Movements of male white-tailed deer (Odocoileus virginianus) are of great concern with respect to spread of chronic wasting disease (CWD) across landscapes because most yearlings males disperse and adult males have higher prevalence of CWD than do females and younger deer. We radiocollared and monitored 85 male white-tailed deer in the middle Missouri River Valley of eastern Nebraska and western Iowa, USA from 2004 to 2008. Average size ( SE) of fixed-kernel annual home ranges (95%) and core areas (50%) for resident deer were 449 ( 32) ha and 99 ( 7) ha, respectively. Resident deer exhibited a highdegree of fidelity to their home ranges. Mean overlap between consecutive annual home ranges and core areas was 81% and 74%, respectively. Average dispersal distance was 17.7 4.5 km (range 1⁄4 3–121 km) for 22 radio-marked and 6 ear-tagged yearlings. Mean spring dispersal distance (25 km) was 150% greater than fall (10 km). Dispersal direction from Desoto National Wildlife Refuge (DNWR) was bimodal on a northwest to southeast axis that followed the Missouri River corridor. Of 22 yearlings that dispersed 18 (82%) established adult home ranges within the river valley. Dispersal movements of yearling males represent the greatest risk for rapid spread of diseases from infected source populations. Disease management efforts in riparian habitats should target male fawns and yearling males for removal in areas within or immediately adjacent to river corridors. 2011 The Wildlife Society.

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Movements of White-Tailed Deer in RiparianHabitat: Implications for Infectious Diseases

The intestinal microbiota has important functions that contribute to host health. The compositional dynamics of microbial communities are affected by many factors, including diet and presence of pathogens. In contrast to humans and domestic mammals, the composition and seasonal dynamics of intestinal microbiota of wildlife species remain comparatively understudied. White-tailed deer (Odocoileus virginianus) is an ecologically and economically important wildlife species that inhabits agricultural ecosystems and is known to be a reservoir of enteric pathogens. Nevertheless, there is a lack of knowledge of white-tailed deer intestinal microbiota diversity and taxonomic composition. This study's first objective was to characterize and compare the intestinal microbiota of 66 fecal samples from white-tailed deer collected during two sampling periods (March and June) using 16S rDNA pyrosequencing. Associations between community diversity and composition and factors including season, sex, host genetic relatedness, and spatial location were quantified. Results revealed that white-tailed deer intestinal microbiota was predominantly comprised of phyla Firmicutes and Proteobacteria, whose relative frequencies varied significantly between sampling periods. The second objective was to examine the associations between the presence of Escherichia coli and Salmonella, and microbiota composition and diversity. Results indicated that relative abundance of some microbial taxa varied when a pathogen was present. This study provides insights into microbial compositional dynamics of a wildlife species inhabiting coupled natural and agricultural landscapes. Data focus attention on the high prevalence of Proteobacteria particularly during the summer and highlight the need for future research regarding the role of white-tailed deer as a natural pathogen reservoir in agroecosystems.

Intestinal Microbial Community Dynamics of White-Tailed Deer (Odocoileus virginianus) in an Agroecosystem

Disease is often expected to limit host populations, but diseases do not always dramatically reduce host numbers and often have no effect. The impact of a fungal pathogen (Entomophaga grylli pathotype 1) on grasshopper (Camnula pellucida) populations was studied in a field experiment. We tested whether the effects of disease on grasshopper survival were additive, with disease mortality summing with other mortality sources to determine the total population mortality rate; or whether they were compensatory, where disease mortality simply replaces mortality from other sources so that the total population mortality rate remains unchanged. We examined grasshopper survival in relation to differences in disease exposure, host density levels, and host developmental stage. The effects of disease varied with grasshopper developmental stage and density. Disease mortality increased by 60% at high grasshopper density compared to low-density treatments, and decreased when grasshoppers fully matured. Despite increased rates of disease mortality at high densities, the total mortality rate was not notably higher in diseased grasshoppers (87%) compared to disease-free counterparts at high densities (83%), indicating that a large percentage of disease mortality simply replaced mortality from food limitation. Additive responses were supported in early and late instars, with disease exposure resulting in decreased grasshopper survival. In contrast, the effect of disease on adults was inconclusive. Yet, the disease did not affect adult survival, suggesting that adult disease mortality is compensatory. Therefore, disease reduction of grasshopper populations (additive mortality) is more likely to occur during earlier developmental stages, when hosts are most vulnerable to disease, and at low host densities when food is abundant. Combined, our results emphasize the importance of host dynamics and food availability in how this host–pathogen system responds to disease. Accordingly, compensatory vs. additive mortality may need to be considered when examining how disease ultimately affects host population dynamics.

