Hyperbolic models for the spread of epidemics on networks: kinetic description and numerical methods

We consider the development of hyperbolic transport models for the propagation in space of an epidemic phenomenon described by a classical compartmental dynamics. The model is based on a kinetic description at discrete velocities of the spatial movement and interactions of a population of susceptible, infected and recovered individuals. Thanks to this, the unphysical feature of instantaneous diffusive effects, which is typical of parabolic models, is removed. In particular, we formally show how such reaction-diffusion models are recovered in an appropriate diffusive limit. The kinetic transport model is therefore considered within a spatial network, characterizing different places such as villages, cities, countries, etc. The transmission conditions in the nodes are analyzed and defined. Finally, the model is solved numerically on the network through a finite-volume IMEX method able to maintain the consistency with the diffusive limit without restrictions due to the scaling parameters. Several numerical tests for simple epidemic network structures are reported and confirm the ability of the model to correctly describe the spread of an epidemic

Kinetic Modelling of Epidemic Dynamics: Social Contacts, Control with Uncertain Data, and Multiscale Spatial Dynamics

In this survey we report some recent results in the mathematical modelling of epidemic phenomena through the use of kinetic equations. We initially consider models of interaction between agents in which social characteristics play a key role in the spread of an epidemic, such as the age of individuals, the number of social contacts, and their economic wealth. Subsequently, for such models, we discuss the possibility of containing the epidemic through an appropriate optimal control formulation based on the policy maker’s perception of the progress of the epidemic. The role of uncertainty in the data is also discussed and addressed. Finally, the kinetic modelling is extended to spatially dependent settings using multiscale transport models that can characterize the impact of movement dynamics on epidemic advancement on both one-dimensional networks and realistic two-dimensional geographic settings

Epidemic thresholds and human mobility

A comprehensive view of disease epidemics demands a deep understanding of the complex interplay between human behaviour and infectious diseases. Here, we propose a flexible modelling framework that brings conclusions about the influence of human mobility and disease transmission on early epidemic growth, with applicability in outbreak preparedness. We use random matrix theory to compute an epidemic threshold, equivalent to the basic reproduction number [Formula: see text], for a SIR metapopulation model. The model includes both systematic and random features of human mobility. Variations in disease transmission rates, mobility modes (i.e. commuting and migration), and connectivity strengths determine the threshold value and whether or not a disease may potentially establish in the population, as well as the local incidence distribution.The project leading to these results has received funding from “la Caixa” Foundation (ID 100010434), under Agreement HR-18-0036, and the program EU Horizon 2020, Grant Agreement “VEO” No. 874735.S

Assessing a fossil fuels externality with a new neural networks and image optimisation algorithm: the case of atmospheric pollutants as confounders to COVID-19 lethality

This paper demonstrates how the combustion of fossil fuels for transport purpose might cause health implications. Based on an original case study [i.e. the Hubei province in China, the epicentre of the coronavirus disease-2019 (COVID-19) pandemic], we collected data on atmospheric pollutants (PM2.5, PM10 and CO2) and economic growth (GDP), along with daily series on COVID-19 indicators (cases, resuscitations and deaths). Then, we adopted an innovative Machine Learning approach, applying a new image Neural Networks model to investigate the causal relationships among economic, atmospheric and COVID-19 indicators. Empirical findings emphasise that any change in economic activity is found to substantially affect the dynamic levels of PM2.5, PM10 and CO2 which, in turn, generates significant variations in the spread of the COVID-19 epidemic and its associated lethality. As a robustness check, the conduction of an optimisation algorithm further corroborates previous results

No. 3: Linking Migration, HIV/AIDS and Urban Food Security in Southern and Eastern Africa

