Hunting strategies to increase detection of chronic wasting disease in cervids

Mysterud, Atle; Hopp, Petter; Alvseike, Kristin Ruud; Benestad, Sylvie L.; Nilsen, Erlend B.; Rolandsen, Christer Moe; Strand, Olav; Våge, Jørn; Viljugrein, Hildegunn

doi:10.1038/s41467-020-18229-7

Cited by 23 publications

(38 citation statements)

References 61 publications

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“…Moreover, surveillance without cases does not mean that the territory is CWD-free, but depends on how much effort is put into the process, and what parts of the populations are tested (slaughtered, road kills, dead found, young/old, etc.). There is now a program for establishing freedom of CWD in Norway [ 46 ].…”

Section: Resultsmentioning

confidence: 99%

Chronic Wasting Disease (CWD) in Sami Reindeer Herding: The Socio-Political Dimension of an Epizootic in an Indigenous Context

Maraud

Roturier

2021

Animals

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Chronic wasting disease (CWD) is the most transmissible of the prion diseases. In 2016, an unexpected case was found in Norway, the first in Europe. Since then, there have been 32 confirmed cases in Norway, Sweden, and Finland. This paper aims to examine the situation from a social and political perspective: considering the management of CWD in the Swedish part of Sápmi—the Sami ancestral land; identifying the place of the Sami people in the risk management–because of the threats to Sami reindeer herding that CWD presents; and understanding how the disease can modify the modalities of Indigenous reindeer husbandry, whether or not CWD is epizootic. Based on interviews with various stakeholders and by examining the social sciences literature, this paper shows that the health risk management is structured by a politico-scientific controversy about the recognition, or not, of atypical and classical CWD. The Sami herders are currently cooperating with the state authorities in the surveillance program to sample their herds. This involvement takes place in a situation where the balance of power between the Sami people and the state, or the European Union, is framed by its colonial context. This has consequences with respect to the definition of a common interest and to implementing sanitary measures. The particular features of reindeer herding are seen as a challenge to managing CWD risk, compared with European health standards. We argue that CWD will greatly modify the modalities of Indigenous reindeer herding, whether there are positive cases or not in the Sami reindeer. By implementing new health guidelines, the authorities will create a cascading effect in Sami land and its use. The CWD situation in Fennoscandia is full of uncertainty but may cause a major shift in the organization and the governance of Sápmi. In September 2020, the identification of a new CWD case in a wild reindeer in Norway started a new episode in the disease management in Fennoscandia. Our paper raises various questions linked to understanding this new step in this crisis which is not only epidemiological, but also socio-cultural and political.

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Section: Resultsmentioning

confidence: 99%

Chronic Wasting Disease (CWD) in Sami Reindeer Herding: The Socio-Political Dimension of an Epizootic in an Indigenous Context

Maraud

Roturier

2021

Animals

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“…An established population estimation model integrates four annual censuses [ 32 ]. We used previously published data on the estimated mean population sizes of Hardangervidda reindeer for 2019 [ 33 ], which are available on GitHub [ 34 ]. The population in Nordfjella Zone 1 counted 2024 individuals at the time of eradication [ 28 ].…”

Section: Methodsmentioning

confidence: 99%

“…By chance, 183 reindeer remained at the time when the last CWD-infected reindeer was removed (figure 3). The first detection of CWD in an adult male in the Hardangervidda population was partly due to the extreme male-biased harvest implemented for early disease detection [33]. These heavy harvesting rates enable a precise estimation of CWD prevalence in adult males.…”

