scholarly journals Human mobility networks and persistence of rapidly mutating pathogens

2017 ◽  
Vol 4 (3) ◽  
pp. 160914 ◽  
Author(s):  
Alberto Aleta ◽  
Andreia N. S. Hisi ◽  
Sandro Meloni ◽  
Chiara Poletto ◽  
Vittoria Colizza ◽  
...  
Keyword(s):  
Phase Space ◽  
Disease Ecology ◽  
Large Scale ◽  
Human Mobility ◽  
Population Level ◽  
Infectious Period ◽  
Acquired Immunity ◽  
Heterogeneous Environment ◽  
Dynamical Regimes

Rapidly mutating pathogens may be able to persist in the population and reach an endemic equilibrium by escaping hosts’ acquired immunity. For such diseases, multiple biological, environmental and population-level mechanisms determine the dynamics of the outbreak, including pathogen's epidemiological traits (e.g. transmissibility, infectious period and duration of immunity), seasonality, interaction with other circulating strains and hosts’ mixing and spatial fragmentation. Here, we study a susceptible-infected-recovered-susceptible model on a metapopulation where individuals are distributed in sub-populations connected via a network of mobility flows. Through extensive numerical simulations, we explore the phase space of pathogen's persistence and map the dynamical regimes of the pathogen following emergence. Our results show that spatial fragmentation and mobility play a key role in the persistence of the disease whose maximum is reached at intermediate mobility values. We describe the occurrence of different phenomena including local extinction and emergence of epidemic waves, and assess the conditions for large-scale spreading. Findings are highlighted in reference to previous studies and to real scenarios. Our work uncovers the crucial role of hosts’ mobility on the ecological dynamics of rapidly mutating pathogens, opening the path for further studies on disease ecology in the presence of a complex and heterogeneous environment.

scholarly journals The interaction of seasonal forcing and immunity and the resonance dynamics of malaria

2009 ◽  
Vol 7 (43) ◽  
pp. 309-319 ◽  
Author(s):  
Dylan Z. Childs ◽  
Michael Boots
Keyword(s):  
Host Immunity ◽  
Dynamical Model ◽  
Infectious Period ◽  
Acquired Immunity ◽  
Disease Dynamics ◽  
Annual Cycles ◽  
Intrinsic Factors ◽  
Strong Seasonality

Theory has emphasized the importance of both intrinsic factors such as host immunity and extrinsic drivers such as climate in determining disease dynamics. In particular, seasonality may lead to multi-annual cycles in prevalence, but the likelihood of this depends on the role of acquired immunity. Some diseases including malaria have immunity that falls between the classic susceptible–infectious–removed and susceptible–infectious–susceptible models. Here, we investigate the general conditions promoting the subharmonic resonance behaviour that may lead to multi-annual cycles in a general malaria dynamical model. Utilizing two complementary approaches to bifurcation analyses, we show that resonance is promoted by processes shortening the length of the infectious period and that subharmonic cycles are favoured in situations with strong seasonality in transmission but at intermediate levels of endemicity. We discuss the implications of our results for understanding prevalence patterns in long-term malaria datasets from Kenya that show multi-annual cycles and one from Thailand that does not and discuss the possible implications of treatment.

scholarly journals Megacities as drivers of national outbreaks: the role of holiday travel in the spread of infectious diseases

2019 ◽  
Author(s):  
Ayesha S. Mahmud ◽  
Md. Iqbal Kabir ◽  
Kenth Engø-Monsen ◽  
Sania Tahmina ◽  
Baizid Khoorshid Riaz ◽  
...  
Keyword(s):  
Infectious Diseases ◽  
Large Scale ◽  
Disease Risk ◽  
Human Mobility ◽  
Mobile Phone Data ◽  
Dhaka City ◽  
Population Mobility ◽  
Time Data ◽  
The Impact

