scholarly journals Multivariate Abundance Analysis of Multi-Host/Multi-Parasite Lungworms in a Sympatric Wild Ruminant Population

Diversity ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 227
Author(s):  
Tessa Carrau ◽  
Carlos Martínez-Carrasco ◽  
María Magdalena Garijo ◽  
Francisco Alonso ◽  
Rocío Ruiz de Ybáñez ◽  
...  
Keyword(s):  
Population Level ◽  
Parasite Load ◽  
Fallow Deer ◽  
Host Population ◽  
Marginal Effect ◽  
Wild Ruminant ◽  
Additional Species ◽  
Parasite Abundance ◽  
Associated Risk Factors ◽  
Natural Dynamics

In the analysis of a multi-host/multi-parasite system and its associated risk factors, it is particularly interesting to understand the natural dynamics among pathogens, their hosts, and the environment in wildlife populations. This analysis is particularly feasible in a scenario where multiple overlapping host populations are present in high densities, along with a complex community of parasites. We aimed to describe and analyze the naturally occurring lungworm polyparasitism in a wild ruminant community in Southeast Spain. The respiratory tracts of 250 specimens belonging to four different species (red deer, mouflon, Iberian ibex, and fallow deer) were studied. Almost half (48.0%) of the animals were infected with bronchopulmonary nematodes. Seven different nematodes were identified of which two genera (Protostrongylus spp. and Dictyocaulus spp.) and three additional species (Cystocaulus ocreatus, Muellerius capillaris, and Neostrongylus linearis) were recorded in at least two ruminants, with the mouflon as the commonest host. Our study shows a significant effect of host species and sampling area, plus a marginal effect of age, on parasite multivariate abundance at the host population level. Mouflon and adults of all hosts appear to carry the highest parasite load on average. From a spatial perspective, the highest parasite abundance was detected at the central part of the park.

scholarly journals Sarcoptic mange in wild ruminants in Spain: solving the epidemiological enigma using microsatellite markers

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Barbara Moroni ◽  
Samer Angelone ◽  
Jesús M. Pérez ◽  
Anna Rita Molinar Min ◽  
Mario Pasquetti ◽  
...  
Keyword(s):  
Microsatellite Markers ◽  
Sarcoptes Scabiei ◽  
Host Population ◽  
Sarcoptic Mange ◽  
Wild Ruminant ◽  
Capra Pyrenaica ◽  
Wild Ruminants ◽  
In The Wild ◽  
Genetic Clusters ◽  
Genetic Strains

Abstract Background In Spain, sarcoptic mange was first described in native wildlife in 1987 in Cazorla Natural Park, causing the death of nearly 95% of the local native population of Iberian ibex (Capra pyrenaica). Since then, additional outbreaks have been identified in several populations of ibex and other wild ungulate species throughout the country. Although the first epizootic outbreak in wildlife was attributed to the introduction of an infected herd of domestic goats, the origin and the cause of its persistence remain unclear. The main aims of this study are to understand (i) the number of Sarcoptes scabiei “strains” circulating in wild ruminant populations in Spain, and (ii) the molecular epidemiological relationships between S. scabiei and its hosts. Methods Ten Sarcoptes microsatellite markers were used to characterize the genetic structure of 266 mites obtained from skin scrapings of 121 mangy wild ruminants between 2011 and 2019 from 11 areas in Spain. Results Seventy-three different alleles and 37 private alleles were detected. The results of this study show the existence of three genetic strains of S. scabiei in the wild ruminant populations investigated. While two genetic clusters of S. scabiei were host- and geography-related, one cluster included multi-host mites deriving from geographically distant populations. Conclusions The molecular epidemiological study of S. scabiei in wild ruminants in Spain indicates that the spreading and persistence of the parasite may be conditioned by host species community composition and the permissiveness of each host population/community to the circulation of individual “strains,” among other factors. Wildlife–livestock interactions and the role of human-driven introduction or trade of wild and domestic animals should be better investigated to prevent further spread of sarcoptic mange in as yet unaffected natural areas of the Iberian Peninsula.

scholarly journals Parasite induced mortality is context dependent in Atlantic salmon: insights from an individual-based model

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Knut Wiik Vollset
Keyword(s):  
Atlantic Salmon ◽  
Environmental Gradients ◽  
Population Level ◽  
Relative Effect ◽  
Host Population ◽  
Sea Lice ◽  
Fish Farms ◽  
Individual Based Model ◽  
Parasite Infestation ◽  
The Impact

