.

“The high genetic diversity found across Canada means that the adaptive potential of our local populations of this pathogen is very high,” he says. “These fungi can mutate, recombine, and adapt quickly to overcome environmental stressors, like climate change and agricultural fungicide.”

Xu, a member of the Michael G. DeGroote Institute for Infectious Disease Research, says studies into the evolution and epidemiology of A. fumigatus are critically important, because the fungus can cause severe, opportunistic infections in humans. Most of these infections, he explains, are from environmental exposure, and the fungus itself is extremely abundant in nature.

“This particular fungal pathogen is everywhere,” he says. “We all come into contact with it every day.”

In fact, the samples under study were easily collected from mere spoonfuls of soil from urban parks, agricultural fields, and forests located in seven vastly different regions of Canada, spanning from PEI to BC and up to the Northwest Territories. In past work, Xu even collected A. fumigatus samples from the remote mountaintops of the Eastern Himalayas.

While most people can count on their immune system to eliminate A. fumigatus before it causes an infection, Xu says such extreme ubiquity and adaptability make the fungus a pathogen of serious concern — especially for immunocompromised individuals. Right now, A. fumigatus sits at the very top of the World Health Organization’s list of priority fungal pathogens.