scholarly journals Too much of a good thing: resource provisioning alters infectious disease dynamics in wildlife

2014 ◽  
Vol 10 (7) ◽  
pp. 20140309 ◽  
Author(s):  
Daniel J. Becker ◽  
Richard J. Hall

Provisioning of abundant food resources in human-altered landscapes can have profound effects on wildlife ecology, with important implications for pathogen transmission. While empirical studies have quantified the effects of provisioning on host behaviour and immunology, the net interactive effect of these components on host–pathogen dynamics is unknown. We use simple compartmental models to investigate how provisioning-induced changes to host demography, contact behaviour and immune defence influence pathogen invasion and persistence. We show that pathogen invasion success and equilibrium prevalence depend critically on how provisioning affects host immune defence and that moderate levels of provisioning can lead to drastically different outcomes of pathogen extinction or maximizing prevalence. These results highlight the need for further empirical studies to fully understand how provisioning affects pathogen transmission in urbanized environments.

Behaviour ◽  
2014 ◽  
Vol 152 (1) ◽  
pp. 83-105 ◽  
Author(s):  
Quinn M.R. Webber ◽  
Liam P. McGuire ◽  
Steven B. Smith ◽  
Craig K.R. Willis

The influence of behaviour on host-parasite dynamics has theoretical support but few empirical studies have examined this influence for wild-captured hosts, especially in colonial species, which are thought to face generally high risk of exposure. Behavioural tendencies of hosts in novel environments could mediate host exposure. We tested the hypothesis that behavioural tendencies of hosts, and host sex and age, correlate with prevalence and intensity of ectoparasites in a gregarious mammal, the little brown bat (Myotis lucifugus). We also tested whether relationships between host behaviour and parasite prevalence and intensity would vary between taxa of ectoparasites which differ in host-seeking behaviour. We predicted that individual hosts displaying active and explorative behaviours would have higher prevalence and intensity of parasites that depend on physical contact among hosts for transmission (mites) but that host behaviour would not influence prevalence and intensity of mobile ectoparasites with active host-seeking behaviour (fleas). We recorded behavioural responses of wild-captured bats in a novel-environment test and then sampled each individual for ectoparasites. After accounting for age and sex we found mixed support for our hypotheses in some but not all demographics. More active adult and young of the year (YOY) males were more likely to host mites while more active adult and YOY females were less likely to host fleas. Our results highlight possible differences in the influence of host and parasite behaviour on parasite transmission dynamics for colonial compared to non-colonial species and have conservation implications for understanding pathogen transmission in bat white-nose syndrome and other wildlife diseases.


2019 ◽  
Author(s):  
Katherine M. McClure ◽  
Amy T. Gilbert ◽  
Richard B. Chipman ◽  
Erin Rees ◽  
Kim M. Pepin

ABSTRACTAnimal movement influences the spatial spread of wildlife infectious diseases through host-host contact structure and hence pathogen transmission. Wildlife disease hosts vary in characteristics related to pathogen transmission, which can increase the spread and intensity of disease outbreaks. The consequences of home range size variation on wildlife disease dynamics are poorly understood, but could help to predict disease spread and determine more effective disease management strategies.We developed a spatially-explicit individual-based model to examine the effect of variation in host home range size on the spatial spread rate, persistence, and incidence of rabies virus (RABV) in raccoons (Procyon lotor). We tested the hypothesis that host home range area variation decreases vaccination effectiveness in wildlife host populations following pathogen invasion into a vaccination zone.We simulated raccoon demography and RABV dynamics across a range of magnitudes and variances in weekly home range radius distributions for raccoons, and compared results to conditions that assumed a fixed host home range area. We examined how variable host home range radius distributions influenced the relative effectiveness of three components of orally-baited raccoon RABV vaccination (ORV) programs—timing and frequency of bait delivery, width of the zone where ORV baits were delivered, and proportion of hosts immunized.Variability in home range radius distributions increased RABV spread rates by 1.2 - 5.2-fold compared to simulations with fixed radii. More variable host home range radius distributions decreased relative vaccination effectiveness by 71% compared to less variable host home range radius distributions under conventional vaccination conditions. We found that vaccination timing was more influential for vaccination effectiveness than vaccination frequency or vaccination zone width.Our results suggest that variation in wildlife home range exploration increases the spatial spread and incidence of wildlife disease. Our vaccination results underscore the importance of prioritizing individual-level space use data collection to understand the dynamics of wildlife diseases and plan their effective control and elimination.


