Modeling the 2014-2015 vesicular stomatitis outbreak in the United States using an SEIR-SEI approach

Authors: Humphreys Jr, John; PELZEL-MCCLUSKEY, ANGELA - Animal And Plant Health Inspection Service (APHIS); Shults, Phillip; Velazquez Salinas, Lauro; Bertram, Miranda; McGregor, Bethany; Cohnstaedt, Lee; Swanson, Dustin; Peters, Debra; Rodriguez, Luis; Scroggs, Stacey; FAUTT, CHAD - Oak Ridge Institute For Science And Education (ORISE); MOONEY, AMBER - Oak Ridge Institute For Science And Education (ORISE)

Submitted to: Viruses
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/15/2024
Publication Date: 8/18/2024
Citation: Humphreys Jr, J.M., Pelzel-McCluskey, A.M., Shults, P.T., Velazquez Salinas, L., Bertram, M.R., McGregor, B.L., Cohnstaedt, L.W., Swanson, D.A., Peters, D.C., Rodriguez, L.L., Scroggs, S.L., Fautt, C., Mooney, A. 2024. Modeling the 2014-2015 vesicular stomatitis outbreak in the United States using an SEIR-SEI approach. Viruses. 16(8). Article 1315. https://doi.org/10.3390/v16081315.
DOI: https://doi.org/10.3390/v16081315

Interpretive Summary: Vesicular stomatitis (VS) is a disease caused by the vesicular stomatitis New Jersey virus (VSNJV). It affects livestock and is spread by insects. This study uses a new type of model called SEIR-SEI to understand how VSNJV spreads. The model looks at both animals and insects that transmit the virus, and it takes into account the different abilities of these groups to spread the disease, as well as biases in reported cases. The study focused on the 2014-2015 outbreak in the United States. Using mathematical methods, researchers estimated key factors like how often the disease spreads, the effective reproduction number (Rt), and how long it takes for symptoms to appear. The model showed that many infections were not reported, with only 10-24% being documented and only 23% of those cases showing symptoms. These results highlight the need to consider the varying abilities of animals and insects to spread the virus and the fact that not all cases are detected. This approach is important for accurately understanding outbreaks and planning effective control measures. This SEIR-SEI model is a starting point for future improvements to better understand and manage VS. Enhanced monitoring and targeted actions are recommended to handle future VS outbreaks effectively.

Technical Abstract: Vesicular stomatitis (VS) is a vector-borne disease affecting livestock caused by the vesicular stomatitis New Jersey virus (VSNJV). This study presents the first application of an SEIR-SEI compartmental model to analyze VSNJV transmission dynamics. Focusing on the 2014-2015 outbreak in the United States, the model integrates vertebrate hosts and insect vector demographics while accounting for heterogeneous competency within the populations and observation bias in documented disease cases. Key epidemiological parameters were estimated using Bayesian inference and Markov Chain Monte Carlo (MCMC) methods, including the force of infection, effective reproduction number (Rt), and incubation periods. The model revealed significant underreporting, with only 10-24% of infections documented, 23% of which presented with clinical symptoms. These findings underscore the importance of including competence and imperfect detection in disease models to accurately depict outbreak dynamics and inform effective control strategies. As a baseline model, this SEIR-SEI implementation is intended to serve as a foundation for future refinements and expansions to enhance our understanding of VS dynamics. Enhanced surveillance and targeted interventions are recommended to manage future VS outbreaks.