AbstractHuman mobility connects populations and can lead to large fluctuations in population density, both of which are important drivers of epidemics. Measuring population mobility during infectious disease outbreaks is challenging, but is a particularly important goal in the context of rapidly growing and highly connected urban centers in low and middle income countries, which can act to amplify and spread local epidemics nationally and internationally. Here, we combine estimates of population movement from mobile phone data for over 4 million subscribers in the megacity of Dhaka, Bangladesh, one of the most densely populated cities globally. We combine mobility data with epidemiological data from a household survey, to understand the role of population mobility on the spatial spread of the mosquito-borne virus chikungunya within and outside Dhaka city during a large outbreak in 2017. The peak of the 2017 chikungunya outbreak in Dhaka coincided with the annual Eid holidays, during which large numbers of people traveled from Dhaka to their native region in other parts of the country. We show that regular population fluxes around Dhaka city played a significant role in determining disease risk, and that travel during Eid was crucial to the spread of the infection to the rest of the country. Our results highlight the impact of large-scale population movements, for example during holidays, on the spread of infectious diseases. These dynamics are difficult to capture using traditional approaches, and we compare our results to a standard diffusion model, to highlight the value of real-time data from mobile phones for outbreak analysis, forecasting, and surveillance.

Wild Bird Populations in the Face of Disease

2021 ◽  
pp. 121-144
Author(s):  
Kathryn P. Huyvaert
Keyword(s):  
Population Dynamics ◽  
Disease Ecology ◽  
Population Level ◽  
Host Population ◽  
Infection Prevalence ◽  
Imperfect Detection ◽  
Statistical Parameters ◽  
Bird Populations ◽  
The Face

Parasites and pathogens typically have detectable negative fitness impacts on individual avian hosts, but the role of parasites in driving population dynamics is less straightforward. Questions about whether and under what conditions parasites influence host population dynamics have been long-standing in infectious disease ecology for many years. Understanding the role of parasites in host population dynamics requires estimating statistical parameters such as infection prevalence and host abundance at population scales. Mathematical approaches such as process-based models are also often used to simulate population-level dynamics of host and parasite interactions over time. This chapter first describes tools commonly used in disease ecology to estimate these key parameters, with a focus on accounting for imperfect detection of individual animals or their disease or infection status and mark-recapture approaches. Some of the mathematical approaches, including SIR models, network approaches, and agent-based models, that are commonly used to simulate and predict the population dynamics of host–parasite interactions are presented. Through a series of case studies, the chapter finishes by considering whether and under what conditions parasites affect the overall growth of populations, whether parasites have a tendency to cause cycles or to regulate populations of wild birds, and some examples of parasite-induced local extinctions.

scholarly journals Modelling cholera epidemics: the role of waterways, human mobility and sanitation

2011 ◽  
Vol 9 (67) ◽  
pp. 376-388 ◽  
Author(s):  
L. Mari ◽  
E. Bertuzzo ◽  
L. Righetto ◽  
R. Casagrandi ◽  
M. Gatto ◽  
...  
Keyword(s):  
Long Range ◽  
Large Scale ◽  
Human Mobility ◽  
Human Movement ◽  
Epidemiological Data ◽  
Long Distance ◽  
Regional Patterns ◽  
Spatially Explicit Model ◽  
Kwazulu Natal

We investigate the role of human mobility as a driver for long-range spreading of cholera infections, which primarily propagate through hydrologically controlled ecological corridors. Our aim is to build a spatially explicit model of a disease epidemic, which is relevant to both social and scientific issues. We present a two-layer network model that accounts for the interplay between epidemiological dynamics, hydrological transport and long-distance dissemination of the pathogen Vibrio cholerae owing to host movement, described here by means of a gravity-model approach. We test our model against epidemiological data recorded during the extensive cholera outbreak occurred in the KwaZulu-Natal province of South Africa during 2000–2001. We show that long-range human movement is fundamental in quantifying otherwise unexplained inter-catchment transport of V. cholerae , thus playing a key role in the formation of regional patterns of cholera epidemics. We also show quantitatively how heterogeneously distributed drinking water supplies and sanitation conditions may affect large-scale cholera transmission, and analyse the effects of different sanitation policies.

