981 research outputs found
Analysis of a model for waterborne diseases with Allee effect on bacteria
A limitation of current modeling studies in waterborne diseases (one of the leading causes of death worldwide) is that the intrinsic dynamics of the pathogens is poorly addressed, leading to incomplete, and often, inadequate understanding of the pathogen evolution and its impact on disease transmission and spread. To overcome these limitations, in this paper, we consider an ODEs model with bacterial growth inducing Allee effect. We adopt an adequate functional response to significantly express the shape of indirect transmission. The existence and stability of biologically meaningful equilibria is investigated through a detailed discussion of both backward and Hopf bifurcations. The sensitivity analysis of the basic reproduction number is performed. Numerical simulations confirming the obtained results in two different scenarios are shown
Modeling and Controlling the Spread of Epidemic with Various Social and Economic Scenarios
We propose a dynamical model for describing the spread of epidemics. This
model is an extension of the SIQR (susceptible-infected-quarantined-recovered)
and SIRP (susceptible-infected-recovered-pathogen) models used earlier to
describe various scenarios of epidemic spreading. As compared to the basic SIR
model, our model takes into account two possible routes of contagion
transmission: direct from the infected compartment to the susceptible
compartment and indirect via some intermediate medium or fomites. Transmission
rates are estimated in terms of average distances between the individuals in
selected social environments and characteristic time spans for which the
individuals stay in each of these environments. We also introduce a collective
economic resource associated with the average amount of money or income per
individual to describe the socioeconomic interplay between the spreading
process and the resource available to infected individuals. The
epidemic-resource coupling is supposed to be of activation type, with the
recovery rate governed by the Arrhenius-like law. Our model brings an advantage
of building various control strategies to mitigate the effect of epidemic and
can be applied, in particular, to modeling the spread of COVID-19.Comment: 14 pages, 6 figures, 5 table
Traveling waves for a diffusive SIR-B epidemic model with multiple transmission pathways
In this work, we consider a diffusive SIR-B epidemic model with multiple transmission pathways and saturating incidence rates. We first present the explicit formula of the basic reproduction number R0. Then we show that if R0 > 1, there exists a constant c ∗ > 0 such that the system admits traveling wave solutions connecting the disease-free equilibrium and endemic equilibrium with speed c if and only if c ≥ c Since the system does not admit the comparison principle, we appeal to the standard Schauder’s fixed point theorem to prove the existence of traveling waves. Moreover, a suitable Lyapunov function is constructed to prove the upward convergence of traveling waves
Detection of Pathogens in Water Using Micro and Nano-Technology
Detection of Pathogens in Water Using Micro and Nano-Technology aims to promote the uptake of innovative micro and nano-technological approaches towards the development of an integrated, cost-effective nano-biological sensor useful for security and environmental assays.Â
The book describes the concerted efforts of a large European research project and the achievements of additional leading research groups. The reported knowledge and expertise should support in the innovation and integration of often separated unitary processes. Sampling, cell lysis and DNA/RNA extraction, DNA hybridisation detection micro- and nanosensors, microfluidics, together also with computational modelling and risk assessment can be integrated in the framework of the current and evolving European regulations and needs. The development and uptake of molecular methods is revolutionizing the field of waterborne pathogens detection, commonly performed with time-consuming cultural methods. The molecular detection methods are enabling the development of integrated instruments based on biosensor that will ultimately automate the full pathway of the microbiological analysis of water
Detection of Pathogens in Water Using Micro and Nano-Technology
Detection of Pathogens in Water Using Micro and Nano-Technology aims to promote the uptake of innovative micro and nano-technological approaches towards the development of an integrated, cost-effective nano-biological sensor useful for security and environmental assays.Â
The book describes the concerted efforts of a large European research project and the achievements of additional leading research groups. The reported knowledge and expertise should support in the innovation and integration of often separated unitary processes. Sampling, cell lysis and DNA/RNA extraction, DNA hybridisation detection micro- and nanosensors, microfluidics, together also with computational modelling and risk assessment can be integrated in the framework of the current and evolving European regulations and needs. The development and uptake of molecular methods is revolutionizing the field of waterborne pathogens detection, commonly performed with time-consuming cultural methods. The molecular detection methods are enabling the development of integrated instruments based on biosensor that will ultimately automate the full pathway of the microbiological analysis of water