AbstractAn individual-based model was parameterized to explore the impact of a crustacean ectoparasite (sea louse, Lepeophtheirus salmonis & Caligus spp.) on migrating Atlantic salmon smolt. The model explores how environmental and intrinsic factors can modulate the effect of sea lice on survival, growth and maturation of Atlantic salmon at sea. Relative to other effects, the parasite infestation pressure from fish farms and the encounter process emerge as the most important parameters. Although small variations in parasite-induced mortality may be masked by variable environmental effects, episodes of high infestation pressure from fish farms should be observable in wild populations of Atlantic salmon if laboratory studies accurately reflect the physiological effects of sea lice. Increases in temperature in the model negatively influenced fish survival by affecting the development time of the parasite at a rate that was not compensated for by the growth of the host. Discharge from rivers was parameterized to increase migration speed and influenced parasite induced mortality by decreasing time spent in areas with increased infestation pressure. Initial size and growth of the host was inversely related to the impact of the parasite because of size-dependent parasite-induced mortality in the early phase of migration. Overall, the model illustrates how environmental factors modulate effects on the host population by impacting either the parasite load or the relative effect of the parasite. The results suggest that linking population-level effects to parasite infestation pressure across climatic and environmental gradients may be challenging without correctly accounting for these effects.

scholarly journals Resource fluctuations inhibit the reproduction and virulence of the human parasite Schistosoma mansoni in its snail intermediate host

2020 ◽  
Vol 287 (1919) ◽  
pp. 20192446
Author(s):  
David J. Civitello ◽  
Lucy H. Baker ◽  
Selvaganesh Maduraiveeran ◽  
Rachel B. Hartman
Keyword(s):  
Schistosoma Mansoni ◽  
Intermediate Host ◽  
Population Level ◽  
Host Population ◽  
Environmental Drivers ◽  
Bioenergetic Model ◽  
Snail Intermediate Host ◽  
Human Parasite ◽  
Infection Dynamics ◽  
Periodic Starvation

Resource availability can powerfully influence host–parasite interactions. However, we currently lack a mechanistic framework to predict how resource fluctuations alter individual infection dynamics. We address this gap with experiments manipulating resource supply and starvation for a human parasite, Schistosoma mansoni , and its snail intermediate host to test a hypothesis derived from mechanistic energy budget theory: resource fluctuations should reduce schistosome reproduction and virulence by inhibiting parasite ingestion of host biomass. Low resource supply caused hosts to remain small, reproduce less and produce fewer human-infectious cercariae. Periodic starvation also inhibited cercarial production and prevented infection-induced castration. The periodic starvation experiment also revealed substantial differences in fit between two bioenergetic model variants, which differ in their representation of host starvation. Simulations using the best-fit parameters of the winning model suggest that schistosome performance substantially declines with resource fluctuations with periods greater than 7 days. These experiments strengthen mechanistic theory, which can be readily scaled up to the population level to understand key feedbacks between resources, host population dynamics, parasitism and control interventions. Integrating resources with other environmental drivers of disease in an explicit bioenergetic framework could ultimately yield mechanistic predictions for many disease systems.

ASPECTS OF THE INTERACTION BETWEEN A CHALCID PARASITE AND ITS ALEURODID HOST

1967 ◽  
Vol 45 (4) ◽  
pp. 539-578 ◽  
Author(s):  
T. Burnett
Keyword(s):  
Larval Mortality ◽  
Trialeurodes Vaporariorum ◽  
Host Population ◽  
Population Variation ◽  
Encarsia Formosa ◽  
Greenhouse Whitefly ◽  
Parasite Abundance ◽  
Tomato Plants ◽  
Host Mortality ◽  
Dominant Process

Three populations of the greenhouse whitefly, Trialeurodes vaporariorum, and its chalcid parasite Encarsia formosa were propagated each year for three consecutive years on tomato plants in the greenhouse. The abundance of the host and parasite species fluctuated either with peaks of increasing amplitude, with peaks of decreasing amplitude, or with irregular peaks. The dominant process in the interaction was the occurrence of two qualitatively different types of host larval mortality: (a) parasitization, and (b) almost immediate killing after attack by adult parasites. Fluctuations in host and parasite abundance resulted from the almost immediate killing of small host larvae and the death of the short-lived adult parasites. The parasite population tended to destroy similar percentages of host populations of different densities but host mortality was also related to the age structure of the host population. Variation in host reproduction, caused by differences in rearing temperature and by seasonal variation in the physical environment, influenced host and parasite densities.

scholarly journals Synthesizing within-host and population-level selective pressures on viral populations: the impact of adaptive immunity on viral immune escape

2010 ◽  
Vol 7 (50) ◽  
pp. 1311-1318 ◽  
Author(s):  
Igor Volkov ◽  
Kim M. Pepin ◽  
James O. Lloyd-Smith ◽  
Jayanth R. Banavar ◽  
Bryan T. Grenfell
Keyword(s):  
Evolutionary Dynamics ◽  
Immune Escape ◽  
Adaptive Immune Response ◽  
Population Level ◽  
Analytical Framework ◽  
Host Population ◽  
Host Immunity ◽  
Host Cells ◽  
Susceptible Host ◽  
The Impact