Making sense of the Global Coronavirus Data: The role of testing rates in understanding the pandemic and our exit strategy (Preprint)

2020 ◽  
Author(s):  
Rahul Potluri ◽  
Deepthi Lavu
Keyword(s):  
Large Scale ◽  
Population Level ◽  
Death Rates ◽  
Social Instability ◽  
Making Sense ◽  
Number Of Patients ◽  
The World ◽  
Inherent Case ◽  
Early Indication

BACKGROUND The Coronavirus disease 2019(COVID-19) outbreak has caused havoc across the world. Subsequently, research on COVID-19 has focused on number of cases and deaths and predicted projections have focused on these parameters. We propose that the number of tests performed is a very important denominator in understanding the COVID-19 data. OBJECTIVE We analysed the number of diagnostic tests performed in proportion to the number of cases and subsequently deaths across different countries and projected pandemic outcomes. METHODS We obtained real time COVID-19 data from the reference website Worldometer at 0900 BST on Saturday 4th April, 2020 and collated the information obtained on the top 50 countries with the highest number of COVID 19 cases. We analysed this data according to the number of tests performed as the main denominator. Country wise population level pandemic projections were extrapolated utilising three models - 1) inherent case per test and death per test rates at the time of obtaining the data (4/4/2020 0900 BST) for each country; 2) rates adjusted according to the countries who conducted at least 100000 tests and 3) rates adjusted according to South Korea. RESULTS We showed that testing rates impact on the number of cases and deaths and ultimately on future projections for the pandemic across different countries. CONCLUSIONS We found that countries with the highest testing rates per population have the lowest death rates and give us an early indication of an eventual COVID-19 mortality rate. It is only by continued testing on a large scale that will enable us to know if the increasing number of patients who are seriously unwell in hospitals across the world are the tip of the iceberg or not. Accordingly, obtaining this information through a rapid increase in testing globally is the only way which will enable us to exit the COVID-19 pandemic and reduce economic and social instability. CLINICALTRIAL Not applicable

scholarly journals Making sense of the Global Coronavirus Data: The role of testing rates in understanding the pandemic and our exit strategy

2020 ◽  
Author(s):  
Rahul Potluri ◽  
Deepthi Lavu
Keyword(s):  
Large Scale ◽  
Population Level ◽  
Death Rates ◽  
Social Instability ◽  
Making Sense ◽  
Number Of Patients ◽  
The World ◽  
Inherent Case ◽  
Early Indication

AbstractThe Coronavirus disease 2019(COVID-19) outbreak has caused havoc across the world. Subsequently, research on COVID-19 has focused on number of cases and deaths and predicted projections have focused on these parameters. We propose that the number of tests performed is a very important denominator in understanding the COVID-19 data. We analysed the number of diagnostic tests performed in proportion to the number of cases and subsequently deaths across different countries and projected pandemic outcomes.We obtained real time COVID-19 data from the reference website Worldometer at 0900 BST on Saturday 4th April, 2020 and collated the information obtained on the top 50 countries with the highest number of COVID 19 cases. We analysed this data according to the number of tests performed as the main denominator. Country wise population level pandemic projections were extrapolated utilising three models - 1) inherent case per test and death per test rates at the time of obtaining the data (4/4/2020 0900 BST) for each country; 2) rates adjusted according to the countries who conducted at least 100000 tests and 3) rates adjusted according to South Korea.We showed that testing rates impact on the number of cases and deaths and ultimately on future projections for the pandemic across different countries. We found that countries with the highest testing rates per population have the lowest death rates and give us an early indication of an eventual COVID-19 mortality rate. It is only by continued testing on a large scale that will enable us to know if the increasing number of patients who are seriously unwell in hospitals across the world are the tip of the iceberg or not. Accordingly, obtaining this information through a rapid increase in testing globally is the only way which will enable us to exit the COVID-19 pandemic and reduce economic and social instability.

scholarly journals Single Nanoparticle Tracking Reveals Efficient Long-Distance Undercurrent Transport above Swarming Bacteria

2019 ◽  
Author(s):  
Jingjing Feng ◽  
Zexin Zhang ◽  
Xiaodong Wen ◽  
Jianfeng Xue ◽  
Yan He
Keyword(s):  
High Speed ◽  
Large Scale ◽  
Fluid Phase ◽  
Population Level ◽  
Long Distance ◽  
Motile Cells ◽  
Large Step ◽  
Complex Fluid ◽  
Non Gaussian

