McMaster scientists have uncovered new evidence that the fungus causing white-nose syndrome, a deadly disease affecting bats, may be more widespread in Western Canada than existing testing methods reveal.
In a paper published in the Journal of Fungi, the researchers call for improved ways to detect the fungus, known as Pseudogymnoascus destructans (Pd), earlier and more accurately.
The fuzzy white fungus grows on the skin of infected bats during hibernation, resulting in dehydration, starvation and death. It has killed millions of bats across North America since it was first detected in New York in 2006, with some regional populations declining by more than 90 per cent.
For the study, researchers used metagenomic sequencing, a sophisticated method that analyzes all DNA in a sample rather than searching only for specific genetic markers, to analyze bat droppings (guano), wing swabs and fungal cultures collected in Alberta, British Columbia and Saskatchewan.
The analysis found clear evidence of the fungus in all nine samples examined, including several that previous laboratory tests had reported as inconclusive or negative. In comparison, standard laboratory testing (qPCR) identified the fungus in only four of those samples.
“Our findings suggest the pathogen is likely more widespread than current monitoring indicates,” says Jianping Xu, a professor in the Department of Biology at McMaster University and the study’s lead researcher.
“The testing methods widely used across North America may be missing cases, meaning the spread of the disease could be underestimated.”
The genomic data also revealed significant genetic variation among the fungal strains found in Western Canada. The results suggest the pathogen may have arrived earlier than official reports indicate and may have entered the region through multiple pathways.
Genetic analyses indicate Pd likely arrived in Alberta as early as 2015, several years before it was first officially detected in 2022 and publicly reported in 2023.
“This suggests the fungus may have been spreading quietly before we detected it,” says Xu. “That highlights the importance of strengthening surveillance in regions where the disease has not yet been formally reported.”
The study confirms earlier research showing that North American strains of Pd likely originated in Europe and spread after introduction. However, the team also found accumulating genetic mutations and visible differences in fungal growth characteristics among Alberta strains, suggesting the pathogen has evolved rapidly.
The advanced sequencing also allowed researchers to identify which bat species were present in each sample, including little brown bats and other common western Canadian species.
Western Canada is home to the country’s highest bat diversity. Bats play a critical ecological and economic role by controlling insect populations and supporting agriculture.
While traditional qPCR testing remains the standard method for routine surveillance, researchers say metagenomic sequencing offers powerful complementary advantages, particularly for early detection and deeper genetic analysis.
The team has been working with government agencies and conservation organizations to test a probiotic treatment designed to help bats resist infection.
Field trials using probiotic bacteria are already underway in parts of western North America, where the treatment is applied to bat boxes. Bats pick up the beneficial microbes and can spread them through grooming and contact with other bats.
Researchers say the approach shows promise, though the effectiveness can vary depending on the genetic variation of the fungal strains present.
This study involved collaboration with partners including the Wildlife Conservation Society Canada and was supported by Environment and Climate Change Canada. Researchers also worked with the British Columbia Ministry of the Environment, as well as provincial agencies in Alberta and Saskatchewan which provided samples for analysis.