The context dependent effects of host competence, competition, and the pathogen transmission mode on disease prevalence

2021 ◽  
Author(s):  
Michael H. Cortez ◽  
Meghan A. Duffy
Keyword(s):  
Disease Prevalence ◽  
Pathogen Transmission ◽  
Transmission Mode ◽  
Host Competence ◽  
Context Dependent

scholarly journals Null expectations for disease dynamics in shrinking habitat: dilution or amplification?

2017 ◽  
Vol 372 (1722) ◽  
pp. 20160173 ◽  
Author(s):  
Christina L. Faust ◽  
Andrew P. Dobson ◽  
Nicole Gottdenker ◽  
Laura S. P. Bloomfield ◽  
Hamish I. McCallum ◽  
...  
Keyword(s):  
Infectious Disease ◽  
Habitat Loss ◽  
Disease Risk ◽  
Dilution Effect ◽  
Well Being ◽  
Pathogen Transmission ◽  
Policy Implications ◽  
Infection Prevalence ◽  
Density Dependent ◽  
Host Competence

As biodiversity declines with anthropogenic land-use change, it is increasingly important to understand how changing biodiversity affects infectious disease risk. The dilution effect hypothesis, which points to decreases in biodiversity as critical to an increase in infection risk, has received considerable attention due to the allure of a win–win scenario for conservation and human well-being. Yet some empirical data suggest that the dilution effect is not a generalizable phenomenon. We explore the response of pathogen transmission dynamics to changes in biodiversity that are driven by habitat loss using an allometrically scaled multi-host model. With this model, we show that declining habitat, and thus declining biodiversity, can lead to either increasing or decreasing infectious-disease risk, measured as endemic prevalence. Whether larger habitats, and thus greater biodiversity, lead to a decrease (dilution effect) or increase (amplification effect) in infection prevalence depends upon the pathogen transmission mode and how host competence scales with body size. Dilution effects were detected for most frequency-transmitted pathogens and amplification effects were detected for density-dependent pathogens. Amplification effects were also observed over a particular range of habitat loss in frequency-dependent pathogens when we assumed that host competence was greatest in large-bodied species. By contrast, only amplification effects were observed for density-dependent pathogens; host competency only affected the magnitude of the effect. These models can be used to guide future empirical studies of biodiversity–disease relationships across gradients of habitat loss. The type of transmission, the relationship between host competence and community assembly, the identity of hosts contributing to transmission, and how transmission scales with area are essential factors to consider when elucidating the mechanisms driving disease risk in shrinking habitat. This article is part of the themed issue ‘Conservation, biodiversity and infectious disease: scientific evidence and policy implications'.

scholarly journals Evolutionary bi-stability in pathogen transmission mode

2010 ◽  
Vol 277 (1688) ◽  
pp. 1735-1742 ◽  
Author(s):  
F. van den Bosch ◽  
B. A. Fraaije ◽  
F. van den Berg ◽  
M. W. Shaw
Keyword(s):  
Pathogen Transmission ◽  
Transmission Mode

scholarly journals What Does Tolerance Mean for Animal Disease Dynamics When Pathology Enhances Transmission?

2019 ◽  
Vol 59 (5) ◽  
pp. 1220-1230 ◽  
Author(s):  
Amberleigh E Henschen ◽  
James S Adelman
Keyword(s):  
Graphical Models ◽  
Tissue Level ◽  
Pathogen Transmission ◽  
Infectious Period ◽  
Disease Dynamics ◽  
Animal Populations ◽  
Damage Repair ◽  
Host Competence ◽  
And Control ◽  
Damage Avoidance

Abstract Host competence, or how well an individual transmits pathogens, varies substantially within and among animal populations. As this variation can alter the course of epidemics and epizootics, revealing its underlying causes will help predict and control the spread of disease. One host trait that could drive heterogeneity in competence is host tolerance, which minimizes fitness losses during infection without decreasing pathogen load. In many cases, tolerance should increase competence by extending infectious periods and enabling behaviors that facilitate contact among hosts. However, we argue that the links between tolerance and competence are more varied. Specifically, the different physiological and behavioral mechanisms by which hosts achieve tolerance should have a range of effects on competence, enhancing the ability to transmit pathogens in some circumstances and impeding it in others. Because tissue-based pathology (damage) that reduces host fitness is often critical for pathogen transmission, we focus on two mechanisms that can underlie tolerance at the tissue level: damage-avoidance and damage-repair. As damage-avoidance reduces transmission-enhancing pathology, this mechanism is likely to decrease host competence and pathogen transmission. In contrast, damage-repair does not prevent transmission-relevant pathology from occurring. Rather, damage-repair provides new, healthy tissues that pathogens can exploit, likely extending the infectious period and increasing host competence. We explore these concepts through graphical models and present three disease systems in which damage-avoidance and damage-repair alter host competence in the predicted directions. Finally, we suggest that by incorporating these links, future theoretical studies could provide new insights into infectious disease dynamics and host–pathogen coevolution.