AbstractFlagellated bacteria move collectively in a swirling pattern on agar surfaces immersed in a thin layer of viscous “swarm fluid”, but the role of this fluid in mediating the cooperation of the bacterial population is not well understood. Herein, we use gold nanorods (AuNRs) as single particle tracers to explore the spatiotemporal structure of the swarm fluid. We observed that individual AuNRs are transported in a plane of ~2 μm above the motile cells. They can travel for long distances (>700 μm) in a 2D plane at high speed (often >50 μm2/s) without interferences from bacterial movements. The particles are apparently lifted up and transported by collective mixing of the small vortices around bacteria during localized clustering and de-clustering of the motile cells, exhibiting superdiffusive and non-Gaussian characteristics with alternating large-step jumps and confined lingering. Their motions are consistent with the Lévy walk (LW) model, revealing efficient transport flows above swarms. These flows provide obstacle-free highways for long-range material transportations, shed light on how swarming bacteria perform population-level communications, and reveal the essential role of the fluid phase on the emergence of large-scale synergy. This approach is promising for probing complex fluid dynamics and transports in other collective systems.

scholarly journals Uncovering the socioeconomic facets of human mobility

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hugo Barbosa ◽  
Surendra Hazarie ◽  
Brian Dickinson ◽  
Aleix Bassolas ◽  
Adam Frank ◽  
...  
Keyword(s):  
Socioeconomic Status ◽  
Public Transportation ◽  
Large Scale ◽  
Human Mobility ◽  
Economic Status ◽  
Urban Infrastructure ◽  
Economic Systems ◽  
The Us ◽  
Low Levels

AbstractGiven the rapid recent trend of urbanization, a better understanding of how urban infrastructure mediates socioeconomic interactions and economic systems is of vital importance. While the accessibility of location-enabled devices as well as large-scale datasets of human activities, has fueled significant advances in our understanding, there is little agreement on the linkage between socioeconomic status and its influence on movement patterns, in particular, the role of inequality. Here, we analyze a heavily aggregated and anonymized summary of global mobility and investigate the relationships between socioeconomic status and mobility across a hundred cities in the US and Brazil. We uncover two types of relationships, finding either a clear connection or little-to-no interdependencies. The former tend to be characterized by low levels of public transportation usage, inequitable access to basic amenities and services, and segregated clusters of communities in terms of income, with the latter class showing the opposite trends. Our findings provide useful lessons in designing urban habitats that serve the larger interests of all inhabitants irrespective of their economic status.

The Role of Sense of Direction and Other Factors During Navigation in a Large-Scale, Unconstrained Environment

2013 ◽  
Author(s):  
Elisabeth J. Ploran ◽  
Ericka Rovira ◽  
James C. Thompson ◽  
Raja Parasuraman
Keyword(s):  
Large Scale ◽  
Sense Of Direction

Magnetic Properties of xCeO2•(50 − x) PbO•50B2O3 Glasses and Glass Ceramics

2017 ◽  
Vol 13 (1) ◽  
pp. 4486-4494 ◽  
Author(s):  
G.El Damrawi ◽  
F. Gharghar
Keyword(s):  
Magnetic Properties ◽  
Large Scale ◽  
Glass Ceramics ◽  
Magnetic Behavior ◽  
Crystal Formation ◽  
Dual Roles ◽  
Effective Agent ◽  
Ordered Structures ◽  
Essential Change

Cerium oxide in borate glasses of composition xCeO2·(50 − x)PbO·50B2O3 plays an important role in changing both microstructure and magnetic behaviors of the system. The structural role of CeO2 as an effective agent for cluster and crystal formation in borate network is clearly evidenced by XRD technique. Both structure and size of well-formed cerium separated clusters have an effective influence on the structural properties. The cluster aggregations are documented to be found in different range ordered structures, intermediate and long range orders are the most structures in which cerium phases are involved. The nano-sized crystallized cerium species in lead borate phase are evidenced to have magnetic behavior.  The criteria of building new specific borate phase enriched with cerium as ferrimagnetism has been found to keep the magnetization in large scale even at extremely high temperature. Treating the glass thermally or exposing it to an effective dose of ionized radiation is evidenced to have an essential change in magnetic properties. Thermal heat treatment for some of investigated materials is observed to play dual roles in the glass matrix. It can not only enhance alignment processes of the magnetic moment but also increases the capacity of the crystallite species in the magnetic phases. On the other hand, reverse processes are remarked under the effect of irradiation. The magnetization was found to be lowered, since several types of the trap centers which are regarded as defective states can be produced by effect of ionized radiation. 

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