Epidemilogical Simulation System, Version 2.4

Software · Fri Jan 30 00:00:00 EST 2004

OSTI ID:1230713

EpiSims uses a detailed simulation of disease spread to evaluate demographically and geographically targeted biological threat reduction strategies. Abstract: EpiSims simulates the spread of disease and analyzes the consequences of intervention strategies in a large urban area at the level of individuals. The simulation combines models of three dynamical systems: urban social networks, disease transmission, and within-host progression of a disease. Validated population mobility and activity generation technology provides the social network models, Disease models are based on fusion of expert opinion and available data. EpiSims provides a previously unavailable detailed representation of the course of an outbreak in urban area. A letter of August 16, 2002 from the Office of Homeland Security states: "Ability of EpiSims to provide comprehensive data on daily activity patterns of individuals makes it far superior to traditional SIR models — clearly had an impact on pre-attack smallpox vaccination policy." EpiSims leverages a unique Los Alamos National Laboratory resource — the population mobility and activity data developed by TRANSIMS (Transportation Analysis and SiMulation System) — to create epidemiological analyses at an unprecedented level of detail. We create models of microscopic (individual-level) physical and biological processes from which, through simulation, emerge the macroscopic (urban regional level) quantities that are the inputs to alternative models. For example, the contact patterns of individuals in different demographic groups determine the overall mixing rates those groups. The characteristics of a person-to-person transmission together with their contact patterns determine the reproductive numbers — how many people will be infected on average by each case. Mixing rates and reproductive numbers are the basic parameters of other epidemiological models. Because interventions — and people’s reactions to them — are ultimately applied at the individual level, EpiSims is uniquely suited to evaluate their macroscopic consequences. For example, the debate over the logistics of targeted vaccination for smallpox, and thus the magnitude of the threat it poses, can best be resolved through an individual- based approach. EpiSims is the only available analytical tool using the individual-based approach that can scale to populations of a million or more without introducing ad-hoc assumptions about the nature of the social network. Impact: The first study commissioned for the EpiSims project was to analyze the effectiveness of targeted vaccination and isolation strategies in the aftermath of a covert release of smallpox at a crowded urban location. In particular we compared casualties and resources required for targeted strategies with those in the case of large-scale quarantine and/or mass vaccination campaigns. We produced this analysis in a sixty-day effort, while prototype software was still under development and delivered it to the Office of Homeland Security in June 2002. More recently, EpiSims provided casualty estimates and cost/benefit analyses for various proposed responses to an attack with pneumonic plague during the TOPOFF-2 exercise. Capabilities: EpiSims is designed to simulate human-human transmissible disease, but it is part of a suite of tools that naturally allow it to estimate individual exposures to air-borne or water-borne spread. Combined with data on animal density and mobility, EpiSims could simulate diseases spread by non-human vectors. EpiSims incorporates reactions of individuals, and is particularly powerful if those reactions are correlated with demographics. It provides a standard for modeling scenarios that cuts across agencies.

• Short Name / Acronym: EpiSims V2.4; 001713MLTPL00
• Site Accession Number: C-04, 018; LA-CC-04-016
• Version: 00
• Programming Language(s): Medium: X; OS: Linux/UNIX w/GCC, MPICH; Compatibility: Multiplatform
• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: DOE/DHS
• Contributing Organization: Stephen G. Eubank, Douglas J. Roberts, Stephen Sydoriak, Karla Atkins, Graham A. Mark, Keith Sisset, Paula Stretz, Kathryn Berkbigler, Brian W. Bush, Deborah A. Kubicek
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 1230713
• Country of Origin: United States