Genetic diversity of Phytophthora nicotianae reveals pathogen transmission mode in Japan

2019 ◽  
Vol 85 (3) ◽  
pp. 189-200 ◽  
Author(s):  
Auliana Afandi ◽  
Ayaka Hieno ◽  
Arif Wibowo ◽  
Siti Subandiyah ◽  
Afandi ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Pathogen Transmission ◽  
Phytophthora Nicotianae ◽  
Transmission Mode

scholarly journals Toward a unified dilution effect theory: How competence, competition, and the transmission mechanism influence disease prevalence

2020 ◽  
Author(s):  
Michael H. Cortez ◽  
Meghan A. Duffy
Keyword(s):  
Host Species ◽  
Dilution Effect ◽  
Disease Prevalence ◽  
Pathogen Transmission ◽  
Transmission Mechanism ◽  
Infection Prevalence ◽  
Host Interactions ◽  
Host Diversity ◽  
Disease Patterns ◽  
Effect Theory

ABSTRACTBiodiversity in communities is changing globally, including the gain and loss of host species in host-pathogen communities. The dilution effect argues for a mechanistic link between increased host diversity and decreased disease in a focal host. However, we currently have a limited understanding of how the pathogen transmission mechanism and between-host interactions influence whether increased host diversity leads to increased (amplification) or decreased (dilution) infection prevalence. We use a two-host-one-pathogen model to unify theory for pathogens with environmental transmission and density-dependent and frequency-dependent direct transmission. We then identify general rules governing how the pathogen transmission mechanism and characteristics of the introduced host (disease competence and competitive ability) influence whether the introduction of a second host species increases or decreases disease prevalence in a focal host. We discuss how our results yield insight into how specific biological mechanisms shape host biodiversity-disease patterns.

Observation of surface morphology by reflection electron holography

1989 ◽  
Vol 47 ◽  
pp. 536-537
Author(s):  
N. Osakabe ◽  
J. Endo ◽  
T. Matsuda ◽  
A. Tonomura
Keyword(s):  
Phase Shift ◽  
Surface Morphology ◽  
High Sensitivity ◽  
High Energy ◽  
Path Difference ◽  
Transmission Mode ◽  
Electron Holography ◽  
Dynamical Process ◽  
High Vertical Resolution ◽  
Amplification Technique

Progress in microscopy such as STM and TEM-TED has revealed surface structures in atomic dimension. REM has been used for the observation of surface dynamical process and surface morphology. Recently developed reflection electron holography, which employes REM optics to measure the phase shift of reflected electron, has been proved to be effective for the observation of surface morphology in high vertical resolution ≃ 0.01 Å.The key to the high sensitivity of the method is best shown by comparing the phase shift generation by surface topography with that in transmission mode. Difference in refractive index between vacuum and material Vo/2E≃10-4 owes the phase shift in transmission mode as shownn Fig. 1( a). While geometrical path difference is created in reflection mode( Fig. 1(b) ), which is measured interferometrically using high energy electron beam of wavelength ≃0.01 Å. Together with the phase amplification technique , the vertivcal resolution is expected to be ≤0.01 Å in an ideal case.

Forming Impressions of Personality

2014 ◽  
Vol 45 (3) ◽  
pp. 153-163 ◽  
Author(s):  
Sanne Nauts ◽  
Oliver Langner ◽  
Inge Huijsmans ◽  
Roos Vonk ◽  
Daniël H. J. Wigboldus
Keyword(s):  
Impression Formation ◽  
Context Dependent

Asch’s seminal research on “Forming Impressions of Personality” (1946) has widely been cited as providing evidence for a primacy-of-warmth effect, suggesting that warmth-related judgments have a stronger influence on impressions of personality than competence-related judgments (e.g., Fiske, Cuddy, & Glick, 2007 ; Wojciszke, 2005 ). Because this effect does not fit with Asch’s Gestalt-view on impression formation and does not readily follow from the data presented in his original paper, the goal of the present study was to critically examine and replicate the studies of Asch’s paper that are most relevant to the primacy-of-warmth effect. We found no evidence for a primacy-of-warmth effect. Instead, the role of warmth was highly context-dependent, and competence was at least as important in shaping impressions as warmth.

Memorial Consequences of Environmental Context Change in Children and Adults

2010 ◽  
Vol 57 (6) ◽  
pp. 455-461 ◽  
Author(s):  
Alp Aslan ◽  
Anuscheh Samenieh ◽  
Tobias Staudigl ◽  
Karl-Heinz T. Bäuml
Keyword(s):  
Elementary School ◽  
Young Adults ◽  
Episodic Memory ◽  
Middle Childhood ◽  
First Graders ◽  
Fourth Graders ◽  
Environmental Context ◽  
Context Change ◽  
Context Dependent

Changing environmental context during encoding can influence episodic memory. This study examined the memorial consequences of environmental context change in children. Kindergartners, first and fourth graders, and young adults studied two lists of items, either in the same room (no context change) or in two different rooms (context change), and subsequently were tested on the two lists in the room in which the second list was encoded. As expected, in adults, the context change impaired recall of the first list and improved recall of the second. Whereas fourth graders showed the same pattern of results as adults, in both kindergartners and first graders no memorial effects of the context change arose. The results indicate that the two effects of environmental context change develop contemporaneously over middle childhood and reach maturity at the end of the elementary school days. The findings are discussed in light of both retrieval-based and encoding-based accounts of context-dependent memory.

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