Section: Iterative Adaptive Management Facing Uncertain Prevalencementioning

confidence: 99%

Harvest strategies for the elimination of low prevalence wildlife diseases

et al. 2021

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The intensive harvesting of hosts is often the only practicable strategy for controlling emerging wildlife diseases. Several harvesting approaches have been explored theoretically with the objective of lowering transmission rates, decreasing the transmission period or specifically targeting spatial disease clusters or high-risk demographic groups. Here, we present a novel model-based approach to evaluate alternative harvest regimes, in terms of demographic composition and rates, intended to increase the probability to remove all infected individuals in the population during the early phase of an outbreak. We tested the utility of the method for the elimination of chronic wasting disease based on empirical data for reindeer ( Rangifer tarandus ) in Norway, in populations with (Nordfjella) and without (Hardangervidda) knowledge about exact disease prevalence and population abundance. Low and medium harvest intensities were unsuccessful in eliminating the disease, even at low prevalence. High-intensity harvesting had a high likelihood of eliminating the disease, but probability was strongly influenced by the disease prevalence. We suggest that the uncertainty about disease prevalence can be mitigated by using an adaptive management approach: forecast from models after each harvest season with updated data, derive prevalence estimates and forecast further harvesting. We identified the problems arising from disease surveillance with large fluctuations in harvesting pressure and hence sample sizes. The elimination method may be suitable for pathogens that cause long-lasting infections and with slow epidemic growth, but the method should only be attempted if there is a low risk of reinfection, either by a new disease introduction event (e.g. dispersing hosts) or due to environmental reservoirs. Our simulations highlighted the short time window when such a strategy is likely to be successful before approaching near complete eradication of the population.

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“…Other model approaches, such as Bayesian weighted surveillance ( 26 ) and risk-based scenario tree modeling ( 27 , 28 ) have been proposed for the early detection of CWD and other emerging diseases. Utilizing targeted sampling of high–risk individuals may be more cost-effective and reduce the sample size needed to detect disease when compared to random or convenience sampling.…”

Section: Understanding Cwd Dynamicsmentioning

confidence: 99%

Getting in Front of Chronic Wasting Disease: Model-Informed Proactive Approach for Managing an Emerging Wildlife Disease

et al. 2021

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Continuing geographic spread of chronic wasting disease (CWD) poses a serious threat to the sustainable future of cervids and hunting in North America. Moreover, CWD has been detected in captive cervids in South Korea and, in recent years, in free-ranging reindeer in Europe (Norway). Management of this disease is limited by logistical, financial, and sociopolitical considerations, and current strategies primarily focus on reducing host densities through hunter harvest and targeted culling. The success of such strategies in mitigating the spread and prevalence of CWD only upon detection is questionable. Here, we propose a proactive approach that emphasizes pre-emptive management through purposeful integration of virtual experiments (simulating alternate interventions as model scenarios) with the aim of evaluating their effectiveness. Here, we have used a published agent-based model that links white-tailed deer demography and behavior with CWD transmission dynamics to first derive a CWD outbreak trajectory and then use the trajectory to highlight issues associated with different phases of the CWD outbreak (pre-establishment/transition/endemic). Specifically, we highlight the practical constraints on surveillance in the pre-establishment phase and recommend that agencies use a realistic detection threshold for their CWD surveillance programs. We further demonstrate that many disease introductions are “dead ends” not leading to a full epidemic due to high stochasticity and harvesting in the pre-establishment phase of CWD. Model evaluated pre-emptive (pre-detection) harvest strategies could increase the resilience of the deer population to CWD spread and establishment. We conclude it is important to adaptively position CWD management ahead of, rather than behind, the CWD front.

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Hunting strategies to increase detection of chronic wasting disease in cervids

Cited by 23 publications

References 61 publications

Chronic Wasting Disease (CWD) in Sami Reindeer Herding: The Socio-Political Dimension of an Epizootic in an Indigenous Context

Chronic Wasting Disease (CWD) in Sami Reindeer Herding: The Socio-Political Dimension of an Epizootic in an Indigenous Context

Harvest strategies for the elimination of low prevalence wildlife diseases

Getting in Front of Chronic Wasting Disease: Model-Informed Proactive Approach for Managing an Emerging Wildlife Disease

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