Does disease spread to other units in province?

[Edi]

Normally know. There are a few units with the special ability Plague Carrier (denoted by an icon that looks like a bearded face or something) and they have a chance of causing other units in the province to become diseased. These units are very rare, namely only the Apparition and the Eater of the Dead are ones I can remember offhand.

Then there are units that have the Reaper special ability and they kill off population as well as inflicting disease on units in the province. Mabakiel, Harvester of Sorrows, Poison Golem and commanders equipped with the Bane Venom Charm all have this effect. The icon is a picture of scythe.

Under other circumstances disease cannot spread from unit to unit.

Disease spreading sites have a certain chance of inflicting any unit in the province with disease each turn, ranging from 2% to 10%.