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  • 1
    In: Ecological Solutions and Evidence, Wiley, Vol. 4, No. 1 ( 2023-01)
    Abstract: Surveillance of wildlife diseases poses considerable logistical challenges compared to that of humans or livestock. Citizen science can enable broader coverage, but building an efficient disease monitoring system that relies on hunters is challenging. Chronic wasting disease (CWD) is a lethal and infectious prion disease of cervids. Improving surveillance is important with the detection of CWD in wild reindeer ( Rangifer tarandus ) in Norway. This study describes the components of an efficient CWD monitoring system utilizing recreational hunters. We report the success of data capture after 6 years of surveillance. We provide an overview of CWD occurrence among the 24 wild reindeer areas and quantify the likelihood of disease absence in areas without detection. Surveillance aimed to test hunted reindeer aged ≥1 year. With higher quotas and extended hunting seasons, proactive surveillance was implemented in at‐risk areas. There were several challenges of population demarcation and the lack of surveys required for risk‐based sampling. Several specific tools for hunters have been developed, including digital apps for rapid reporting and feedback. Laboratory capacity was expanded, and novel statistical tools were developed for the specifics of the sampled tissues. The surveillance (2016–2021) achieved a sample return rate of 61.5% from a maximum of 22,123 harvested reindeer aged ≥1 year. Among these, 64.1% included both relevant tissues (retropharyngeal lymph nodes and brain), yielding 9412 (42.5%) complete samples of harvested reindeer. Samples originating from harvest constituted ~84% of total wild reindeer samples. CWD was detected in 2 of the 24 wild reindeer management areas. The remaining populations had a probability of CWD‐freedom from 60% to 99% (mean = 77%) at a design prevalence of 0.5%. Utilizing hunters to monitor wildlife disease appears to be the most realistic option for cervid species. However, the logistical and economic constraints are substantial and pose long‐term challenges. Considerable uncertainty about disease occurrence remains even after massive surveillance, and whether management should take preventive actions remains a challenge.
    Type of Medium: Online Resource
    ISSN: 2688-8319 , 2688-8319
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2023
    detail.hit.zdb_id: 3021448-8
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  • 2
    In: EFSA Journal, Wiley, Vol. 17, No. 11 ( 2019-11)
    Type of Medium: Online Resource
    ISSN: 1831-4732 , 1831-4732
    Language: English
    Publisher: Wiley
    Publication Date: 2019
    detail.hit.zdb_id: 2540248-1
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  • 3
    Online Resource
    Online Resource
    Wiley ; 2021
    In:  Journal of Applied Ecology Vol. 58, No. 2 ( 2021-02), p. 281-285
    In: Journal of Applied Ecology, Wiley, Vol. 58, No. 2 ( 2021-02), p. 281-285
    Abstract: International policy for the management of wildlife disease(s) plays an important role for concerted action, and changes to policy should be evidence‐based and updated as new evidence accumulates. Management of chronic wasting disease (CWD), the prion disease affecting cervids, is based on its highly contagious nature relative to most other prion diseases. These management actions are particularly invasive, with considerable biological and economic consequences. A novel type of CWD has been discovered in moose Alces alces and red deer Cervus elaphus , with prions restricted to the central nervous system (CNS). Prions in tissue outside the CNS are an indication of the contagiousness of a prion disease. As such, for this novel type of CWD, there is a lower likelihood of horizontal transmission under natural conditions. Furthermore, infected individuals were older (mean 15 years), and cases appeared with limited clustering in space and time; hence, with no indication of an epidemic outbreak. Policy implications . The annual harvest of approximately 4 million cervids in Europe each year generates considerable cultural and economic value. ‘Stamping out’ policies would be inefficient and inappropriate to control diseases with no horizontal transmission among live animals, and banning the export of meat from a region after detection of a positively tested animal would make little sense in the case of sporadic disease. The novel type of chronic wasting disease (CWD) with epidemiological characteristics clearly different from ‘classical’ and contagious CWD calls for differentiated management strategies to avoid unnecessarily invasive actions.
