Foot and Mouth Disease in California by Brian Axelsen

Brian completed his thesis at NPS in June 2012.   His work creates and analyzes a state-wide simulation of a foot and mouth disease outbreaks in California, with the goal of computing good control strategies.  Bellow is an executive summary of the thesis and the thesis itself.

Executive Summary

Foot and mouth disease (FMD) is a highly contagious viral disease affecting cloven-hoofed domestic and some wild animals. Most adult animals recover from the disease, but it debilitates them; leading to severely decreased meat and milk production. The economic impact on a country with an FMD outbreak can be extensive due to the cost of eradicating the virus, the secondary effects to local economies, and the international trade impact on all animal products that the country exports. For example, the 2001 outbreak of FMD in the United Kingdom led to the destruction of approximately 4 million animals at an estimated economic loss of $5 billion to the food and agriculture sector, and a comparable amount to the tourism industry (U.S. General Accounting Office [GAO], 2002). Even though the United States has been free of this disease since 1929, the Executive Office of the President, Office of Science and Technology Policy has listed FMD as one of four animal diseases that are “high priority threats” in its Research & Development Plan for 2008–2012 (National Science and Technology Council [NSTC], 2007).

We study the spread of FMD in California using a specifically designed herd-based, disease-spread simulation software package and an efficient design of experiment (DOE) to explore a number of “what-if” scenarios of FMD outbreaks in California. The software package, called InterSpread Plus (ISP), has been used extensively to model outbreaks of this disease in modern livestock countries including the United Kingdom, Republic of Korea, and New Zealand.

Our research makes two major contributions to the study and modeling of FMD in California. First, we undertake a significant data development effort to use a state-of-the-art animal disease simulation, ISP, to analyze potential FMD outbreaks in California. This data will allow future researchers to study alternative scenarios and control strategies as they are developed. Second, we develop an efficient DOE, which allows us to explore 26 disease-spread factors and 46 response factors across 8 outbreak scenarios, using hundreds of thousands of simulations, as opposed to a naive strategy that 73would require more than trillions (2 ). In this way, we can perform simulation analysis of the output to identify the relevant disease and control factors for the spread of FMD in California

The two major results for the control of FMD, as indicated by our analysis, are:

  • The most important disease surveillance is done at dairy and dairy-like facilities, or premises. We see that the surveillance parameters of these premises are the dominant control factors in both decreasing the detection time and decreasing the size of the outbreak. This is likely because these types of premises usually have personnel on staff who have daily contact with their animals and because the clinical signs of infection in cattle are generally easier to detect than in other species. These characteristics lead to decreased time until detection, which leads to quicker implementation of controls and smaller outbreaks. Continued research into how to make this type of surveillance as efficient as possible could have a significant impact on the size of an outbreak if it ever occurs in California.
  • The size and responsiveness of depopulation resources play a significant role in decreasing the size of outbreaks. This is surprising, because our models do not use preemptive depopulation. Instead, the model only depopulates detected premises. The analysis confirmed that depopulating infected premises quickly and significantly limited the spread of the disease. This requires the availability of large amounts of resources in a timely manner. The analysis suggests that if the state does not plan on using preemptive depopulation, then depopulation resources should be readily available on very short notice to facilitate the rapid control of an FMD outbreak.

Thesis Presentation

To be added.

Complete Thesis

Axelsen, B. S. (2012).  Simulating the Spread of an Outbreak of Foot and Mouth Disease in California (Masters Thesis).  Naval Postgraduate School.

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