The evolution of viruses to escape prevailing host immunity involves selection at multiple integrative scales, from within-host viral and immune kinetics to the host population level. In order to understand how viral immune escape occurs, we develop an analytical framework that links the dynamical nature of immunity and viral variation across these scales. Our epidemiological model incorporates within-host viral evolutionary dynamics for a virus that causes acute infections (e.g. influenza and norovirus) with changes in host immunity in response to genetic changes in the virus population. We use a deterministic description of the within-host replication dynamics of the virus, the pool of susceptible host cells and the host adaptive immune response. We find that viral immune escape is most effective at intermediate values of immune strength. At very low levels of immunity, selection is too weak to drive immune escape in recovered hosts, while very high levels of immunity impose such strong selection that viral subpopulations go extinct before acquiring enough genetic diversity to escape host immunity. This result echoes the predictions of simpler models, but our formulation allows us to dissect the combination of within-host and transmission-level processes that drive immune escape.

scholarly journals Indigenous People in Aotearoa New Zealand are Overrepresented in Cannabis Convictions

2021 ◽  
Author(s):  
Damian Scarf ◽  
Wetini Atutahi Rapana ◽  
Taylor Winter ◽  
Benjamin Riordan ◽  
Ririwai Fox ◽  
...  
Keyword(s):  
New Zealand ◽  
Indigenous People ◽  
No Reduction ◽  
Population Level ◽  
Law Reform ◽  
Marginal Effect ◽  
Data Infrastructure ◽  
National Statistics ◽  
Aotearoa New Zealand ◽  
Level Data

Background: Previous work has demonstrated that cannabis laws have had a disproportionate impact on Māori, the Indigenous people of Aotearoa New Zealand. In an attempt to address this bias, the New Zealand Government amended cannabis laws in 2019, providing police with the power to determine whether a health-centred approach would be more beneficial than a conviction. In the current study, we use population level data to assess whether this law change has ameliorated the bias in cannabis convictions for Māori.Methods: Data were drawn from the Integrated Data Infrastructure (IDI), a large government database hosted by Aotearoa New Zealand’s national statistics office. After constructing the population in the IDI, and filtering down to those who 1) were between 18 and 65, 2) were Māori or Pākehā and, 3) had any cannabis charges that proceeded to the courts, we had a sample of over 2,000 individuals.Results: Māori ethnicity was a significant predictor of the likelihood of receiving a cannabis conviction for Māori males, with a marginal effect for Māori females. Further, there was no reduction in the number of cannabis charges before vs. after the amendment to cannabis laws.Conclusion: The current study demonstrates that the 2019 amendment has not ameliorated the bias in cannabis convictions for Māori. Given this, the New Zealand Government must follow other countries around the world and move forward on cannabis law reform.

scholarly journals Susceptible host availability modulates climate effects on dengue dynamics

2019 ◽  
Author(s):  
Nicole Nova ◽  
Ethan R. Deyle ◽  
Marta S. Shocket ◽  
Andrew J. MacDonald ◽  
Marissa L. Childs ◽  
...  
Keyword(s):  
Disease Transmission ◽  
Population Level ◽  
Host Population ◽  
Interactive Effects ◽  
Climate Data ◽  
Negative Effects ◽  
Susceptible Host ◽  
Susceptible Population ◽  
Incidence Data ◽  
Dengue Transmission

AbstractExperiments and models suggest that climate affects mosquito-borne disease transmission. However, disease transmission involves complex nonlinear interactions between climate and population dynamics, which makes detecting climate drivers at the population level challenging. By analyzing incidence data, estimated susceptible population size, and climate data with methods based on nonlinear time series analysis (collectively referred to as empirical dynamic modeling), we identified drivers and their interactive effects on dengue dynamics in San Juan, Puerto Rico. Climatic forcing arose only when susceptible availability was high: temperature and rainfall had net positive and negative effects, respectively. By capturing mechanistic, nonlinear, and context-dependent effects of population susceptibility, temperature, and rainfall on dengue transmission empirically, our model improves forecast skill over recent, state-of-the-art models for dengue incidence. Together, these results provide empirical evidence that the interdependence of host population susceptibility and climate drive dengue dynamics in a nonlinear and complex, yet predictable way.

scholarly journals A review of mathematical models of influenza A infections within a host or cell culture: lessons learned and challenges ahead

2021 ◽  
Author(s):  
Catherine A. A. Beauchemin ◽  
Andreas Handel
Keyword(s):  
Public Health ◽  
Cell Culture ◽  
Mathematical Models ◽  
Influenza A ◽  
Influenza Infection ◽  
Population Level ◽  
Host Population ◽  
Lessons Learned ◽  
Infection Dynamics ◽  
Individual Host

