Dynamics of Prion Disease Transmission in Mule Deer

Miller, Michael W.; Hobbs, N. Thompson; Tavener, Simon

doi:10.1890/1051-0761(2006)016[2208:dopdti]2.0.co;2

Cited by 111 publications

(156 citation statements)

References 26 publications

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“…An additional experiment by Miller et al showed that CWDinfected carcasses allowed to decay naturally in confined pastures can lead to CWD infections in captive deer, demonstrating the potential for environmental contamination to spread infection [55]. Modelling studies have provided further support that environmental contamination is likely playing a significant role in transmitting CWD [53,56]. Additionally, infectious prions have been demonstrated to bind soil particles and remain infectious to animals by both intracerebral and oral exposure routes [37,38].…”

Section: Disease Control Challenges Posed By Cwdmentioning

confidence: 99%

A prion disease of cervids: Chronic wasting disease

2008

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-Chronic wasting disease (CWD) is a prion disease of deer, elk, and moose, initially recognized in Colorado mule deer. The discovery of CWD beyond the borders of Colorado and Wyoming, in Canada and as far east as New York, has led to its emergence as a prion disease of international importance. Epidemiological studies indicate that CWD is horizontally transmitted among free-ranging animals, potentially indirectly by prion-containing secreta or excreta contaminating the environment. Experimental CWD transmission attempts to other wild and domestic mammals and to transgenic mice expressing the prion protein of cattle, sheep, and humans have shed light on CWD species barriers. Transgenic mice expressing the cervid prion protein have proven useful for assessing the genetic influences of Prnp polymorphisms on CWD susceptibility. Accumulating evidence of CWD pathogenesis indicates that the misfolded prion protein or prion infectivity seems to be widely disseminated in many nonneural organs and in blood. This review highlights contemporary research findings in this prion disease of free-ranging wildlife.

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Section: Disease Control Challenges Posed By Cwdmentioning

confidence: 99%

A prion disease of cervids: Chronic wasting disease

2008

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“…The discrete-time analogs of continuous-time disease models (e.g., Miller et al 2006, Yee et al 2011) are more tractable because data taken at discrete intervals can be matched with model predictions. Parameter estimation and analysis of systems of discrete-time equations, also called matrix models, have seen broad application in population ecology (Caswell 1988).…”

Section: Data Assimilation For Models Of Infectious Diseasementioning

confidence: 99%

“…Our estimate of R 0 includes proper estimates of uncertainty, which is rare for estimates in wildlife. We know of only one other instance where this has been done (Miller et al 2006). Credible intervals for R 0 (1.47, 2.32) are not markedly different from the point estimate ;2.5 coarsely derived from assuming that 40% of the adult females are susceptible in a steady-state population (Anderson and May 1991).…”

Section: Understanding Brucellosis In the Yellowstone Bisonmentioning

confidence: 99%

State‐space modeling to support management of brucellosis in the Yellowstone bison population

Hobbs

Geremia

Treanor

et al. 2015

Ecological Monographs

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Abstract. The bison (Bison bison) of the Yellowstone ecosystem, USA, exemplify the difficulty of conserving large mammals that migrate across the boundaries of conservation areas. Bison are infected with brucellosis (Brucella abortus) and their seasonal movements can expose livestock to infection. Yellowstone National Park has embarked on a program of adaptive management of bison, which requires a model that assimilates data to support management decisions. We constructed a Bayesian state-space model to reveal the influence of brucellosis on the Yellowstone bison population. A frequency-dependent model of brucellosis transmission was superior to a density-dependent model in predicting out-of-sample observations of horizontal transmission probability. A mixture model including both transmission mechanisms converged on frequency dependence. Conditional on the frequency-dependent model, brucellosis median transmission rate was 1.87 yr À1 . The median of the posterior distribution of the basic reproductive ratio (R 0 ) was 1.75. Seroprevalence of adult females varied around 60% over two decades, but only 9.6 of 100 adult females were infectious. Brucellosis depressed recruitment; estimated population growth rate k averaged 1.07 for an infected population and 1.11 for a healthy population. We used five-year forecasting to evaluate the ability of different actions to meet management goals relative to no action. Annually removing 200 seropositive female bison increased by 30-fold the probability of reducing seroprevalence below 40% and increased by a factor of 120 the probability of achieving a 50% reduction in transmission probability relative to no action. Annually vaccinating 200 seronegative animals increased the likelihood of a 50% reduction in transmission probability by fivefold over no action. However, including uncertainty in the ability to implement management by representing stochastic variation in the number of accessible bison dramatically reduced the probability of achieving goals using interventions relative to no action. Because the width of the posterior predictive distributions of future population states expands rapidly with increases in the forecast horizon, managers must accept high levels of uncertainty. These findings emphasize the necessity of iterative, adaptive management with relatively short-term commitment to action and frequent reevaluation in response to new data and model forecasts. We believe our approach has broad applications.

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“…CWD can be passed vertically from mother to offspring and horizontally upon direct contact as well as indirectly through contamination of water and feed by saliva and/or feces [5][6][7]. CWD seems more likely to occur where elk or deer are crowded or where they congregate at human-made feed and water stations [8].…”

Section: Isrn Biomathematicsmentioning

confidence: 99%

Modeling Gender-Structured Wildlife Diseases with Harvesting: Chronic Wasting Disease as an Example

Al-arydah

Smith

Lutscher

2012

ISRN Biomathematics

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Chronic wasting disease (CWD) is a prion infectious disease that affects members of the deer family in North America. Concerns about the economic consequences of the presence of CWD have led management agencies to seek effective strategies to control CWD distribution and prevalence. Current mathematical models are either based on complex simulations or overly simplified compartmental models. We develop a mathematical model that includes gender structure to describe CWD in a logistically growing population. The model includes harvesting as a management strategy for the disease. We determine the stability conditions of the disease-free equilibrium for the model and calculate the basic reproduction number. We find an optimum interval of harvesting: with too little harvesting, the disease persists, whereas too much harvesting results in extinction of the population. A sensitivity analysis shows that the disease threshold is more sensitive to female than male harvesting and that harvesting has the greatest effect on the basic reproduction number. However, while harvesting may be a way to control CWD, the range of admissible harvesting rates may be very narrow, depending on other parameters.

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Dynamics of Prion Disease Transmission in Mule Deer

Cited by 111 publications

References 26 publications

A prion disease of cervids: Chronic wasting disease

A prion disease of cervids: Chronic wasting disease

State‐space modeling to support management of brucellosis in the Yellowstone bison population

Modeling Gender-Structured Wildlife Diseases with Harvesting: Chronic Wasting Disease as an Example

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