Deer density and disease prevalence influence transmission of chronic wasting disease in white‐tailed deer

Storm, Daniel J.; Samuel, Michael D.; Rolley, Robert E.; Shelton, Paul; Keuler, Nicholas S.; Richards, Bryan J.; Deelen, Timothy R. Van

doi:10.1890/es12-00141.1

Cited by 70 publications

(83 citation statements)

References 76 publications

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“…Our projections of CWD dynamics are limited because we cannot account for these unknown, but potentially important, effects on transmission due to accumulation of infectious prions in the environment over time. Two recent evaluations of the potential effects of soil characteristics (specifically clay content) on CWD transmission to yearling deer and on spatial patterns of CWD prevalence in Wisconsin [44], [46] failed to show an association between soil characteristics and CWD, unlike a similar study from Colorado [68]. While there is no current evidence supporting a significant role for environmental CWD transmission in Wisconsin, we cannot discount the possible influence this may have on future CWD dynamics in our study system.…”

Section: Discussioncontrasting

confidence: 65%

“…It has been suspected that FD was a dominant transmission mechanism in mule deer [5], [17]; [ but see 6], and more recently in white-tailed deer [28], [46]. Furthermore, our modeling results suggest a more recent and biologically plausible time since CWD introduction in south-central Wisconsin compared with earlier analysis [18].…”

Section: Discussionsupporting

confidence: 49%

“…However, as disease prevalence continues to increase, the rate of infection in yearling bucks will also increase [46]. Because dispersing bucks may be an important source of disease spread, these patterns suggest that CWD prevalence outside the core area will continue to grow and the disease may spread at an increasing rate.…”

Section: Discussionmentioning

confidence: 99%

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Transmission of Chronic Wasting Disease in Wisconsin White-Tailed Deer: Implications for Disease Spread and Management

et al. 2014

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Few studies have evaluated the rate of infection or mode of transmission for wildlife diseases, and the implications of alternative management strategies. We used hunter harvest data from 2002 to 2013 to investigate chronic wasting disease (CWD) infection rate and transmission modes, and address how alternative management approaches affect disease dynamics in a Wisconsin white-tailed deer population. Uncertainty regarding demographic impacts of CWD on cervid populations, human and domestic animal health concerns, and potential economic consequences underscore the need for strategies to control CWD distribution and prevalence. Using maximum-likelihood methods to evaluate alternative multi-state deterministic models of CWD transmission, harvest data strongly supports a frequency-dependent transmission structure with sex-specific infection rates that are two times higher in males than females. As transmissible spongiform encephalopathies are an important and difficult-to-study class of diseases with major economic and ecological implications, our work supports the hypothesis of frequency-dependent transmission in wild deer at a broad spatial scale and indicates that effective harvest management can be implemented to control CWD prevalence. Specifically, we show that harvest focused on the greater-affected sex (males) can result in stable population dynamics and control of CWD within the next 50 years, given the constraints of the model. We also provide a quantitative estimate of geographic disease spread in southern Wisconsin, validating qualitative assessments that CWD spreads relatively slowly. Given increased discovery and distribution of CWD throughout North America, insights from our study are valuable to management agencies and to the general public concerned about the impacts of CWD on white-tailed deer populations.

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Section: Discussioncontrasting

confidence: 65%

Section: Discussionsupporting

confidence: 49%

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Transmission of Chronic Wasting Disease in Wisconsin White-Tailed Deer: Implications for Disease Spread and Management

et al. 2014

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“…The proportion of hemoplasma-infected raccoons was greater on the undisturbed than on the urbanized island, and the proportion of hemoplasma-infected raccoons in both locations was higher than in urban cats. If hemoplasma transmission is population density dependent, an increase in hemoplasma infection in urbanized habitats is expected (55,56). We did not see evidence of this, because trapping success on the urban island (0.41 animals/trap night) was higher than on the protected island (0.24 animals/trap night).…”

Section: Resultsmentioning

confidence: 82%

Prevalence, Genotype Richness, and Coinfection Patterns of Hemotropic Mycoplasmas in Raccoons (Procyon lotor) on Environmentally Protected and Urbanized Barrier Islands

