Interplays of a waterborne disease model linking within- and between- host dynamics with waning vaccine-induced immunity

In this paper, we propose a multi-scale waterborne disease model and are concerned with a heterogenous process of waning vaccine-induced immunity. A completely nested rule has been adopted to link the within- and between-host systems. We prove the existence, positivity and asymptotical smoothness of the between-host system. We derive the basic reproduction numbers associated with the two-scale system in explicit forms, which completely determine the behavior of each system. Uncertainty analysis reveals the trade-offs of the kinetics of the within-host system and the transmission of the between-host system. Numerical simulations suggest that the vaccine waning process plays a significant role in the estimation of the prevalence at population level. Furthermore, the environmental heterogeneity complicates the transmission patterns at the population level.

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A novel multi-scale immuno-epidemiological model of visceral leishmaniasis in dogs

BIOMATH ◽

10.11145/j.biomath.2019.01.026 ◽

2019 ◽

Vol 8 (1) ◽

pp. 1901026 ◽

Cited By ~ 1

Author(s):

Jonathan Shane Welker ◽

Maia Martcheva

Keyword(s):

Visceral Leishmaniasis ◽

Population Level ◽

Endemic Equilibrium ◽

Epidemiological Model ◽

Published Data ◽

Host System ◽

Multi Scale ◽

Existence And Stability ◽

Tropical Climates ◽

Stability Results

Leishmaniasis is a neglected and emerging disease prevalent in Mediterranean and tropical climates. As such, the study and development of new models are of increasing importance. We introduce a new immuno-epidemiological model of visceral leishmaniasis in dogs. The within-host system is based on previously collected and published data, showing the movement and proliferation of the parasite in the skin and the bone-marrow, as well as the IgG response. The between-host system structures the infected individuals in time-since-infection and is of vector-host type. The within-host system has a parasite-free equilibrium and at least one endemic equilibrium, consistent with the fact that infected dogs do not recover without treatment. We compute the basic reproduction number R0 of the immuno-epidemiological model and provide the existence and stability results of the population-level disease-free equilibrium. Additionally, we prove existence of an unique endemic equilibrium when R0 > 1, and evidence of backward bifurcation and existence of multiple endemic equilibria when R0 < 1.

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Comparative cost-effectiveness of SARS-CoV-2 vaccine dose fractionation in India: a modelling study

10.21203/rs.3.rs-855843/v1 ◽

2021 ◽

Author(s):

Zhanwei Du ◽

Benjamin Cowling ◽

Lin Wang ◽

Abhishek Pandey ◽

Wey Wen Lim ◽

...

Keyword(s):

Vaccine Dose ◽

Vaccination Strategy ◽

Population Level ◽

Cost Effective ◽

Dose Fractionation ◽

Scale Model ◽

Effective Strategy ◽

Individual Level ◽

Multi Scale ◽

Reproduction Numbers

Abstract Given constrained vaccine supplies globally, fractionation of vaccine doses may be an effective strategy for reducing disease and healthcare burdens, even with the emergence of COVID-19 variants. Using a multi-scale model that incorporates population-level transmission and individual-level vaccination, we estimate the costs associated with hospitalization, vaccine costs, and the economic benefit of reducing COVID-19 deaths associated with dose-fractionation strategies. Assuming a willingness-to-pay of US$10,517 per averted year of life lost (YLL) and a price of $12 per vaccine, under various transmission scenarios, with effective reproduction numbers ranging from 1.1 to 5.0 and with vaccine efficacy against transmission from 52% to 91%, the optimal vaccination strategy would always involve fractional doses of vaccines. Vaccine dose fractionation is a cost-effective strategy for mitigating the COVID-19 pandemic and could save a large number of lives, even after the emergence of variants with higher transmissibility.