2020 ◽  
Author(s):  
Bo Zhang ◽  
Yingdan Yuan ◽  
Karolina M. Pajerowska-Mukhtar ◽  
Michelle Afkhami ◽  
Alan Hastings ◽  
...  

Abstract Background Soil microbiomes play important roles in invasion biology, yet it is often treated as a ‘black box’ in modeling or large-scale field studies. Hence, investigating the change of association between invasive vegetation and soil microbes under changing environmental conditions, and exploring the genetic functions of associated microbiomes will provide a deeper understanding of invasion mechanisms. We performed a microcosm experiment with cogongrass (Imperata cylindrica (L.) P. Beauv.), which is one of the 100 worst invasive plants in the world. We combined rigorous sequencing analysis, including 16S rRNA, ITS, and shotgun metagenome sequencing, for the first time, to investigate the interactive effect of change in soil water and nutrient concentrations on microbiomes diversity, composition and genetic functions under invasion. Results We found that experimental drought has a stronger effect on the bacterial community than the fungal community. We discovered an enrichment of microbial groups, including Proteobacteria, Actinobacteria, Bacteroidetes and Chloroflexi under drought treatment, could likely contribute to invasion success. Further, we showed a striking trend of induction of cell wall, membrane and desiccation-related genes in drought treatment and a marked downregulation in regular treatment, which could create a more hydrated microenvironment, facilitating biofilm formation and better protection from desiccation.Conclusions Our work contributes to highlighting the associated microbial communities may have a potential long-term impact on increasing cogongrass drought resistance, ultimately, future invasion might be severe due to the plant-microbe interaction. These findings are important because current modeling practice, lacking comprehensive consideration of the plant-microbe interaction, could lead to a significant underestimate of predictions of future invasion patterns.


2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Gabrielle L. Davidson ◽  
Niamh Wiley ◽  
Amy C. Cooke ◽  
Crystal N. Johnson ◽  
Fiona Fouhy ◽  
...  

AbstractThe microbial community in the gut is influenced by environmental factors, especially diet, which can moderate host behaviour through the microbiome-gut-brain axis. However, the ecological relevance of microbiome-mediated behavioural plasticity in wild animals is unknown. We presented wild-caught great tits (Parus major) with a problem-solving task and showed that performance was weakly associated with variation in the gut microbiome. We then manipulated the gut microbiome by feeding birds one of two diets that differed in their relative levels of fat, protein and fibre content: an insect diet (low content), or a seed diet (high content). Microbial communities were less diverse among individuals given the insect compared to those on the seed diet. Individuals were less likely to problem-solve after being given the insect diet, and the same microbiota metrics that were altered as a consequence of diet were also those that correlated with variation in problem solving performance. Although the effect on problem-solving behaviour could have been caused by motivational or nutritional differences between our treatments, our results nevertheless raise the possibility that dietary induced changes in the gut microbiota could be an important mechanism underlying individual behavioural plasticity in wild populations.


