scholarly journals Implications of asymptomatic carriers for infectious disease transmission and control

2018 ◽  
Vol 5 (2) ◽  
pp. 172341 ◽  
Author(s):  
Rebecca H. Chisholm ◽  
Patricia T. Campbell ◽  
Yue Wu ◽  
Steven Y. C. Tong ◽  
Jodie McVernon ◽  
...  
Keyword(s):  
Disease Transmission ◽  
Model Parameters ◽  
Model Structure ◽  
Infectious Disease Transmission ◽  
Asymptomatic Carriers ◽  
Effective Interventions ◽  
History Of ◽  
And Control ◽  
Selection Of

For infectious pathogens such as Staphylococcus aureus and Streptococcus pneumoniae , some hosts may carry the pathogen and transmit it to others, yet display no symptoms themselves. These asymptomatic carriers contribute to the spread of disease but go largely undetected and can therefore undermine efforts to control transmission. Understanding the natural history of carriage and its relationship to disease is important for the design of effective interventions to control transmission. Mathematical models of infectious diseases are frequently used to inform decisions about control and should therefore accurately capture the role played by asymptomatic carriers. In practice, incorporating asymptomatic carriers into models is challenging due to the sparsity of direct evidence. This absence of data leads to uncertainty in estimates of model parameters and, more fundamentally, in the selection of an appropriate model structure. To assess the implications of this uncertainty, we systematically reviewed published models of carriage and propose a new model of disease transmission with asymptomatic carriage. Analysis of our model shows how different assumptions about the role of asymptomatic carriers can lead to different conclusions about the transmission and control of disease. Critically, selecting an inappropriate model structure, even when parameters are correctly estimated, may lead to over- or under-estimates of intervention effectiveness. Our results provide a more complete understanding of the role of asymptomatic carriers in transmission and highlight the importance of accurately incorporating carriers into models used to make decisions about disease control.

scholarly journals Schistosomiasis: from established diagnostic assays to emerging micro/nanotechnology-based rapid field testing for clinical management and epidemiology

2019 ◽  
Vol 3 (1) ◽  
pp. 439-458 ◽  
Author(s):  
Maurice Mutro Nigo ◽  
Georgette Salieb-Beugelaar ◽  
Manuel Battegay ◽  
Peter Odermatt ◽  
Patrick Hunziker
Keyword(s):  
Point Of Care ◽  
Field Testing ◽  
Detection Methods ◽  
Low Grade ◽  
Analytical Strategy ◽  
Diagnostic Assays ◽  
And Control ◽  
Analytical Platforms ◽  
Selection Of

Schistosomiasis is a neglected invasive worm disease with a huge disease burden in developing countries, particularly in children, and is seen increasingly in non-endemic regions through transfer by travellers, expatriates, and refugees. Undetected and untreated infections may be responsible for the persistence of transmission. Rapid and accurate diagnosis is the key to treatment and control. So far, parasitological detection methods remain the cornerstone of Schistosoma infection diagnosis in endemic regions, but conventional tests have limited sensitivity, in particular in low-grade infection. Recent advances contribute to improved detection in clinical and field settings. The recent progress in micro- and nanotechnologies opens a road by enabling the design of new miniaturized point-of-care devices and analytical platforms, which can be used for the rapid detection of these infections. This review starts with an overview of currently available laboratory tests and their performance and then discusses emerging rapid and micro/nanotechnologies-based tools. The epidemiological and clinical setting of testing is then discussed as an important determinant for the selection of the best analytical strategy in patients suspected to suffer from Schistosoma infection. Finally, it discusses the potential role of advanced technologies in the setting near to disease eradication is examined.

scholarly journals The importance of vegetation to understand terrestrial water storage variations

2021 ◽  
Author(s):  
Tina Trautmann ◽  
Sujan Koirala ◽  
Nuno Carvalhais ◽  
Andreas Güntner ◽  
Martin Jung
Keyword(s):  
Soil Moisture ◽  
Large Scale ◽  
Water Storage ◽  
Model Parameters ◽  
Intermediate Water ◽  
Model Structure ◽  
Hydrological Models ◽  
Terrestrial Water Storage ◽  
Terrestrial Water

