To conduct the study, Longini and colleagues created a computer model that calculated the spread of smallpox via aerosol dissemination ?the most likely choice of terrorists ?within a community of 50,000. Members of this virtual community interacted the way people normally do: within households, neighborhoods, preschool groups, schools, a community hospital and the community at large. The age distribution and household sizes were based on the U.S. census for 2000.
Predicting the spread of an infectious disease such as smallpox requires much more than simply connecting dots on a map. Instead Longini and colleagues rely on a tool called stochastic modeling to take into account real-world unpredictability, as well as many factors about the disease and the affected population. In constructing these models, Longini and colleagues begin with assumptions about how people interact and how the virus spreads. They also introduce and evaluate the effectiveness of various intervention strategies.
The study represents the first attempt to integrate what science knows about the natural history of smallpox ?how various forms of the disease manifest over time ?with human patterns of behavior to construct the most-comprehensive model of a smallpox epidemic to date.
"If smallpox appeared in Seattle tomorrow, which it could do, I'm absolutely confident that we could contain it if our recommendations for surveillance and containment were put into practice. I rest easier now that we've done this study," Longini said. "The process was kind of like unveiling the enemy to the point where we
Source:Fred Hutchinson Cancer Research Center