Volokhov

Hwang

Chizhikov

et al. 2017

Appl Environ Microbiol

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Raccoons (Procyon lotor) are successful urban adapters and hosts to a number of zoonotic and nonzoonotic pathogens, yet little is known about their hemoplasma infections and how prevalence varies across habitat types. This study identifies hemotropic Mycoplasma species infection in raccoons from urban and undisturbed habitats and compares hemoplasma infection in sympatric urban cats (Felis catus) from the same geographic region. We collected blood from raccoons (n ϭ 95) on an urban coastal island (n ϭ 37) and an undisturbed coastal island (n ϭ 58) and from sympatric urban cats (n ϭ 39) in Georgia, USA. Based on 16S rRNA gene amplification, 62.1% (59/95) of raccoons and 17.9% (7/39) of feral cats were positive for hemoplasma. There was a greater percentage of hemoplasma-infected raccoons on the undisturbed island (79.3% [46/58]) than on the urban island (35.1% [13/37]; 2 ϭ 16.9, df ϭ 1, P ϭ 0.00004). Sequencing of the full-length 16S rRNA gene amplicons revealed six hemoplasma genotypes in raccoons, including five novel genotypes that were distinct from three known hemoplasma species identified in the sympatric cats. In addition, the hemoplasma genotypes detected in raccoons were not identified in sympatric cats or vice versa. Although all six hemoplasma genotypes were found in raccoons from urban and undisturbed islands, coinfection patterns differed between sites and among individuals, with the proportion of coinfected raccoons being greater in the undisturbed site. This study shows that raccoons are hosts for several novel hemoplasmas and that habitat type influences infection patterns.IMPORTANCE This study provides information about novel hemoplasmas identified in raccoons (Procyon lotor), which can be used for assessments of the prevalence of these hemoplasmas in raccoon populations and for future studies on the potential pathogenic impacts of these hemoplasmas on raccoon health. Raccoons from the undisturbed habitat had a higher prevalence of hemoplasma infection than urban raccoons. There does not appear to be cross-species transmission of hemotropic mycoplasmas between urban raccoons and feral cats. Raccoons appear to be hosts for several novel hemoplasmas, and habitat type influences infection patterns.KEYWORDS raccoons, Procyon lotor, feral cats, Felis catus, hemoplasmas, wildlife, 16S rRNA gene, phylogenetic analysis, hemoplasma U rbanization is a strong ecological driver that causes significant changes in the composition of wildlife communities and in various intra-and interspecies interactions (1). Ecological responses to urbanization can lead to changes in the dynamics

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“…These results suggest that patterns of aggregation related to both within-and between-group transmission may be increasing the spread of B. abortus among elk. Such complex transmission mechanisms may occur, for example, in animals with distinct social groups that are highly connected due to group-group contact and between-group movement of certain individuals (e.g., Craft et al 2011), and may explain wildlife systems where the prevalence of disease is not described well by a linear relationship with host density (e.g., Smith et al 2009, Storm et al 2013. However, few studies have evaluated and compared the effects of density and group size measured at multiple scales or examined the relationship between density of a large mammal and rate of increase in pathogen seroprevalence.…”

Section: Discussionmentioning

confidence: 99%

A multi‐scale assessment of animal aggregation patterns to understand increasing pathogen seroprevalence

Brennan¹,

Cross²,

Higgs³

et al. 2014

Ecosphere

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Abstract. Understanding how animal density is related to pathogen transmission is important to develop effective disease control strategies, but requires measuring density at a scale relevant to transmission. However, this is not straightforward or well-studied among large mammals with group sizes that range several orders of magnitude or aggregation patterns that vary across space and time. To address this issue, we examined spatial variation in elk (Cervus canadensis) aggregation patterns and brucellosis across 10 regions in the Greater Yellowstone Area where previous studies suggest the disease may be increasing. We hypothesized that rates of increasing brucellosis would be better related to the frequency of large groups than mean group size or population density, but we examined whether other measures of density would also explain rising seroprevalence. To do this, we measured wintering elk density and group size across multiple spatial and temporal scales from monthly aerial surveys. We used Bayesian hierarchical models and 20 years of serologic data to estimate rates of increase in brucellosis within the 10 regions, and to examine the linear relationships between these estimated rates of increase and multiple measures of aggregation. Brucellosis seroprevalence increased over time in eight regions (one region showed an estimated increase from 0.015 in 1991 to 0.26 in 2011), and these rates of increase were positively related to all measures of aggregation. The relationships were weaker when the analysis was restricted to areas where brucellosis was present for at least two years, potentially because aggregation was related to disease-establishment within a population. Our findings suggest that (1) group size did not explain brucellosis increases any better than population density and (2) some elk populations may have high densities with small groups or lower densities with large groups, but brucellosis is likely to increase in either scenario. In this case, any one control method such as reducing population density or group size may not be sufficient to reduce transmission. This study highlights the importance of examining the density-transmission relationship at multiple scales and across populations before broadly applying disease control strategies.

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Deer density and disease prevalence influence transmission of chronic wasting disease in white‐tailed deer

Cited by 70 publications

References 76 publications

Transmission of Chronic Wasting Disease in Wisconsin White-Tailed Deer: Implications for Disease Spread and Management

Transmission of Chronic Wasting Disease in Wisconsin White-Tailed Deer: Implications for Disease Spread and Management

Prevalence, Genotype Richness, and Coinfection Patterns of Hemotropic Mycoplasmas in Raccoons (Procyon lotor) on Environmentally Protected and Urbanized Barrier Islands

A multi‐scale assessment of animal aggregation patterns to understand increasing pathogen seroprevalence

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