This publication seeks to establish a background for understanding the complex and dynamic linkages between urbanization, migration, HIV/AIDS and urban food security in Southern and Eastern Africa (SEA). As urbanization accelerates, direct food transfers from rural areas are increasing as poor urban households seek to reduce their vulnerability to high food prices and a cash-intensive urban existence. At the same time, urban households or individual migrants remit money back to households in rural areas both inside and outside the country of employment. A significant proportion of remittances are used for consumption purposes, including the purchase of food. These processes are underwritten by various forms of rural-urban, cross-border and circulatory migration. Migration has clearly facilitated the rapid spread of HIV in the SEA region over the last two decades. For a number of reasons, migrants and other mobile people are especially vulnerable to HIV/AIDS. The epidemic, in turn, is leading to new forms of migration, including children’s migration and return migration of PLWHAs (People Living with HIV and AIDS) to rural areas. Not only does this lead to a decline in remittances but it places a greater burden on rural households. Rural food production for urban household members may also be negatively affected by the impact of HIV/AIDS on rural producers. In the context of HIV/AIDS, migrants themselves may be unable to pursue other food security avenues, including urban agriculture. As HIV/AIDS creates both short term and long term intergenerational impacts within the framework of its long wave epidemiological pattern, the development context is changing considerably. In order to formulate appropriate policy responses, it is therefore imperative to understand the complex linkages and transfers of people and commodities which characterize the “new social economy of migration” in the SEA. At the same time, it is important to understand the inter-related connections between migration and HIV/AIDS for two basic reasons. First, migrants are a particularly vulnerable group, both to HIV infection and to resultant food insecurity. Second, a disease which eats away at the fabric of the new social economy of migration will severely test the ability of urban and rural areas to provide a secure food supply for their populations, both at the aggregate and household levels. It is against this backdrop that this publication documents the key dimensions of the complex connections between urbanization, migration, HIV/AIDS and food security. There is an existing and growing literature on some of these connections; between migration and HIV/AIDS, for example, and between HIV/AIDS and rural food security. However, the linkages between HIV/AIDS and urban food security are less well-established. In addition, attempts to link both HIV/AIDS and urban food security simultaneously with migration are only now being considered, and this project is the first to examine these dynamics at the regional level. That task is rendered more challenging by the fact that migration itself has been undergoing rapid changes in form over the last decade. The publication is divided into three sections. It is designed to lay the foundation for further discussion and the articulation of a targeted action research agenda which addresses both the knowledge gaps and the policy and programming needs of the region in this field of development. This paper begins by reviewing the literature on urbanization and migration in SEA, showing how rapid urbanization is not eliminating migration but intensifying its scope and scale. The section also provides an overview of the HIV/AIDS epidemic in SEA and seeks to establish the reciprocal connections in the HIV/AIDS and migration nexus. Finally, the section reviews current evidence on the determinants of food security in urban areas. The second chapter focuses on the links between migration and HIV/AIDS, migration and food security, and HIV/AIDS and food security. Research on these sets of linkage is proceeding apace although much more is known about the impact of HIV/AIDS on rural than urban food security. The third chapter draws together these sets of relationships and outlines the key knowledge gaps and emerging research questions for the region. Although the research literature is not yet developed in this regard, various conceptual models have been devised to help understand these relationships. Although some of these models focus on rural food security and some on urban, this paper argues that the distinction is artificial, and that migration is the “missing link” between the urban and the rural. Migration links the rural and the urban social economies and emphasizes the point that urban food security cannot be isolated from rural food security and vice-versa. Finally, the paper proposes some next steps in developing a fully fledged and policy-relevant research agenda

A baseline appraisal of water-dependant ecosystem services, the roles they play within desakota livelihood systems and their potential sensitivity to climate change

This report forms part of a larger research programme on 'Reinterpreting the Urban-Rural Continuum', which conceptualises and investigates current knowledge and research gaps concerning 'the role that ecosystems services play in the livelihoods of the poor in regions undergoing rapid change'. The report aims to conduct a baseline appraisal of water-dependant ecosystem services, the roles they play within desakota livelihood systems and their potential sensitivity to climate change. The appraisal is conducted at three spatial scales: global, regional (four consortia areas), and meso scale (case studies within the four regions). At all three scales of analysis water resources form the interweaving theme because water provides a vital provisioning service for people, supports all other ecosystem processes and because water resources are forecast to be severely affected under climate change scenarios. This report, combined with an Endnote library of over 1100 scientific papers, provides an annotated bibliography of water-dependant ecosystem services, the roles they play within desakota livelihood systems and their potential sensitivity to climate change. After an introductory, section, Section 2 of the report defines water-related ecosystem services and how these are affected by human activities. Current knowledge and research gaps are then explored in relation to global scale climate and related hydrological changes (e.g. floods, droughts, flow regimes) (section 3). The report then discusses the impacts of climate changes on the ESPA regions, emphasising potential responses of biomes to the combined effects of climate change and human activities (particularly land use and management), and how these effects coupled with water store and flow regime manipulation by humans may affect the functioning of catchments and their ecosystem services (section 4). Finally, at the meso-scale, case studies are presented from within the ESPA regions to illustrate the close coupling of human activities and catchment performance in the context of environmental change (section 5). At the end of each section, research needs are identified and justified. These research needs are then amalgamated in section 6

Agent-based modelling of cholera diffusion

This paper introduces a spatially explicit agent-based simulation model for micro-scale cholera diffusion. The model simulates both an environmental reservoir of naturally occurring V. cholerae bacteria and hyperinfectious V. cholerae. Objective of the research is to test if runoff from open refuse dumpsites plays a role in cholera diffusion. A number of experiments were conducted with the model for a case study in Kumasi, Ghana, based on an epidemic in 2005. Experiments confirm the importance of the hyperinfectious transmission route, however, they also reveal the importance of a representative spatial distribution of the income classes. Although the contribution of runoff from dumpsites can never be conclusively proven, the experiments show that modelling the epidemic via this mechanism is possible and improves the model results. Relevance of this research is that it shows the possibilities of agent-based modelling combined with pattern reproduction for cholera diffusion studies. The proposed model is simple in its setup but can be extended by adding additional elements such as human movement and change of behaviour of individuals based on disease awareness. Eventually, agent-based models will open opportunities to explore policy related research questions related to interventions to influence the diffusion process