Host dynamics determine responses to disease: additive vs. compensatory mortality in a grasshopper–pathogen system

The Norwegian Food Safety Authority (Mattilsynet, NFSA) and the Norwegian Environment Agency (Miljødirektoratet, NEA) requested the Norwegian Scientific Committee for Food Safety (Vitenskapskomiteen for mattrygghet, VKM) for a scientific opinion on Chronic wasting disease (CWD) in cervids. The project was divided into two phases, and VKM published the scientific opinion from phase I “CWD in Norway” in June 2016. The current report is the result of phase II. 
 VKM was asked to provide updated information on food safety, aspects important for transmission of CWD within and between populations and species, and the potential origin of the disease in Norway. Moreover, VKM was asked to highlight important risk factors with regard to disease transmission, and how these risk factors might affect choice of management strategy. Finally, VKM was asked to highlight relevant management strategies from North America or elsewhere. 
 VKM appointed a working group consisting of one member of the Panel on Microbial Ecology, one member of the Panel on Biological Hazards, and five external experts, as well as VKM`s secretariat to answer the questions from NEA and NFSA. One member of the Panel on Alien Organisms and Trade in Endangered Species (CITES), one member of the Panel on Animal Health and Welfare, as well as one member of the Panel on Biological Hazards commented on the draft report. The Panel on Biological Hazards assessed and approved the final report. 
 Background: 
Chronic wasting disease (CWD) is a prion disease that affects deer, moose, reindeer, and related species (cervids). Prion diseases are chronic neurodegenerative diseases that occur naturally in humans and ruminants, and are invariably fatal. Some prion diseases, such as classical scrapie in sheep and goats and chronic wasting disease (CWD) in cervids, are contagious, spreading directly between animals or via environmental contamination. In contrast, prion diseases known to affect humans are not known to be contagious. 
 Prions are extraordinary agents consisting of misfolded protein aggregates that are remarkably stable and can remain infectious for years in the environment. Prion proteins are present in most animals, but the misfolding makes them very hard to break down. Consequently, misfolded prion proteins accumulate in the brain and eventually in other tissues, causing damage to those tissues. 
Until recently, CWD was only known from North America and South Korea. During a routine marking event in April 2016, a female reindeer (Rangifer tarandus) of the Nordfjella wild reindeer herd in Norway exhibited unusual behaviour, and died shortly afterwards. This unusual death was routinely investigated, and the animal was diagnosed with CWD. This was the first time CWD had been diagnosed outside North America and South Korea and the first case of natural CWD in reindeer. 
In addition, two moose (Alces alces) in Selbu, Norway were diagnosed with CWD in May 2016. Selbu is located approximately 300 km northeast of the Nordfjella mountain range. Currently there is considerable uncertainty regarding the nature of the CWD diagnosed in the two moose. Some of the characteristics of these cases indicate consistency with atypical prion disease, as described in domestic animals, but a final conclusion depends on the results from ongoing investigations. 
Following the diagnosis in reindeer, Norwegian authorities initiated a screening programme in which hunters were requested to collect tissue and the heads of dead cervids during the 2016 hunting season. Animals that had died from causes other than hunting were also tested for CWD. Since March 2016, 4629 samples of moose, 2550 samples of red deer, 627 samples of roe deer, 860 samples of reindeer, 2494 semi-domesticated reindeer, 163 farmed deer and 104 samples of unidentified species were tested for CWD. 
Two additional cases of CWD were diagnosed in wild reindeer in the Nordfjella population. Together with a clinical, pathological and epidemiological picture consistent with contagious CWD, as described from North America, this indicated that there is an ongoing outbreak of CWD in the wild reindeer population of the northern part of Nordfjella wild reindeer range. 
Results: 
An increase in the distribution and prevalence of CWD will increase exposure of other species, including domestic animals and humans, to this infectious agent. There is currently no evidence indicating transmission of CWD to domestic animals or humans, either by direct contact with cervids, cervid meat, or other products from cervids, or through the environment. VKM continues to support the conclusion from phase I concerning food safety of meat from cervids, that the zoonotic risk of CWD (transmission to humans) is very low. Preliminary results from characterisation of the moose cases and the agent involved indicate that important features deviate significantly from those found in the reindeer and in North American cervids, raising uncertainty with regards to the zoonotic potential. Therefore, based on the data currently available, VKM is not able to reach an evidence-based conclusion regarding the food safety of meat from moose and other cervids infected with this potentially new variant of CWD. 
Whereas direct transmission (animal-to-animal) seems most important in the early phases of a CWD epizootic, the role of indirect transmission (from the environment) increases as the prevalence increases. Once contagious CWD is established, it is very likely that the disease will increase in prevalence within the affected population and spread to contact populations. The rate of increase in prevalence, the resulting impact in a given population, and the efficacy of spread will depend on a range of environmental factors, and the characteristics of the species and population in question. For example, in affected populations of a gregarious species like reindeer, CWD is likely to lead to population decline in the long-term. 
Experiences from North America indicate that prions aggregate in the environment, making eradication of the disease extremely difficult once it has been allowed to develop and become endemic. It is therefore important that efficient measures are implemented at the VKM Report 2017:9 9 earliest opportunity in order to have a realistic chance of eradicating local occurrence of CWD and preventing further spread. 
Contagious CWD found in a confinable population, such as many wild reindeer herds, should be managed by eradication of the host population, fallowing of the area (> 5 years), and restocking from a healthy population. 
The report explains that culling of the Nordfjella reindeer herd is a necessary, immediate response to the current situation. However, as part of an adaptive management strategy, this measure should be under active review and may be revised in the event that new cases of CWD are discovered. 
In contrast, in continuous populations, such as most red deer, moose, and roe deer populations, spatially targeted culling within a defined containment zone should be used to control a CWD outbreak. Confinement of CWD-infected populations should be increased where possible and contact with other populations of cervids restricted, for example by fencing, herding, enhancing natural or man-made obstacles, or decreasing the densities of the relevant cervid populations. 
Potential “hotspots” for disease transmission (supplementary salt-licks, supplementary feeding sites etc.) should be eliminated in areas with CWD as well as the surrounding areas, and should further be considered for other parts of the country. Precautionary measures should be implemented to prevent anthropogenic spread of the disease. 
Finally, increasing the national surveillance of CWD in cervids is essential to ensure that there is a comprehensive basis for future evidence-based management. This is required to ensure that cases and spread of disease are identified as soon as possible, as late discovery will limit the chances for successful eradication of CWD in Norway.