Behaviour ◽  
2018 ◽  
Vol 155 (7-9) ◽  
pp. 759-791 ◽  
Author(s):  
Marie L.J. Gilbertson ◽  
Nicholas M. Fountain-Jones ◽  
Meggan E. Craft

Abstract Utilization of contact networks has provided opportunities for assessing the dynamic interplay between pathogen transmission and host behaviour. Genomic techniques have, in their own right, provided new insight into complex questions in disease ecology, and the increasing accessibility of genomic approaches means more researchers may seek out these tools. The integration of network and genomic approaches provides opportunities to examine the interaction between behaviour and pathogen transmission in new ways and with greater resolution. While a number of studies have begun to incorporate both contact network and genomic approaches, a great deal of work has yet to be done to better integrate these techniques. In this review, we give a broad overview of how network and genomic approaches have each been used to address questions regarding the interaction of social behaviour and infectious disease, and then discuss current work and future horizons for the merging of these techniques.


2013 ◽  
Vol 103 (10) ◽  
pp. 1012-1019 ◽  
Author(s):  
S. Poggi ◽  
F. M. Neri ◽  
V. Deytieux ◽  
A. Bates ◽  
W. Otten ◽  
...  

Propagation systems for seedling growth play a major role in agriculture, and in notable cases (such as organic systems), are under constant threat from soil and seedborne fungal plant pathogens such as Rhizoctonia solani or Pythium spp. Yet, to date little is known that links the risk of disease invasion to the host density, which is an agronomic characteristic that can be readily controlled. We introduce here, for the first time in an agronomic system, a percolation framework to analyze the link. We set up an experiment to study the spread of the ubiquitous fungus R. solani in replicated propagation systems with different planting densities, and fit a percolation-based epidemiological model to the data using Bayesian inference methods. The estimated probability of pathogen transmission between infected and susceptible plants is used to calculate the risk of invasion. By comparing the transmission probability and the risk values obtained for different planting densities, we are able to give evidence of a nonlinear relationship between disease invasion and the inter-plant spacing, hence to demonstrate the existence of a spatial threshold for epidemic invasion. The implications and potential use of our methods for the evaluation of disease control strategies are discussed.


1988 ◽  
Vol 16 (1) ◽  
pp. 101-128
Author(s):  
W. Rayack

This article uses a microunit analysis to examine cyclical changes in the distribution of earnings. The analysis departs from earlier studies in several respects. It relies on a more cautious definition of family income class, calculates recession-induced changes in the Gini coefficient by estimating losses for each household in the sample, and measures the distributional effects of cyclical changes in wage rates. The procedures guard against a bias toward findings of regressivity. Yet the results indicate a generally regressive pattern that is complicated by substantial losses among certain high-wage categories. At the same time, the approach identifies several channels through which losses are distributed. Specifically, the analysis links the pattern of losses to allocation rules based on occupation and tenure status. Moreover, the results indicate that wage-decay effects reinforce the regressive tendencies. These tenure and wage effects have not received attention in prior empirical studies of recession incidence although theory suggests that they play a major role.


2017 ◽  
Author(s):  
David P. Hoytema van Konijnenburg ◽  
Bernardo S. Reis ◽  
Virginia Pedicord ◽  
Julia Farache ◽  
Gabriel D. Victora ◽  
...  

SummaryIntestinal intraepithelial lymphocytes (IELs) are located at the critical interface between the intestinal lumen, which is chronically exposed to food and microbes, and the core of the body. Using high-resolution microscopy techniques and intersectional genetic tools, we investigated the nature of IEL responses to luminal microbes. We observed that TCRγδ IELs exhibit distinct location and movement patterns in the epithelial compartment that were microbiota-dependent and quickly altered upon enteric infections. These infection-induced changes included increased inter-epithelial cell (EC) scanning, anti-microbial gene expression and glycolysis. Direct modulation of glycolysis was sufficient to change γδ IEL behavior and susceptibility to early pathogen invasion. Both γδ IEL behavioral and metabolic changes were dependent on EC pathogen sensing. Our results uncover a coordinated EC–IEL response to enteric infections that modulates lymphocyte energy utilization and dynamics and supports maintenance of the intestinal epithelial barrier.


