Plague is used in Empire to symbolize all forms of disease and is the only health hazard associated with the Empire game, (ignoring it's effects on the players). The characteristics of plague are, therefore, a compromise of disease features (or "bugs").
Note that if the NO_PLAGUE option is in use, a kindly deity has wiped out the plague for you. If not, worry about it.
All of the timelines below are based on a game with 32 ETU updates.
The Empire Plague takes between 96 and 189 time units to run its course on land, (i.e., 2 to 4 days in any particular sector/ship/land unit if an Empire time unit is 1/2 and hour.) In so doing the plague goes through three stages:
Stage I Edit
The gestation or incubation phase in which no symptoms appear. Sectors, ships and land units that are in this stage of the plague are indistinguishable from healthy ones. This stage lasts 32 to 63 time units, (less than a day and a half).
Stage II Edit
The infectious phase in which the symptoms first appear -- orange blotches on the face and hands, sometimes accompanied by grey stripes on the genitalia, itching of the liver and spleen, an uncontrollable fear of ripe tomatoes, etc. During this phase the plague is extremely communicable; for example, a simple delivery from an infectious sector will infect the destination sector.
Stage III Edit
The terminal phase in which people die, often in the act of fleeing from (real or imagined) tomatoes. The number of people that die is roughly inversely proportional to the research level of the country (plus 100).
All three phases are of roughly equal average duration, (about 48 time periods or 1 day).
Plague usually arises in countries with high technological development and comparatively little medical research. It arises specifically in sectors with high population density and low efficiency.
Recently archaeologists have uncovered a treatise by a Dr. M. Welby entitled "Demographic considerations and the Empire Plague". In part it states:
It appeared that our original hypothesis based on the high percentage of Lumbagan Legionnaires among the afflicted had led us down a blind alley and that if we were to solve this complex puzzle before the end of the series in the spring [possibly a reference to the series of tests leading to the mysterious "Neilson Rating"] we would have to turn to other disciplines for help. It was only by the merest lucky coincidence that as I drove home one evening ... [here Dr. Welby relates an amusing anecdote about a Brownie Scout and the director of a film entitled "Close Encounters of the Third Grade"] ... leading us to the following amazing formulation of the relationship between medical research, technology, population, standard of living and the Empire Plague:The likelihood of plague outbreak (in percent) is
civ + mil + uw t_level + (iron + oil + rad * 2) / 10 + 100
max (0, -------------- * ------------------------------------------- - 1)
max_pop r_level + effic + mobil + 100
Many researchers have commented on the surprising lack of correlation between food supply and plague outbreak.
Fortunately, the plague is only infectious while a sector, ship or land unit is actively battling the plague (Stage II). The most effective method for curing plague has been to isolate the sick as soon as an outbreak has been spotted.
This includes preventing any loading and unloading of ships and land units (since they can, of course, carry plague), explorations out of the sector, moving commodities out of the sector, even by air, distribution or delivery, etc. Basically, any people or commodities that originate from a sector, ship or land unit actively battling plague will cause the destination sector, ship or land unit to become infected. Beware, "people" includes pilots.
Once an outbreak has been spotted, the plague takes on an infectious state at the next update. There is very little time to isolate the sector and limitdeaths caused by plague.