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Model Points to Feces and Alternative Hosts in Muskox Bacterial Disease

Close-up portrait of a muskox feeding on grass
Research · Disease, parasites & microbiology

A study published in Ecological Modelling on 17 April 2026 used a multi-host epidemiological model to examine how the bacterium Erysipelothrix rhusiopathiae may persist and spread in Arctic muskox (Ovibos moschatus) populations. The bacterium has been associated with acute deaths and mass mortalities of muskoxen in the Canadian Arctic, including outbreaks first documented on Banks and Victoria islands in 2012 and later on Ellesmere Island. The model addresses how the bacterium may persist and spread through the host community and environment; it does not model the clinical course of disease within an individual muskox.

The model represented muskoxen and an alternative host, parameterized using Arctic foxes, together with direct transmission and two environmental sources: feces and infected carcasses. The Arctic fox therefore served as the model’s data-based alternative-host example, not as proof that foxes drive the observed muskox outbreaks. With all modelled transmission routes included, the estimated basic reproduction number, R0, was 15.1. R0 describes how many new infections one infection is expected to generate in a susceptible system; values above 1 allow transmission to sustain itself in the model. Direct transmission alone gave an R0 of 10.0 and fecal transmission alone 5.7, while carcass-only transmission produced an R0 of 0.045 under the study’s parameter estimates.

Schematic of Erysipelothrix rhusiopathiae transmission among muskoxen, an alternative host and environmental sources in the Canadian Arctic
Figure 1 from Vargas Soto et al. (2026) shows the modelled transmission system and the Canadian Arctic context. CC BY 4.0.

Environmental persistence strongly shaped modelled transmission

Processes that controlled environmental transmission, particularly bacterial shedding and persistence outside the host, had the strongest influence on R0 in the fecal-transmission scenarios. When both hosts were included, R0 was especially sensitive to the alternative host’s density, transmission coefficients and shedding rate. The numerical model also showed that disease-induced mortality could drive strong muskox population declines, and that an alternative host could accelerate those declines by allowing transmission pressure to remain high even as muskox density fell.

The authors identified environmental reservoirs—places such as contaminated soil and ponds where bacteria may persist outside an animal—together with overlap among potential host species as important priorities for empirical work. They noted that the wider Arctic host system may include foxes, wolves, polar bears, caribou, hares, lemmings and ravens.

Sources and image credit

  1. Vargas Soto, J. S., Reyne, M., Wooten, M., Radhakrishnan, S., Mavrot, F., Kutz, S., Forde, T., & Morgan, E. R. (2026). Models reveal the importance of alternative hosts and environmental transmission for emergence of bacterial disease in muskoxen in the Arctic. Ecological Modelling, 517, 111602. https://doi.org/10.1016/j.ecolmodel.2026.111602Primary open-access research article available online 17 April 2026 under CC BY 4.0. The multi-host model examined Erysipelothrix rhusiopathiae transmission in Canadian Arctic muskoxen via direct contact, fecal environmental transmission, carcasses and an alternative host parameterized with Arctic fox data.

Image: Peter Pearsall / U.S. Fish and Wildlife Service / Wikimedia Commons — muskox (Ovibos moschatus) feeding near Nome, Alaska, USA, 12 June 2018. Illustrative photograph from an Arctic/sub-Arctic setting, not an animal from the disease model. · Public Domain — U.S. Fish and Wildlife Service · Source

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