© Wild Wonders of Europe / Munier / WWF

Ice-age relics

13 March 2019

This article originally appeared in The Circle: What happens after 1.5°C?. The Circle shares perspectives from across the Arctic, and the views expressed here are not necessarily those of WWF. See all Circle issues here.

From the massive decline of sea ice to changes in the smallest microbes, climate change is dramatically altering the Arctic ecosystem. Increasingly, new diseases, or “new to science” diseases, are being found in Arctic wildlife. But are diseases really on the increase? And if so, what are the consequences and what should we be doing about it? SUSAN KUTZ and PRATAP KAFLE have found that ice-age relics—the muskox and its parasites—can teach us a lot about how climate change is affecting wildlife diseases and people in the Arctic.

FOR GENERATIONS, northern Indigenous Peoples have cohabited with and depended on wildlife—and healthy wildlife remain key to maintaining the physical, spiritual and economic health of northern communities.

Yet increasingly, alarmist reports of “killer cat parasites” or “zombie bacteria” in Arctic wildlife are causing concern for northern people who have depended on wildlife as a source of food for generations. Our collective task now is to better understand the impact of climate change on the health of Arctic wildlife so we can predict and detect changes, manage for healthy populations, and ensure that these animals continue to exist for generations to come.

The muskox and its lungworm, Umingmakstrongylus pallikuukensis, offer a chance to understand the relationship between climate change and emerging diseases in the Arctic. Known as “Up” for short, the muskox lungworm was first discovered in 1988. Its name is derived from the Inuinnaqtun word “Umingmak” (meaning muskox) and “pallik kuuk,” the local place name where the parasite was first discovered.

This impressive roundworm reaches up to 65 cm in length and lives coiled in nodules in the lungs of muskoxen. Adult worms can produce millions of eggs every day. They hatch into larvae that journey up the animal’s respiratory tract and are later swallowed and passed in the feces. The larvae then penetrate the foot of a slug or snail, where they develop until they reach the infective stage. Muskoxen are infected by accidentally eating these infected slugs, or infective larvae which leave the slugs and remain in the water or vegetation.

Until the 1990s, these roundworms were restricted to the western mainland of the Canadian Arctic. This was presumably due to climate, since the parasite’s ability to develop in slugs and snails depends on temperature. In fact, prior to 1990, larvae generally required two full summers to reach the infective stage. But warmer temperatures have accelerated this development. In 2008, Up was found on southern Victoria Island, Nunavut for the first time.

Since then, community members and scientists have watched the lungworm expand its range rapidly north and east on the island. This fieldwork, together with lab-based ecological studies and habitat modelling, links the lungworm’s expanded range to ongoing Arctic warming.
Lungworms do not directly kill muskoxen, nor can they infect people. But their climate-driven range expansion alerted scientists to the fact that other, less well-known diseases may also be changing. For example, in 2010, unusually high numbers of dead muskoxen were reported on Victoria Island.

Veterinarians determined that the cause of death was a bacterium called Erysipelothrix rhusiopathiae. Since this bacterium had not previously been reported in the Arctic — nor in muskoxen — scientists and local hunters and trappers have been working together to determine if it is in fact new or was just previously undetected, and whether there are other health concerns for muskoxen. They also wonder if the sudden appearance of E. rhusiopathiae and its widespread impact—it is associated with a high mortality rate and population declines—are linked to climate change.

What they know for sure is that this bacteria can also infect people, so ongoing partnership and communication with hunters has been essential to provide a message that balances the need for hunters to protect themselves while acknowledging the importance of muskoxen for food security.

Up, the muskox lungworm, may be the poster child for how climate change can affect parasites in the Arctic. But the emergence of E. rhusiopathiae as an important cause of death in muskoxen— as well as hunters’ observations of other “new” diseases—remind us that there are likely many pathogens in the Arctic whose existence we don’t even know about yet. Nor do we yet understand how climate change may be influencing their impacts on wildlife and people.

What is clear is that, in this vast landscape, science alone will not be able to offer all the answers. We need to draw on multiple bodies of knowledge— including western science and local and Indigenous knowledge—to understand what diseases are present, what new diseases are emerging, and how climate change is altering their dynamics in Arctic wildlife. Such information will be critical for us to anticipate emerging disease threats and implement measures to conserve and protect unique species and the northern people who depend on them.

SUSAN KUTZ is a professor at the University of Calgary, Canada. Her work focuses on muskox health in the changing Arctic.

PRATAP KAFLE is a researcher at Dr. Kutz’s lab, investigating the impacts of climate change on lungworm distribution.