CWD in Norway – a state of emergency for the future of cervids (Phase II). Opinion of the panel on Biological Hazards

Chronic wasting disease (CWD) is a fatal disease of North American Cervidae. New York State (NYS, USA) successfully managed an outbreak of CWD in 2005 in both captive and wild white-tailed deer (Odocoileus virginianus) with no reoccurrence of the disease as of 2015. To attain maximum compliance and efficacy of management actions for prevention of CWD entry, understanding the varied risk perceptions will allow for targeted, proactive communication efforts to address divergences between expert-derived risk assessments and stakeholder risk perceptions. We examined perceived risks associated with CWD introduction and exposure among agricultural and wildlife agency professionals within and outside of NYS, as well as stakeholder groups (e.g., hunters and captive cervid owners). We measured perceived risk using a risk assessment questionnaire online via Qualtrics survey software and evaluated similarities within, as well as differences in, perception among participant groups. New York State biologists employed by the Department of Environmental Conservation and independent non-NYS wildlife and agricultural professionals thought CWD risks associated with captive cervids were high; captive cervid owners thought risks for wild and captive cervids were low. Agriculture and wildlife professional groups agreed on general risk perceptions. We ranked 15 individual risk hazards into high and low–medium categories based on all responses. Differences between groups were most evident in hypothetical disease pathways. Any pathway involving inter-state import of live cervids received high ranking for all groups except captive cervid owners. Comparatively low-risk perceptions by captive cervid operators may stem from misinformation, lack of understanding of testing programs, and indemnity payments for animal depopulation. Communication and education directed at areas of disagreement may facilitate effective disease prevention and management. © 2016 The Wildlife Society.

Exploring perceptions about chronic wasting disease risks among wildlife and agriculture professionals and stakeholders

We studied the seasonal home range of individual white-tailed deer (Odocoileus virginianus) as it related to landscape pattern (forest-edge density; the ratio of agriculture to forest), local deer density, and harvest intensity in a population managed for control of chronic wasting disease in south central Wisconsin. The ratio of agriculture to forest showed strong positive correlation to home range size for most age and sex classes, while forest edge density was inversely related to home range size for adult females. Individual home range size proved largely independent of density and harvest intensity. It is likely that socio-spatial factors (i.e., fidelity) and the availability of food and cover influence home range size more strongly than hunting pressures or density reductions. This suggests localized reductions may create areas of low density without changing the behavior patterns of the population. Our findings suggest a more spatially-targeted effort to reduce density, by removal of socia...

https://bioone.org/journals/the-american-midland-naturalist/volume-173/issue-2/amid-173-02-267-282.1/Movements-and-Habitat-Interactions-of-White-tailed-Deer--Implications/10.1674/amid-173-02-267-282.1.pdf

Movements and Habitat Interactions of White-tailed Deer: Implications for Chronic Wasting Disease Management

We analyzed the survival rates of 160 Odocoileus virginianus (White-tailed Deer) over 6 years in the area of Wisconsin's highest prevalence of chronic wasting disease. Survival was very high for all age/sex classes and varied by season but not by year. When we omitted hunting mortality, yearlings and adults had similar annual survival, with survival of males (0.83–0.89) slightly lower than survival of females (0.91). However, including hunting mortality reduced survival of yearling and adult males to 0.72 and 0.41, and survival of yearling and adult females to 0.88 and 0.83, respectively. We also observed seasonal patterns, characterized by reduced survival across all sex and age classes during the rut season (10 October to 31 December), which includes the period of maximum hunting. Six mortalities (8.3%) were associated with chronic wasting disease, including one deer that died from the disease. We find no evidence that CWD was substantially increasing mortality rates during the duration of our ...

https://bioone.org/journals/northeastern-naturalist/volume-19/issue-1/045.019.0105/Survival-of-White-tailed-Deer-in-Wisconsins-Chronic-Wasting-Disease/10.1656/045.019.0105.pdf

Jeromy C. Chamberlin

Papers

Movements and Habitat Interactions of White-tailed Deer: Implications for Chronic Wasting Disease Management

Survival of White-tailed Deer in Wisconsin's Chronic Wasting Disease Zone