Plague Spread

Plague initially starts in any one of the five Italian fiefs below.

Each season thereafter, there is a 90% chance that any never before plagued fief will get it from an adjacent fief that has had the plague. You know a fief has been plagued because the year of its last infection will be in the fief file PLAGUE field (otherwise, that field contains nothing). Once a fief has been plagued, it undergoes the reoccurrence routine (below) every season.

Note that the above spread routine is not completely realistic, but it is close enough for now. If you want to do it up historically, then make the chance of spread to adjacent fief 80% and give each port in the game a 40% chance of getting it (for the first time) each season. This would be a more complex piece of code and can wait for roll out or later.

The Plague routines can be made fully automatic by using the probabilities in the Plague Reoccurrence table (the START column, plus the Reoccurrence Probability for the probability of plague starting in that fief.) Once plague has infected one fief, this "Plague Start" routine must be turned off.