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A synthesis of scale-dependent ecology of the endangered mountain caribou in British Columbia, Canada

Rangifer ◽

10.7557/2.28.1.150 ◽

2008 ◽

Vol 28 (1) ◽

pp. 33

Author(s):

Robert Serrouya ◽

Bruce N. McLellan ◽

Clayton D. Apps ◽

Heiko U. Wittmer

Keyword(s):

British Columbia ◽

Rangifer Tarandus ◽

Spatial Scales ◽

Management Strategies ◽

Population Level ◽

Limiting Factors ◽

Conservation Strategies ◽

Integrative Approach ◽

Rangifer Tarandus Caribou ◽

Multi Scale

Mountain caribou are an endangered ecotype of woodland caribou (Rangifer tarandus caribou) that live in highprecipitation, mountainous ecosystems of southeastern British Columbia and northern Idaho. The distribution and abundance of these caribou have declined dramatically from historical figures. Results from many studies have indicated that mountain caribou rely on old conifer forests for several life-history requirements including an abundance of their primary winter food, arboreal lichen, and a scarcity of other ungulates and their predators. These old forests often have high timber value, and understanding mountain caribou ecology at a variety of spatial scales is thus required to develop effective conservation strategies. Here we summarize results of studies conducted at three different spatial scales ranging from broad limiting factors at the population level to studies describing the selection of feeding sites within seasonal home ranges of individuals. The goal of this multi-scale review is to provide a more complete picture of caribou ecology and to determine possible shifts in limiting factors across scales. Our review produced two important results. First, mountain caribou select old forests and old trees at all spatial scales, signifying their importance for foraging opportunities as well as conditions required to avoid alternate ungulates and their predators. Second, relationships differ across scales. For example, landscapes dominated by roads and edges negatively affect caribou survival, but appear to attract caribou during certain times of the year. This juxtaposition of fine-scale behaviour with broad-scale vulnerability to predation could only be identified through integrated multi-scale analyses of resource selection. Consequently we suggest that effective management strategies for endangered species require an integrative approach across multiple spatial scales to avoid a focus that may be too narrow to maintain viable populations. Abstract in Norwegian / Sammendrag:Skala-avhengig økologi og truet fjellvillrein i Britisk ColumbiaFjellvillreinen i de nedbørsrike fjellområdene i sørøstre Britisk Columbia og nordlige Idaho som er en truet økotype av skogsreinen (Rangifer tarandus caribou), har blitt kraftig redusert både i utbredelse og antall. Mange studier har vist at denne økotypen er avhengig av vinterføden hengelav i gammel barskog hvor det også er få andre klovdyr og dermed få predatorer. Slik skog er også viktige hogstområder, og å forstå økologien til fjellvillreinen i forskjellige skaleringer er derfor nødvendig for å utvikle forvaltningsstrategier som kan berge og ta vare på denne reinen. Artikkelen gir en oversikt over slike arbeider: fra studier av begrensende faktorer på populasjonsnivå til studier av sesongmessige beiteplasser på individnivå. Hensikten er å få frem et mer helhetlig perspektiv på fjellvillreinen og finne hvordan de begrensende faktorene varierer etter skaleringen som er benyttet i studiet. Oversikten vår frembragte to viktige resultater; 1) Uansett skalering så velger dyrene gammel skog og gamle trær. 2) Dyrenes bruk av et område kan variere med benyttet skalering, for eksempel vil landskap utbygd med veier og hogstflater være ufordelaktig for overlevelsen, men synes likevel å kunne tiltrekke fjellvillreinen til visse tider av året. Forholdet mellom atferd ut fra fin-skalering og stor-skalering sårbarhet hva gjelder predasjon, ville kun blitt avdekket ved flere-skaleringsanalyse av hvordan ressursene benyttes. Ut fra dette foreslår vi at forvaltningsstrategier for truete bestander som eksempelvis fjellvillreinen, må baseres på tilnærminger ut fra ulike skaleringer for å hindre at et for snevert perspektiv kan begrense muligheten for vedvarende levedyktighet.

