Simulating Foot-and-Mouth Disease in the United States using the Animal Disease Spread Model

Animal disease outbreaks are a global concern. These outbreaks can cause food scarcity and economic losses, impact animal health, and, if zoonotic, affect human health. For an outbreak of a disease not currently found within a country, these consequences can be greater. Disease modeling is one tool that can be used to better understand disease spread and evaluate different control strategies. USDA–APHIS–VS–CEAH addresses questions related to minimizing the consequences of outbreaks while protecting our nation’s livestock, food supply, and the environment. Using modeling tools, analysts evaluate alternative control strategies, provide recommendations on planning and effective use of resources, develop surveillance strategies, and estimate the economic impacts of disease control options. In this paper, we used the Animal Disease Spread Model (ADSM) to simulate an outbreak of foot-and-mouth disease when introduced from multiple locations on the same day in a seven-state area of the United States. ADSM is a stochastic, spatially explicit compartmental model that simulates herd-to-herd spread of a highly contagious disease. The outbreak scattered in a variety of directions to other herds; however, only a few locations were infected consistently in a high percentage of iterations. Identifying locations at higher risk for disease introduction and/or spread can help decisionmakers target risk-based surveillance and control strategies. Since ADSM is a new model available to the global modeling community, this paper also discusses the modeling process required by analysts to parameterize and use the model and highlights how this simulation method can provide useful information for decision-makers. ABOUT THE AUTHORS Melissa Schoenbaum is a biological scientist with the USDA–APHIS–VS–CEAH Monitoring and Modeling unit. She received her BS in biological sciences from East Texas State University and her MS in computer information technology from Regis University. She serves as the modeling team’s data management specialist. Dawit Assefa is a Program Analyst with the USDA–APHIS–VS–CEAH Monitoring and Modeling unit. He received a BA in economics and an MS in computer information system from Colorado State University, with an emphasis on business intelligence. He performs data visualization, validation, and cleaning functions using a multitude of software. Josiah Seaman is a software developer working in bioinformatics with a specialty in data visualization. He has a BS from Colorado State University in computer science and is working on a PhD in genetics at Kew Royal Botanical Gardens. Josiah designed a genome visualization program called DNASkittle and founded Newline Technical Innovations. He works with others at Newline on science and automation tools. Lindsey Holmstrom is a veterinary epidemiologist with the USDA–APHIS–VS–CEAH Monitoring and Modeling unit. She received her BS in economics from Baylor University, her doctorate of veterinary medicine (DVM) degree from the College of Veterinary Medicine at Texas A&M University, and her PhD in veterinary epidemiology from the University of California, Davis (awarded March 2017). As part of the modeling team, she helps advance and apply epidemiologic models to develop scenarios involving disease spread, alternative control strategies, and associated impacts. Amy Delgado currently serves as the director of the Monitoring and Modeling Unit of USDA–APHIS–VS–CEAH in Fort Collins, CO. Her work focuses on providing scientific support for emergency response planning for transboundary animal diseases. Dr. Delgado received a BS in animal science prior to receiving her DVM and PhD in epidemiology from Texas A&M University.