2019 ◽  
Author(s):  
Gabrielle L. Davidson ◽  
Niamh Wiley ◽  
Amy C. Cooke ◽  
Crystal N. Johnson ◽  
Fiona Fouhy ◽  
...  

ABSTRACTThe microbial community in the gut is influenced by environmental factors, especially diet, which can moderate host behaviour through the microbiome-gut-brain axis. However, the ecological relevance of microbiome-mediated behavioural plasticity in wild animals is unknown. We presented wild-caught great tits (Parus major) with a problem-solving task and showed that performance was weakly associated with variation in the gut microbiome. We then manipulated the gut microbiome by feeding birds one of two diets that differed in their relative levels of fat, protein and fibre content: an insect diet (low content), or a seed diet (high content). Microbial communities were less diverse among individuals given the insect compared to those on the seed diet. Individuals were less likely to problem-solve after being given the insect diet, and the same microbiota metrics that were altered as a consequence of diet were also those that correlated with variation in problem solving performance. Although the effect on problem-solving behaviour could have been caused by motivational or nutritional differences between our treatments, our results nevertheless raise the possibility that dietary induced changes in the gut microbiota could be an important mechanism underlying individual behavioural plasticity in wild populations.


2016 ◽  
Vol 13 (2) ◽  
pp. 1-14
Author(s):  
MAHNA Khan

Vector-borne diseases (VBDs) of zoonotic importance are the global threat in the human life and on animal welfare as well. Many vector-borne pathogens (VBPs) have appeared in new regions in the past two decades, while many endemic diseases have increased in incidence. Although introductions and emergence of endemic pathogens are often considered to be distinct processes, many endemic pathogens are actually spreading at a local scale coincident with habitat change. Key differences between dynamics and diseases burden result from increased pathogen transmission following habitat change, deforestation and introduction life into new regions. Local emergence of VBPs are commonly driven by changing in ecology (deforestation, massive natural calamities, civil wares etc.), altered human behavior, enhanced enzootic cycles, pathogen invasion from anthropogenic trade and travel, genomic changes of pathogens to coup up with the new hosts, vectors, and climatic conditions and adaptability in wildlife reservoirs. Once a pathogen is established, ecological factors related to vector and host characteristics can shape the evolutionary selective pressure and result in increased use of people as transmission hosts. West Nile virus (WNV), Nipah virus and Chikungunya virus (CHIKV) are among the best-understood zoonotic vector-borne pathogens (VBPs) to have emerged in the last two decades and showed just how explosive epidemics can be in new regions. Zoonotic VBPs that are likely introduced into new regions include Rift Valley Fever and Japanese Encephalitis viruses (JEV) in the Americas, Venezuelan equine encephalitis virus in Eurasia or Africa, Crimean-Congo Hemorrhagic Fever virus (CCHFV) in new parts of Eurasia. Vector-borne diseases currently impose global burden on public health and animal welfare including widespread formerly zoonotic human diseases, such as malaria, leishmania and dengue fever, as well as zoonotic diseases for which humans are dead end hosts, such as Lyme disease, WNV and CCHF. It requires highly equipped laboratory facilities and technical manpower to address emergence and re-emergence of vector-borne zoonotic diseases. Financial and technological hurdles persist in developing countries, making diagnosis and control facility difficult where these diseases are stubbornly most prevalent. Development of technological and highly knowledgeable manpower is the key to protect public health and eco-health. An awareness building about the changing risk of VBPs to prevent introduction foreign pathogens is far more difficult because this is commonly an inevitable consequence of the globalization of trade and travel and in most cases is accidental. Designing of active surveillance of the deadly infectious pathogens by combining the expertise of veterinary and human health could play pivotal roles towards reducing burden of VBPs. History suggests that successful control of VBPs requires prompt identification, swift action, mobilization of fund for developing technical expertise and occasionally by using draconian social measures.DOI: http://dx.doi.org/10.3329/bjvm.v13i2.26614Bangl. J. Vet. Med. (2015). 13 (2): 1-14


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