title: Bacterial Genomics Reveal the Complex Epidemiology of an Emerging Pathogen in Arctic and Boreal Ungulates.
abstract: Northern ecosystems are currently experiencing unprecedented ecological change, largely driven by a rapidly changing climate. Pathogen range expansion, and emergence and altered patterns of infectious disease, are increasingly reported in wildlife at high latitudes. Understanding the causes and consequences of shifting pathogen diversity and host-pathogen interactions in these ecosystems is important for wildlife conservation, and for indigenous populations that depend on wildlife. Among the key questions are whether disease events are associated with endemic or recently introduced pathogens, and whether emerging strains are spreading throughout the region. In this study, we used a phylogenomic approach to address these questions of pathogen endemicity and spread forErysipelothrix rhusiopathiae, an opportunistic multi-host bacterial pathogen associated with recent mortalities in arctic and boreal ungulate populations in North America. We isolatedE. rhusiopathiaefrom carcasses associated with large-scale die-offs of muskoxen in the Canadian Arctic Archipelago, and from contemporaneous mortality events and/or population declines among muskoxen in northwestern Alaska and caribou and moose in western Canada. Bacterial genomic diversity differed markedly among these locations; minimal divergence was present among isolates from muskoxen in the Canadian Arctic, while in caribou and moose populations, strains from highly divergent clades were isolated from the same location, or even from within a single carcass. These results indicate that mortalities among northern ungulates are not associated with a single emerging strain ofE. rhusiopathiae, and that alternate hypotheses need to be explored. Our study illustrates the value and limitations of bacterial genomic data for discriminating between ecological hypotheses of disease emergence, and highlights the importance of studying emerging pathogens within the broader context of environmental and host factors.
authors.affiliation: Faculty of Veterinary Medicine, University of CalgaryCalgary, AB, Canada; Institute of Biodiversity, Animal Health and Comparative Medicine, University of GlasgowGlasgow, UK.
authors.forename: Taya L
authors.initials: TL
authors.lastname: Forde
authors.affiliation: Faculty of Veterinary Medicine, University of Calgary Calgary, AB, Canada.
authors.forename: Karin
authors.initials: K
authors.lastname: Orsel
authors.affiliation: Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow Glasgow, UK.
authors.forename: Ruth N
authors.initials: RN
authors.lastname: Zadoks
authors.affiliation: Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow Glasgow, UK.
authors.forename: Roman
authors.initials: R
authors.lastname: Biek
authors.affiliation: Alaska Science Center, U.S. Geological Survey Anchorage, AK, USA.
authors.forename: Layne G
authors.initials: LG
authors.lastname: Adams
authors.affiliation: Faculty of Veterinary Medicine, University of Calgary Calgary, AB, Canada.
authors.forename: Sylvia L
authors.initials: SL
authors.lastname: Checkley
authors.affiliation: Environment and Natural Resources, Government of Northwest Territories Inuvik, NT, Canada.
authors.forename: Tracy
authors.initials: T
authors.lastname: Davison
authors.affiliation: Faculty of Veterinary Medicine, University of Calgary Calgary, AB, Canada.
authors.forename: Jeroen
authors.initials: J
authors.lastname: De Buck
authors.affiliation: Department of Environment, Government of Nunavut Kugluktuk, NU, Canada.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Dumond
authors.affiliation: Environment and Natural Resources, Government of Northwest Territories Yellowknife, NT, Canada.
authors.forename: Brett T
authors.initials: BT
authors.lastname: Elkin
authors.affiliation: fRI Research Hinton, AB, Canada.
authors.forename: Laura
authors.initials: L
authors.lastname: Finnegan
authors.affiliation: Faculty of Veterinary Medicine, University of Calgary Calgary, AB, Canada.
authors.forename: Bryan J
authors.initials: BJ
authors.lastname: Macbeth
authors.affiliation: Ministry of Forests, Lands and Natural Resource Operations, Government of British Columbia Nanaimo, BC, Canada.
authors.forename: Cait
authors.initials: C
authors.lastname: Nelson
authors.affiliation: Department of Environment, Government of Nunavut Kugluktuk, NU, Canada.
authors.forename: Amanda
authors.initials: A
authors.lastname: Niptanatiak
authors.affiliation: Department of Environment, Government of Nunavut Cambridge Bay, Nunavut, Canada.
authors.forename: Shane
authors.initials: S
authors.lastname: Sather
authors.affiliation: Ministry of Forests, Lands and Natural Resource Operations, Government of British Columbia Nanaimo, BC, Canada.
authors.forename: Helen M
authors.initials: HM
authors.lastname: Schwantje
authors.affiliation: Faculty of Veterinary Medicine, University of Calgary Calgary, AB, Canada.
authors.forename: Frank
authors.initials: F
authors.lastname: van der Meer
authors.affiliation: Faculty of Veterinary Medicine, University of CalgaryCalgary, AB, Canada; Canadian Wildlife Health CooperativeCalgary, AB, Canada.
authors.forename: Susan J
authors.initials: SJ
authors.lastname: Kutz
keywords: Erysipelothrix; bacteria; emerging disease; genomics; molecular epidemiology; ungulate; wildlife