Spread of an Influenza Virus

The spread of flu has a strong mathematical basis. Serfling's model ( (Y=average mortality + trend + 52 week cycle + 26 week cycle + Error) or (Y = a + b₁t + b₂cos(p t / 26) + b₃sin(p t / 26) + b₄cos(p t / 26) + b₅cos(p t / 26) + E ) ), for instance, is used to estimate levels of influenza. The Kermack-McKendrick model (Susceptibles --rIS--> Infectives --qI--> Quarantines) can also be used to model the spread of an epidemic. The animation shown here involves a more complicated model showing an outbreak that originates in Dallas, Texas. It was initially intended to see how population density affects the spread, with factors like airports, roads, and hospital overload thrown in. A detailed description of the actual model used and its limitations is available.

This animation was generating using code supplied by Ed Pegg.