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The case for Option B and Optional B+: Ensuring that South Africa’s commitment to eliminating mother-to-child transmission of HIV becomes a reality

Southern African Journal of HIV Medicine ◽

10.4102/sajhivmed.v13i4.112 ◽

2012 ◽

Vol 13 (4) ◽

pp. 178 ◽

Cited By ~ 3

Author(s):

D Besada ◽

G Van Cutsem ◽

E Goemaere ◽

N Ford ◽

H Bygrave ◽

...

Keyword(s):

South African ◽

Population Level ◽

World Health ◽

Mother To Child Transmission ◽

Child Transmission ◽

Trade Offs ◽

The Individual ◽

Mother To Child ◽

African Journal ◽

In Pregnancy

In a previous issue of the Southern African Journal of HIV Medicine, Pillay and Black summarised the trade-offs of the safety of efavirenz use in pregnancy (Pillay P, Black V. Safety, strength and simplicity of efavirenz in pregnancy. Southern African Journal of HIV Medicine 2012;13(1):28-33.). Highlighting the benefits of the World Health Organization’s proposed options for the prevention of mother-to-child transmission (PMTCT) of HIV, the authors argued that the South African government should adopt Option B as national PMTCT policy and pilot projects implementing Option B+ as a means of assessing the individual- and population-level effect of the intervention. We echo this call and further propose that the option to remain on lifelong antiretroviral therapy, effectively adopting PMTCT Option B+, be offered to pregnant women following the cessation of breastfeeding, for their own health, following the provision of counselling on associated benefits and risks. Here we highlight the benefits of Options B and B+.

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Reactive species from aviation in the multi-scale climate-chemistry model system MECO(n)

10.5194/dach2022-293 ◽

2021 ◽

Author(s):

Sigrun Matthes ◽

Patrick Peter ◽

Astrid Kerkweg ◽

Mariano Mertens ◽

Patrick Jöckel ◽

...

Keyword(s):

Measurement Data ◽

Reactive Species ◽

Model Representation ◽

Atmospheric Composition ◽

Systematic Evaluation ◽

High Temporal Resolution ◽

Aircraft Measurements ◽

Mitigation Options ◽

Multi Scale ◽

Trade Offs

Aviation aims to reduce its climate impact by identifying promising mitigation options which are able to reduce the overall climate effects of aviation considering CO2 and non-CO2 effects. While aiming to identify fuel optimal trajectories, aviation also aims to reduce the non-CO2 effects comprising NOx-induced changes of atmospheric ozone and methane. Here climate-chemistry models are required which are able to quantify perturbations in atmospheric composition of reactive species (NOx, O3) and the associated radiative forcings of aviation emissions relying on advanced modelling capabilities, realistic emission inventory data and global-scale observational datasets from research infrastructures like IAGOS and DLR aircraft measurement campaign data. We use the multi-scale climate-chemistry MECO(n) system which is a &#8220;MESSy-&#64257;ed ECHAM and COSMO nested n-times&#8221;, relying on the Modular Earth Submodel System (MESSy) framework. For this purpose, both models have been equipped with the MESSy infrastructure, implying that the same process formulations (MESSy submodels) are available for both models. Modelled atmospheric distributions are systematically compared to observational data from aircraft measurements in the upper troposphere and lower stratosphere. Nudging of meteorology to ERA5 interim data, and special diagnostics available within the modular MESSy infrastructure are implemented in the numerical simulations. Online sampling along aircraft trajectories allows to extract model data with a high temporal resolution (MESSy submodel S4D), in order to evaluate model representation and key processes. Beyond systematic evaluation with IAGOS scheduled aircraft measurements, episodes will be evaluated where dedicated measurements from aircraft campaigns are available, comprising Spring 2014 (ML-CIRRUS campaign), early summer 2020 (Blue Sky campaign) and summer 2021 (Cirrus-HL campaign). Our analysis of reactive species, NOy and ozone, identifies those weather pattern and synoptic situations where aviation contributes strong signals, resulting in recommendations on measurement strategies to detect aviation signal in the atmosphere. We evaluate model representation of the NOx-induces effect on radiatively active species ozone and methane in both model instances, ECHAM5 and COSMO. This is key for advancing the scientific understanding of NOx-induced effects from aviation which is required in order to quantify potential compensation and trade-offs when identifying robust mitigation options for sustainable aviation. This project has received funding from the European Union&#8217;s Horizon 2020 research and innovation programme under grant agreement No 875036 (ACACIA, Advancing the Science for Aviation and Climate) and has been supported by the DLR-Projekt Eco2Fly. This work uses measurement data from the European Research Infrastructure IAGOS/CARIBIC. High-Performance Super Computing simulations have been performed by the Deutsches Klima-Rechenzentrum (DKRZ, Hamburg) and the Leibniz-Rechenzentrum (LRZ, M&#252;nchen).