Traveling waves for a diffusive SIR-B epidemic model with multiple transmission pathways
In this work, we consider a diffusive SIR-B epidemic model with multiple transmission pathways and saturating incidence rates. We first present the explicit formula of the basic reproduction number R0. Then we show that if R0 > 1, there exists a constant c ∗ > 0 such that the system admits traveling wave solutions connecting the disease-free equilibrium and endemic equilibrium with speed c if and only if c ≥ c Since the system does not admit the comparison principle, we appeal to the standard Schauder’s fixed point theorem to prove the existence of traveling waves. Moreover, a suitable Lyapunov function is constructed to prove the upward convergence of traveling waves
Global dynamics of a class of age-infection structured cholera model with immigration
This paper is concerned with a class of age-structured cholera model with general infection rates. We first explore the existence and uniqueness, dissipativeness and persistence of the solutions, and the existence of the global attractor by verifying the asymptotical smoothness of the orbits. We then give mathematical analysis on the existence and local stability of the positive equilibrium. Based on the preparation, we further investigate the global behavior of the cholera infection model. Corresponding numerical simulations have been presented. Our results improve and generalize some known results on cholera models
Rotavirus Transmission in Rural, Coastal Ecuador
Rotavirus is a major cause of under-five mortality, particularly in the developing world, yet how it is transmitted is not well understood. How and why rotavirus spreads through populations is a critical concern for both preventing disease and reducing the burden. In this dissertation, I consider how rotavirus spreads through a region by focusing on two important processes: human travel and hydrological transport. I also examine how the introduction of the rotavirus vaccine in a remote region of Ecuador has changed rotavirus transmission, affecting both direct and indirect pathways. I use a combination of regression analysis and simulation modeling to address these questions. In chapter 2, I consider the effect of human travel on rotavirus transmission. To do so, I use longitudinal data from 15 villages in rural, coastal Ecuador to identify important determinants of travel patterns and the extent to which these variables are stable over time. I then incorporate these predictors into a regional transmission model to assess how demographic heterogeneity in travel impacts regional risk of rotavirus and the implications of this heterogeneity for disease interventions. In chapter 3, I investigate the conditions in which rotavirus can be transmitted through water sources and how this pathway depends on both temperature and local hydrologic conditions. I use previously published empirical studies of temperature and rotavirus persistence in water sources to conduct a meta-analysis relating temperature to rotavirus decay in water sources. Then, I combine the resulting temperature-decay function with data on hydrological characteristics of our Ecuador study site to build a transmission model that accounts for both direct transmission and water-mediated transmission. Using this model, I assess the importance of waterborne transmission to amplification of rotavirus infection within communities and spread of rotavirus through hydrological transport within a watershed. In chapter 4, I consider how the Rotarix vaccine has changed rotavirus transmission patterns in our study region. I combine data on rotavirus vaccination from local health posts with 10 years of data from a population based case control study and 18 months of diarrheal disease surveillance to estimate: (1) the direct effect of vaccination on the rate all-cause diarrhea, (2) the overall effect of vaccination on rotavirus infection and all-cause diarrhea both by age group and at a population level, and (3) the fraction of cases attributable to rotavirus in our study region.PHDEpidemiological ScienceUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/144196/1/amullis_1.pd
Vaccine preventable viral diseases and risks associated with waterborne transmission.
Rotavirus and poliovirus are paradigmatic viruses for causing major diseases affecting the human population. The impact of poliovirus is remarkably diminished because of vaccination during the last half century. Poliomyelitis due to wild polio currently affects a limited number of countries, and since 2000 sporadic outbreaks have been associated to neurovirulent vaccine-derived polioviruses. Conversely, rotavirus is presently very diffuse, accounting for the largest fraction of severe gastroenteritis among children <5 years-old. Vaccination towards rotavirus is still in its dawn, and zoonotic strains contribute to the emergence and evolution of novel strains pathogenic to man. The environment, particularly surface water, is a possible vehicle for large transmission of both viruses, but environmental surveillance of circulating strains can help promptly monitor entry of new virulent strains into a country, their shedding and spread
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