Abstract. So far, various studies aimed at decomposing the integrated terrestrial water storage variations observed by satellite gravimetry (GRACE, GRACE-FO) with the help of large-scale hydrological models. While the results of the storage decomposition depend on model structure, little attention has been given to the impact of the way how vegetation is represented in these models. Although vegetation structure and activity represent the crucial link between water, carbon and energy cycles, their representation in large-scale hydrological models remains a major source of uncertainty. At the same time, the increasing availability and quality of Earth observation-based vegetation data provide valuable information with good prospects for improving model simulations and gaining better insights into the role of vegetation within the global water cycle. In this study, we use observation-based vegetation information such as vegetation indices and rooting depths for spatializing the parameters of a simple global hydrological model to define infiltration, root water uptake and transpiration processes. The parameters are further constrained by considering observations of terrestrial water storage anomalies (TWS), soil moisture, evapotranspiration (ET) and gridded runoff (Q) estimates in a multi-criteria calibration approach. We assess the implications of including vegetation on the simulation results, with a particular focus on the partitioning between water storage components. To isolate the effect of vegetation, we compare a model experiment with vegetation parameters varying in space and time to a baseline experiment in which all parameters are calibrated as static, globally uniform values. Both experiments show good overall performance, but including vegetation data led to even better performance and more physically plausible parameter values. Largest improvements regarding TWS and ET were seen in supply-limited (semi-arid) regions and in the tropics, whereas Q simulations improve mainly in northern latitudes. While the total fluxes and storages are similar, accounting for vegetation substantially changes the contributions of snow and different soil water storage components to the TWS variations, with the dominance of an intermediate water pool that interacts with the fast plant accessible soil moisture and the delayed water storage. The findings indicate the important role of deeper moisture storages as well as groundwater-soil moisture-vegetation interactions as a key to understanding TWS variations. We highlight the need for further observations to identify the adequate model structure rather than only model parameters for a reasonable representation and interpretation of vegetation-water interactions.

scholarly journals The Role of Vertical Transmission in the Control of Dengue Fever

2019 ◽  
Vol 16 (5) ◽  
pp. 803 ◽  
Author(s):  
David Murillo ◽  
Anarina Murillo ◽  
Sunmi Lee
Keyword(s):  
Dengue Fever ◽  
Vertical Transmission ◽  
Disease Transmission ◽  
Control Function ◽  
Infected Mosquito ◽  
Effective Control ◽  
Control Policies ◽  
Effective Interventions ◽  
Endemic Strain

In this work, a two-strain dengue model with vertical transmission in the mosquito population is considered. Although vertical transmission is often ignored in models of dengue fever, we show that effective control of an outbreak of dengue can depend on whether or not the vertical transmission is a significant mode of disease transmission. We model the effect of a control strategy aimed at reducing human-mosquito transmissions in an optimal control framework. As the likelihood of vertical transmission increases, outbreaks become more difficult and expensive to control. However, even for low levels of vertical transmission, the additional, uncontrolled, transmission from infected mosquito to eggs may undercut the effectiveness of any control function. This is of particular importance in regions where existing control policies may be effective and the endemic strain does not exhibit vertical transmission. If a novel strain that does exhibit vertical transmission invades, then existing, formerly effective, control policies may no longer be sufficient. Therefore, public health officials should pay more attention to the role of vertical transmission for more effective interventions and policy.

scholarly journals Modeling the Effects of Spatial Heterogeneity and Seasonality on Guinea Worm Disease Transmission

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Anthony A. E. Losio ◽  
Steady Mushayabasa
Keyword(s):  
Spatial Heterogeneity ◽  
Vector Control ◽  
Disease Transmission ◽  
Disease Surveillance ◽  
Neglected Tropical Diseases ◽  
South Sudan ◽  
Model Parameters ◽  
Guinea Worm ◽  
Infection Dynamics ◽  
And Control

Guinea worm disease is one of the neglected tropical diseases that is on the verge of elimination. Currently the disease is endemic in four countries, namely, Ethiopia, Mali, Chad, and South Sudan. Prior studies have demonstrated that climate factors and limited access to safe drinking water have a significant impact on transmission and control of Guinea worm disease. In this paper, we present a new mathematical model to understand the transmission dynamics of Guinea worm disease in South Sudan. The model incorporates seasonal variations, educational campaigns, and spatial heterogeneity. Both qualitative and quantitative analysis of the model have been carried out. Utilizing Guinea worm disease surveillance data of South Sudan (2007-2013) we estimate the model parameters. Meanwhile, we perform an optimal control study to evaluate the implications of vector control on long-term Guinea worm infection dynamics. Our results demonstrate that vector control could play a significant role on Guinea worm disease eradication.