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Community Ecology of Stream Fishes: Concepts, Approaches, and Techniques

Community Ecology of Stream Fishes: Concepts, Approaches, and Techniques ◽

10.47886/9781934874141.ch10 ◽

2010 ◽

Keyword(s):

Great Plains ◽

Life Histories ◽

Environmental Heterogeneity ◽

Environmental Variability ◽

Spatial Scales ◽

Stream Fish ◽

Metapopulation Dynamics ◽

Stream Fishes ◽

Spatial And Temporal Scales ◽

Trade Offs

Abstract.—Stream fishes carry out their life histories across broad spatial and temporal scales, leading to spatially structured populations. Therefore, incorporating metapopulation dynamics into models of stream fish populations may improve our ability to understand mechanisms regulating them. First, we reviewed empirical research on metapopulation dynamics in the stream fish ecology literature and found 31 papers that used the metapopulation framework. The majority of papers applied no specific metapopulation model, or included space only implicitly. Although parameterization of spatially realistic models is challenging, we suggest that stream fish ecologists should incorporate space into models and recognize that metapopulation types may change across scales. Second, we considered metacommunity theory, which addresses how trade-offs among dispersal, environmental heterogeneity, and biotic interactions structure communities across spatial scales. There are no explicit tests of metacommunity theory using stream fishes to date, so we used data from our research in a Great Plains stream to test the utility of these paradigms. We found that this plains fish metacommunity was structured mainly by spatial factors related to dispersal opportunity and, to a lesser extent, by environmental heterogeneity. Currently, metacommunity models are more heuristic than predictive. Therefore, we propose that future stream fish metacommunity research should focus on developing testable hypotheses that incorporate stream fish life history attributes, and seasonal environmental variability, across spatial scales. This emerging body of research is likely to be valuable not only for basic stream fish ecological research, but also multispecies conservation and management.

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Transmission heterogeneities, kinetics, and controllability of SARS-CoV-2

Science ◽

10.1126/science.abe2424 ◽

2020 ◽

pp. eabe2424 ◽

Cited By ~ 8

Author(s):

Kaiyuan Sun ◽

Wei Wang ◽

Lidong Gao ◽

Yan Wang ◽

Kaiwei Luo ◽

...

Keyword(s):

Social Interactions ◽

Population Level ◽

Transmission Risk ◽

Contact Tracing ◽

Symptom Presentation ◽

Secondary Infections ◽

The Family ◽

Infectious Disease Dynamics ◽

Kinetics Of

A long-standing question in infectious disease dynamics concerns the role of transmission heterogeneities, driven by demography, behavior and interventions. Based on detailed patient and contact tracing data in Hunan, China we find 80% of secondary infections traced back to 15% of SARS-CoV-2 primary infections, indicating substantial transmission heterogeneities. Transmission risk scales positively with the duration of exposure and the closeness of social interactions and is modulated by demographic and clinical factors. The lockdown period increases transmission risk in the family and households, while isolation and quarantine reduce risks across all types of contacts. The reconstructed infectiousness profile of a typical SARS-CoV-2 patient peaks just before symptom presentation. Modeling indicates SARS-CoV-2 control requires the synergistic efforts of case isolation, contact quarantine, and population-level interventions, owing to the specific transmission kinetics of this virus.

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