Researchers hunt for deadly amphibian fungus in Manitoba wetlands

A graduate student is sampling frogs and salamanders across southern Manitoba to determine if a deadly fungal disease blamed for dozens of amphibian extinctions has arrived in the province.

"It is quite literally everywhere on our continent …. There's no way we don't have this pathogen here," said Jackie Tran, a master's student at Brandon University.

The disease, chytridiomycosis, causes thickening skin that falls off, breathing and eating struggles, and a shutdown of the immune system.

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It is directly responsible for the extinction of at least 90 amphibian species and has tanked numbers in more than 500 others.

Chytrid has been described as "the worst infectious disease ever recorded among vertebrates."

While not yet officially detected in Manitoba, Tran said the province's chytrid-free designation might be a mirage due to a lack of surveillance.

"There's reported presence everywhere around our province. Now, that doesn't mean we don't have the pathogens here, it just means we haven't been on top of surveillance up until now," he said.

The disease has been confirmed in frogs in Ontario, near the Manitoba border, as well as in the Northwest Territories, North Dakota, Minnesota and Saskatchewan.

Nearly half of Alberta frog populations sampled between 2006 and 2010 tested positive, and studies in British Columbia found it in one in 10 amphibians.

The northern leopard frog, a species of special concern in Manitoba, has seen population declines across Canada, and chytrid is suspected in a major die-off in the province five decades ago.

"Heaps of dead and dying frogs" up to a metre high were observed along wetland shores at the time, but no samples were taken to confirm the cause.

"That's kind of been taken as a sign to not prioritize this research," Tran said.

His work marks the start of a proactive monitoring program at Brandon University that his supervisor, Pamela Rutherford, plans to continue.

"If we can get out front of this, this can help sort of limit some of these declines," said Rutherford, an associate professor in the department of biology.

Tran's research is part of a broader pathogen monitoring program that started in the United States.

He is sampling a variety of Manitoba's 16 amphibian species, including wood frogs, tiger salamanders and northern leopard frogs.

Rutherford said pathogens spread well in wetlands degraded by human activity, so Tran's work to identify those habitats has broad value.

"The health of the wetland tells you about not just how the frogs are doing, but it tells you how the fish … how the insects are doing, how the plants are doing, and so it's all interrelated," she said.

"The health of wetlands is also directly connected with human health as well: healthy wetlands, healthy environments."

Rutherford said there is reason to believe the risk to Prairie amphibians is increasing.

"With a changing environment, a changing climate, things could get a lot worse," Tran said.

If the pathogen is confirmed in Manitoba, there may be a glimmer of hope.

Field experiments by the Wilder Institute and the Calgary Zoo suggest young leopard frogs can be inoculated against the worst effects of chytrid.

They gave young frogs from an infected B.C. population baths in a diluted itraconazole solution.

More than a quarter of treated frogs survived winter, compared with an estimated half a per cent of untreated frogs.

"We had about 60 times the overwinter survival for treated frogs, which confirms that chytrid fungus is what has hampered our reintroduction efforts until now," said Lea Randall, senior manager of conservation programs at the Wilder Institute.

With files from CBC News