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Inuit harvesters help detect an emerging parasitic disease in Arctic caribou

Barren-ground caribou in Nunavut landscape
Research: Disease, parasites & microbiology · Conservation: Threats

Inuit harvesters near Kugluktuk, Nunavut, helped identify an emerging disease affecting barren-ground caribou (Rangifer tarandus). In late summer 2023, harvesters described two kinds of abnormal tissue: fluid and yellow-white deposits inside the chest and abdomen, and bruised or discoloured muscle in the legs and back. They submitted samples from caribou harvested for food through a community-based wildlife-health programme.

Parasite DNA found in abnormal tissue

Researchers examined the submitted samples and tested the lesions for parasite DNA. Under the microscope, they found inflammation involving eosinophils, a type of white blood cell, and occasionally saw nematode parasites. DNA from two filarioid nematodes—parasitic roundworms—was identified: Setaria yehi and Onchocerca sp. lineage 2. These worms are transmitted by blood-feeding insects, including biting flies and mosquitoes.

The two kinds of tissue damage are biologically interesting because filarioid roundworms can inhabit different parts of the body, including body cavities and tissues around muscles. An earlier field update associated the cavity changes with Setaria and the muscle changes with Onchocerca. The later genetic study identified an Onchocerca lineage without confirming the earlier species-level name. Nor do the samples establish how widespread the condition is, because the harvesters submitted tissues that already looked abnormal.

A possible climate connection

The parasites had been circulating in caribou before 2015, while the disease syndromes associated with them have emerged more recently. The researchers suggest that climate change could be involved by altering the ecology of Arctic vectors—organisms that transmit parasites between hosts—or the animals’ susceptibility to infection. They present this as a possible explanation, not proof that climate change caused the disease.

The changes matter for caribou health and for communities that depend on the animals as food. Discoloured meat and unusual fluid can make harvested animals appear unsuitable to eat, even though the study does not demonstrate a new human infection risk. Continued surveillance led by Indigenous communities may help detect wildlife disease and support food-security decisions.

Sources and image credit

  1. Indigenous harvesters detect climate-sensitive emerging disease in barren-ground caribou (Rangifer tarandus) threatening food securityPrimærartikkel. Beskriver sykdomsutbruddet, vevsfunnene, påvisningen av parasitt-DNA, forfatternes tolkning og publiseringsdato.
  2. Outbreak of parasitic worms in Bluenose-East caribouOffisiell prosjektoppdatering om fangstfolks meldinger nær Kugluktuk sensommeren 2023 og de to undersøkte mønstrene av vevsforandringer og parasittene.

Image: Barren-ground caribou, Ennadai Lake, Nunavut. Photo: Alan D. Wilson / Wikimedia Commons, CC BY-SA 3.0. · CC BY-SA 3.0 · Source

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Disease, parasites & microbiology

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