scholarly journals The Social Construction of Historical Traumas: The Polish Experience of the Uses of History in an Intelligentsia-dominated Polity

2020 ◽  
Vol 28 (6) ◽  
pp. 911-931
Author(s):  
Tomasz Zarycki ◽  
Tomasz Warczok
Keyword(s):  
Social Construction ◽  
Historical Narrative ◽  
The West ◽  
Specific Nature ◽  
Polish Experience ◽  
The Social ◽  
History Of ◽  
Historical Identity ◽  
And Control

The article argues that Poland’s mainstream national historical narrative, at least as far as the last two centuries of history of the country is concerned, is full of ‘traumatic’ motives which are regularly used and developed in diverse current political and intellectual contexts. Polish history is imagined to a large extent as an endless chain of 200 years of suffering, caused, among other things, by occupations, wars and exploitation, which are usually seen as not fully recognized in other countries, in particular in the West. The article attempts first of all to explain this specific nature of Poland’s historical identity by the privileged role of the intelligentsia, understood as a specific type of elite based on possession and control of cultural capital. It reconstructs the historical rise of the intelligentsia and its impact on the mainstream narrative in question, pointing to a selective choice of potential ‘traumas’ which are assigned a national status. They may be seen as tools to build positions in what can be called the Polish ‘field of power’, to use the notion coined by Pierre Bourdieu. The particular configuration and recent history of the field of power in Poland is reconstructed in order to explain different strategies of what can be called the social and political construction of historical traumas in Poland.

Motives for ‘Disappearances’ in Argentina, Chile and Uruguay in the 1970s

1995 ◽  
Vol 13 (1) ◽  
pp. 51-64 ◽  
Author(s):  
Wolfgang S. Heinz
Keyword(s):  
Armed Conflict ◽  
State Violence ◽  
Civilian Control ◽  
Internal Security ◽  
And Control ◽  
The Military ◽  
Good And Evil ◽  
Point Of Departure ◽  
Selection Of

The article looks at the motives of military governments in Argentina, Chile and Uruguay to introduce ‘disappearances’ as a new method to fight ‘subversion’ and thereby commit human rights violations. Five variables are taken as a point of departure, the country's previous experience with use of state violence, the selection of victims, the role of international public opinion, the selection of methods within the state and ideological factors. Among the key elements were in two countries the shift of responsibility for the use of violence to the military before the coup (except Chile), a lack of civilian control and influence in the formulation and control of internal security policies and an overwhelming, confused ideological definition in Argentina and in Chile (to a lesser degree in Uruguay) of the armed conflict as a war between good and evil and against World Communism which endangered the survival of the nation.

Continuity in change: A history of radio for national development

2019 ◽  
Vol 17 (2) ◽  
pp. 217-234
Author(s):  
Gilbert K. M. Tietaah ◽  
Margaret I. Amoakohene ◽  
Marquita S. Smith
Keyword(s):  
Communication Theory ◽  
National Development ◽  
Theory And Practice ◽  
Development Communication ◽  
Social Forces ◽  
Paradigm Shifts ◽  
Liberal Pluralism ◽  
History Of ◽  
And Control

In this article, we assert and demonstrate a particular and enduring adaptability of radio in tandem with observable temporal shifts in development communication theory and practice in Africa. Specifically, we use the historical research method to explore and explain the ideological discourses, polity contours and social forces that have overlain the role of radio as both an index and an instrument of development in Ghana. The evidence reveals that radio has transitioned through three key milestones in how the technology has been appropriated and applied to national development efforts: from transplantation, through transmission, to transaction. Each of these phases coincides, incidentally, with paradigm shifts in development communication theorizing: from modernization through diffusion to participation. They also coincide, broadly, with three distinctive epochs of ideological shifts in the historical accounting on radio for development in Ghana: from British imperial hegemony, through post-independence command-and-control, to contemporary liberal pluralism.

