Updated Site-Specific Biosafety and Biosecurity Mitigation Risk Assessment, Volume II [open pdf - 19MB]
"For each release event from the NBAF [National Bio and Agro-Defense Facility] that causes a Foot-and-Mouth Disease (FMD) infection at a livestock premises, the consequences of that outbreak must be calculated to understand overall risk. The following approach was taken to predict the probability of an outbreak occurring following a release, to determine where the outbreak begins, and to determine the corresponding consequences of the outbreak:  Determine the probability that an outbreak starts in various possible locations given release quantity and transport pathways;  Estimate the extent and duration of the possible FMD outbreaks in Kansas;  Determine the probability that an outbreak would spread from Kansas to other states;  Estimate the extent and duration of possible FMD outbreaks in states other than Kansas; and  Determine overall risk by combining impact and probability of outbreaks occurring across the region for each release amount and transport pathway. Although this analysis is extensive and is substantially based on data collected from the field and the scientific literature, it is fundamentally a modeling-based approach and therefore has limited ability to predict the absolute probability of an outbreak occurring and the corresponding consequences. That being said, given the shortcomings of the modeling approach (as described in section 6.2.2), the data presented include as thorough a treatment of uncertainty in the modeling as possible. Aleatory uncertainty related to the location in which the outbreak starts (which can be a function of the meteorology on the date the accident happens, for example) is displayed along with uncertainty related to how the outbreak unfolds. Outbreak consequences have components of aleatory and epistemic uncertainty. For example, one source of aleatory uncertainty arises from the timing of an animal shipment relative to the infection of animals on a premises. An example of a source of epistemic uncertainty is the probability of infection should a veterinarian visit an infected farm before visiting an uninfected farm. This uncertainty is presented to provide a reasonable range of possible outbreak risks."
U.S. Department of Homeland Security: http://www.dhs.gov/