title: Individual-Based Modeling of Tuberculosis in a User-Friendly Interface: Understanding the Epidemiological Role of Population Heterogeneity in a City.
abstract: For millennia tuberculosis (TB) has shown a successful strategy to survive, making it one of the world's deadliest infectious diseases. This resilient behavior is based not only on remaining hidden in most of the infected population, but also by showing slow evolution in most sick people. The course of the disease within a population is highly related to its heterogeneity. Thus, classic epidemiological approaches with a top-down perspective have not succeeded in understanding its dynamics. In the past decade a few individual-based models were built, but most of them preserved a top-down view that makes it difficult to study a heterogeneous population. We propose an individual-based model developed with a bottom-up approach to studying the dynamics of pulmonary TB in a certain population, considered constant. Individuals may belong to the following classes: healthy, infected, sick, under treatment, and treated with a probability of relapse. Several variables and parameters account for their age, origin (native or immigrant), immunodeficiency, diabetes, and other risk factors (smoking and alcoholism). The time within each infection state is controlled, and sick individuals may show a cavitated disease or not that conditions infectiousness. It was implemented in NetLogo because it allows non-modelers to perform virtual experiments with a user-friendly interface. The simulation was conducted with data from Ciutat Vella, a district of Barcelona with an incidence of 67 TB cases per 100,000 inhabitants in 2013. Several virtual experiments were performed to relate the disease dynamics with the structure of the infected subpopulation (e.g., the distribution of infected times). Moreover, the short-term effect of health control policies on modifying that structure was studied. Results show that the characteristics of the population are crucial for the local epidemiology of TB. The developed user-friendly tool is ready to test control strategies of disease in any city in the short-term.
authors.affiliation: Departament de Física, Escola Superior d'Agricultura de Barcelona, Universitat Politècnica de Catalunya-BarcelonaTech Barcelona, Spain.
authors.forename: Clara
authors.initials: C
authors.lastname: Prats
authors.affiliation: Departament d'Estadística i Investigació Operativa, Facultat d'Informàtica de Barcelona, Universitat Politècnica de Catalunya-BarcelonaTech, Barcelona Supercomputing Centre (BSC-CNS) Barcelona, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Montañola-Sales
authors.affiliation: Departament d'Estadística i Investigació Operativa, Facultat d'Informàtica de Barcelona, Universitat Politècnica de Catalunya-BarcelonaTech, Barcelona Supercomputing Centre (BSC-CNS) Barcelona, Spain.
authors.forename: Joan F
authors.initials: JF
authors.lastname: Gilabert-Navarro
authors.affiliation: Departament de Física, Escola Superior d'Agricultura de Barcelona, Universitat Politècnica de Catalunya-BarcelonaTech Barcelona, Spain.
authors.forename: Joaquim
authors.initials: J
authors.lastname: Valls
authors.affiliation: Departament d'Estadística i Investigació Operativa, Facultat d'Informàtica de Barcelona, Universitat Politècnica de Catalunya-BarcelonaTech, Barcelona Supercomputing Centre (BSC-CNS) Barcelona, Spain.
authors.forename: Josep
authors.initials: J
authors.lastname: Casanovas-Garcia
authors.affiliation: Unitat de Tuberculosi Experimental, Fundació Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol, Universitat Autònoma de Barcelona Badalona, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Vilaplana
authors.affiliation: Unitat de Tuberculosi Experimental, Fundació Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol, Universitat Autònoma de Barcelona Badalona, Spain.
authors.forename: Pere-Joan
authors.initials: PJ
authors.lastname: Cardona
authors.affiliation: Departament de Física, Escola Superior d'Agricultura de Barcelona, Universitat Politècnica de Catalunya-BarcelonaTech Barcelona, Spain.
authors.forename: Daniel
authors.initials: D
authors.lastname: López
keywords: HIV-tuberculosis; contact tracing; diagnosis delay; epidemiology; immigrant; individual-based model; risk factors; tuberculosis