Body and law in late Anglo-Saxon England

1998 ◽  
Vol 27 ◽  
pp. 209-232 ◽  
Author(s):  
Katherine O'Brien O'Keeffe
Keyword(s):  
The Body ◽  
Anglo Saxon ◽  
Manuscript Production ◽  
History Of ◽  
The Subject ◽  
The Law ◽  
The Individual ◽  
And Control ◽  
Point Of Departure

This article explores some textual dimensions of what I argue is a crucial moment in the history of the Anglo-Saxon subject. For purposes of temporal triangulation, I would locate this moment between roughly 970 and 1035, though these dates function merely as crude, if potent, signposts: the years 970×973 mark the adoption of the Regularis concordia, the ecclesiastical agreement on the practice of a reformed (and markedly continental) monasticism, and 1035 marks the death of Cnut, the Danish king of England, whose laws encode a change in the understanding of the individual before the law. These dates bracket a rich and chaotic time in England: the apex of the project of reform, a flourishing monastic culture, efflorescence of both Latin and vernacular literatures, remarkable manuscript production, but also the renewal of the Viking wars that seemed at times to be signs of the apocalypse and that ultimately would put a Dane on the throne of England. These dates point to two powerful and continuing sets of interests in late Anglo-Saxon England, ecclesiastical and secular, monastic and royal, whose relationships were never simple. This exploration of the subject in Anglo-Saxon England as it is illuminated by the law draws on texts associated with each of these interests and argues their interconnection. Its point of departure will be the body – the way it is configured, regarded, regulated and read in late Anglo-Saxon England. It focuses in particular on the use to which the body is put in juridical discourse: both the increasing role of the body in schemes of inquiry and of punishment and the ways in which the body comes to be used to know and control the subject.

scholarly journals Investigating the Role of Environmental Transmission in COVID-19 Dynamics: A Mathematical Model Based Study

2020 ◽  
Author(s):  
Ibrahim M. ELmojtaba ◽  
Fatma Al-Musalhi ◽  
Asma Al-Ghassani ◽  
Nasser Al-Salti
Keyword(s):  
Mathematical Model ◽  
Disease Transmission ◽  
Reproduction Number ◽  
Equilibrium Points ◽  
Transmission Dynamics ◽  
Model Parameters ◽  
Environmental Transmission ◽  
Estimated Parameters ◽  
Existence And Stability

Abstract A mathematical model with environmental transmission has been proposed and analyzed to investigate its role in the transmission dynamics of the ongoing COVID-19 outbreak. Two expressions for the basic reproduction number R0 have been analytically derived using the next generation matrix method. The two expressions composed of a combination of two terms related to human to human and environment to human transmissions. The value of R0 has been calculated using estimated parameters corresponding to two datasets. Sensitivity analysis of the reproduction number to the corresponding model parameters has been carried out. Existence and stability analysis of disease free and endemic equilibrium points have been presented in relation with the obtained expressions of R0. Numerical simulations to demonstrate the effect of some model parameters related to environmental transmission on the disease transmission dynamics have been carried out and the results have been demonstrated graphically.

scholarly journals Aquaporins in regulation of plant protective responses to drought

2021 ◽  
Vol 78 (3) ◽  
pp. 221-234
Author(s):  
I.I. Ovrutska ◽  
Keyword(s):  
Transmembrane Proteins ◽  
Main Function ◽  
Adverse Conditions ◽  
Resistant Varieties ◽  
Regulation Of Metabolism ◽  
History Of ◽  
And Function ◽  
Selection Of ◽  
Integral Indicator

Plasmolemma permeability is an integral indicator of the functional state of plant cells under stress. Aquaporins (AQPs), specialized transmembrane proteins that form water channels and play an important role in the adaptation of plants to adverse conditions and, in particular, to lack or excess of water, are involved in the formation of the response to drought. The main function of AQPs is to facilitate the movement of water across cell membranes and maintain aqueous cell homeostasis. Under stressful conditions, there is both an increase and decrease in the expression of individual aquaporin genes. Analysis of the data revealed differences in the expression of AQPs genes in stable and sensitive plant genotypes. It turned out that aquaporins in different stress-resistant varieties of the same species also respond differently to drought. The review provides brief information on the history of the discovery of aquaporins, the structure and function of these proteins, summarizes the latest information on the role of aquaporins in the regulation of metabolism and the response of plants to stressors, with particular emphasis on aquaporins in drought protection. The discovery and study of AQPs expands the possibilities of using genetic engineering methods for the selection of new plant species, in particular, more resistant to drought and salinization of the soil, as well as to increase their productivity. The use of aquaporins in biotechnology to improve drought resistance of various species has many prospects.

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