Estimating distemper virus dynamics among wolves and grizzly bears using serology and Bayesian state‐space models

Cross, P. C., van Manen, F. T., Viana, M. , Almberg, E. S., Bachen, D., Brandell, E. E., Haroldson, M. A., Hudson, P. J., Stahler, D. R. and Smith, D. W. (2018) Estimating distemper virus dynamics among wolves and grizzly bears using serology and Bayesian state‐space models. Ecology and Evolution, 8(17), pp. 8726-8735. (doi: 10.1002/ece3.4396) (PMID:30271540) (PMCID:PMC6157674)

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Abstract

Many parasites infect multiple hosts, but estimating the transmission across host species remains a key challenge in disease ecology. We investigated the within and across host species dynamics of canine distemper virus (CDV) in grizzly bears (Ursus arctos) and wolves (Canis lupus) of the Greater Yellowstone Ecosystem (GYE). We hypothesized that grizzly bears may be more likely to be exposed to CDV during outbreaks in the wolf population because grizzly bears often displace wolves while scavenging carcasses. We used serological data collected from 1984 to 2014 in conjunction with Bayesian state‐space models to infer the temporal dynamics of CDV. These models accounted for the unknown timing of pathogen exposure, and we assessed how different testing thresholds and the potential for testing errors affected our conclusions. We identified three main CDV outbreaks (1999, 2005, and 2008) in wolves, which were more obvious when we used higher diagnostic thresholds to qualify as seropositive. There was some evidence for increased exposure rates in grizzly bears in 2005, but the magnitude of the wolf effect on bear exposures was poorly estimated and depended upon our prior distributions. Grizzly bears were exposed to CDV prior to wolf reintroduction and during time periods outside of known wolf outbreaks, thus wolves are only one of several potential routes for grizzly bear exposures. Our modeling approach accounts for several of the shortcomings of serological data and is applicable to many wildlife disease systems, but is most informative when testing intervals are short. CDV circulates in a wide range of carnivore species, but it remains unclear whether the disease persists locally within the GYE carnivore community or is periodically reintroduced from distant regions with larger host populations.

Item Type:Articles
Additional Information:PCC, FTvM, and MAH are funded by the USGS. D.W.S. and D.R.S were funded by U. S. National Park Service, National Science Foundation (DEB‐0613730 and DEB‐1245373), and Yellowstone Forever. ESA is funded by the Montana Fish, Wildlife, and Parks.
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Viana, Dr Mafalda
Authors: Cross, P. C., van Manen, F. T., Viana, M., Almberg, E. S., Bachen, D., Brandell, E. E., Haroldson, M. A., Hudson, P. J., Stahler, D. R., and Smith, D. W.
College/School:College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine
Journal Name:Ecology and Evolution
Publisher:Wiley
ISSN:2045-7758
ISSN (Online):2045-7758
Published Online:05 August 2018
Copyright Holders:Copyright © 2018 The Authors
First Published:First published in Ecology and Evolution 8(17):8726-8735
Publisher Policy:Reproduced under a Creative Commons License

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