    Type of Medium: Online Resource
    ISSN: 0021-8901 , 1365-2664
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2021
    detail.hit.zdb_id: 2020408-5
    detail.hit.zdb_id: 410405-5
    SSG: 12
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  • 4
    In: Methods in Ecology and Evolution, Wiley, Vol. 10, No. 1 ( 2019-01), p. 134-145
    Abstract: Surveillance of wildlife diseases is logistically difficult, and imperfect detection is a recurrent challenge for disease estimation. Using citizen science can increase sample sizes, but it is associated with a cost in terms of the anatomical type and quality of the sample. Additionally, biological tissue samples from remote areas lose quality due to autolysis. These challenges are faced in the case of emerging chronic wasting disease ( CWD ) in cervids. Here, we develop a stochastic scenario tree model of diagnostic sensitivity, allowing for a mixture of tissue sample types (lymph nodes and brain) and qualities while accounting for different detection probabilities during the CWD infection, lasting 2–3 years. We apply the diagnostic sensitivity in a Bayesian framework, enabling estimation of age‐class‐specific true prevalence, including the prevalence in latent, recently infected stages. We provide a simulation framework to estimate the sensitivity of the surveillance system (i.e., the probability of detecting the infection in a given population), when detectability varies among individuals due to different disease progression. We demonstrate the utility of our framework by applying it to the recent emergence of CWD in a European population of reindeer. We estimated apparent CWD prevalence at 1.2% of adults in the infected population of wild reindeer, while the true prevalence was 1.6%. The sensitivity estimation of the CWD surveillance was performed in an adjacent small ( c . 500) and a large ( c . 10,000) reindeer population, demonstrating low certainty of CWD absence. Our method has immediate application to the mandatory testing for CWD in EU countries commencing in 2018. Similar approaches that account for latent stages and a serial disease progression in various tissues with a temporal pattern of diagnostic sensitivity may enhance the estimation of the prevalence of wildlife diseases more generally.
    Type of Medium: Online Resource
    ISSN: 2041-210X , 2041-210X
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2019
    detail.hit.zdb_id: 2528492-7
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  • 5
    In: Ecosphere, Wiley, Vol. 10, No. 11 ( 2019-11)
    Abstract: Infection patterns linked to age and sex are crucial to predict the population dynamic effects of diseases in long‐lived species. How such demographic patterns of infection arise is often multifactorial, although the cause is commonly seen as a combination of immune status as well as variation in pathogen exposure. Prion diseases are particularly interesting, as they do not trigger an adaptive immune response; hence, differences in pathogen exposure linked to behavior could be the prime determinant of the pattern of infection. In cervids, the fatal prion disease, chronic wasting disease ( CWD ), is spreading geographically, with economic and cultural consequences in affected areas in North America, and all infected individuals eventually die from disease‐associated sequelae if they live long enough. Understanding the causes of the demographic pattern of infection with CWD is therefore urgent but is limited by the fact that reported data primarily come from related deer species in North America. The recent (detected 2016) emergence of CWD among wild alpine reindeer ( Rangifer tarandus ) in Norway with a different social organization, that is, no home range behavior and no matrilineal female groups, offers an opportunity to advance our understanding of how behavior influences the infection patterns. Testing of 1081 males and 1278 females detected 19 animals positive for abnormal prion protein in brain and/or lymphatic tissues. No calves and only one male yearling were infected, with the remaining positives being adults (representing 1.5% of adult males and 0.5% of adult females). We found a strong sex‐biased infection pattern in reindeer (with infection 2.7 times more likely in adult males), which is similar to the results reported in mule deer and white‐tailed deer. The hazard of being detected as positive increased with age in males. There was no close genetic relatedness among positive animals. The results were consistent with the within‐group contact of males being a possible major route of transmission. We discuss the demographic pattern of infection with CWD in view of the lack of stable home range behavior and other key behavioral traits of reindeer relevant to understanding pathogen exposure in general.
    Type of Medium: Online Resource
    ISSN: 2150-8925 , 2150-8925
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2019
    detail.hit.zdb_id: 2572257-8
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