Most mathematical models used to study the dynamics of influenza A have thus far focused on the between-host population level, with the aim to inform public health decisions regarding issues such as drug and social distancing intervention strategies, antiviral stockpiling or vaccine distribution. Here, we investigate mathematical modeling of influenza infection spread at a different scale; namely that occurring within an individual host or a cell culture. We review the models that have been developed in the last decades and discuss their contributions to our understanding of the dynamics of influenza infections. We review kinetic parameters (e.g., viral clearance rate, lifespan of infected cells) and values obtained through fitting mathematical models, and contrast them with values obtained directly from experiments. We explore the symbiotic role of mathematical models and experimental assays in improving our quantitative understanding of influenza infection dynamics. We also discuss the challenges in developing better, more comprehensive models for the course of influenza infections within a host or cell culture. Finally, we explain the contributions of such modeling efforts to important public health issues, and suggest future modeling studies that can help to address additional questions relevant to public health.

The population dynamics of competition between parasites

Parasitology ◽  
1985 ◽  
Vol 91 (2) ◽  
pp. 317-347 ◽  
Author(s):  
A. P. Dobson
Keyword(s):  
Population Dynamics ◽  
Parasite Species ◽  
Interference Competition ◽  
Population Level ◽  
Experimental Tests ◽  
Theoretical Models ◽  
Control Agent ◽  
Host Population ◽  
Free Living ◽  
The Impact

A number of published studies of competition between parasite species are examined and compared. It is suggested that two general levels of interaction are discernible: these correspond to the two levels of competition recognized by workers studying free-living animals and plants: ‘exploitation’ and ‘interference’ competition. The former may be defined as the joint utilization of a host species by two or more parasite species, while the latter occurs when antagonistic mechanisms are utilized by one species either to reduce the survival or fecundity of a second species or to displace it from a preferred site of attachment. Data illustrating both levels of interaction are collated from a survey of the published literature and these suggest that interference competition invariably operates asymmetrically. The data are also used to estimate a number of population parameters which are important in determining the impact of competition at the population level. Theoretical models of host-parasite associations for both classes of competition are used to examine the expected patterns of population dynamics that will be exhibited by simple two-species communities of parasites that utilize the same host population. The analysis suggests that the most important factor allowing competing species of parasites to coexist is the statistical distribution of the parasites within the host population. A joint stable equilibrium should be possible if both species are aggregated in their distribution. The size of the parasite burdens at equilibrium is then determined by other life-history parameters such as pathogenicity, rates of resource utilization and antagonistic ability. Comparison of these theoretical expectations with a variety of sets of empirical data forms the basis for a discussion about the importance of competition in natural parasite populations. The models are used to assess quantitatively the potential for using competing parasite species as biological control agents for pathogens of economic or medical importance. The most important criterion for identifying a successful control agent is an ability to infect a high proportion of the host population. If such a parasite species also exhibits an intermediate level of pathology or an efficient ability to utilize shared common resources, antagonistic interactions between the parasite species contribute only secondarily to the success of the control. Competition in parasites is compared with competition in free-living animals and plants. The comparison suggests further experimental tests which may help to assess the importance of competition in determining the structure of more complex parasite-host communities.

scholarly journals Host Genotype and Precipitation Influence of Fungal Endophyte Symbiosis and Mycotoxin Abundance in a Locoweed

2019 ◽  
Vol 20 (21) ◽  
pp. 5285
Author(s):  
Wei He ◽  
Linwei Guo ◽  
Lei Wang ◽  
Qianqian Zhao ◽  
Lizhu Guo ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Geographical Location ◽  
Population Level ◽  
Fungal Endophyte ◽  
Host Population ◽  
Host Genotype ◽  
Symbiotic Interactions ◽  
Naturally Occurring ◽  
Endophyte Infection ◽  
Host Genetic

Many plant endophytes produce mycotoxins, but how host genetic variation influences endophyte colonization and mycotoxin production under natural conditions is poorly understood. This interaction has not been fully considered in many previous studies which used controlled experiments with agronomic or model plant species. Here, we investigated this interaction in a naturally occurring forb (a locoweed species) Oxytropis ochrocephala, its symbiotic endophyte Alternaria oxytropis, and the mycotoxin swainsonine. Host genetic variation was characterized by microsatellite markers. Endophyte infection rate and swainsonine levels were determined by PCR and HPLC, respectively. Genetic markers defined two distinct host populations and revealed that host genetics were significantly correlated with geographical location, elevation, and precipitation. As the host diverged, symbiotic interactions were reduced or failed to produce detectable swainsonine in one host population. Host genotype and precipitation had a significant impact in shaping swainsonine production at the population level. This study highlights the effect of host genotype in influencing this interaction in locoweeds.

Sign in / Sign up

Export Citation Format

Share Document