Diseases or infections are triggered from going hungry or sustaining injuries. Survival chances are partly random and partly based on how healthy the individual is.
When a villager doesn’t have 100% of his health bar, he has a small chance of getting an infection or disease. The health bar decreases during an attack by an enemy or when the individual has nothing to drink, nothing to eat or is freezing.
Infections and diseases are rare, but the effect is devastating, and the villagers’ chances of survival are slim.
Just like in prehistory, it is simply not possible to treat an individual. The best thing to do is to bring the individual who has an infection or disease back to the village as quickly as possible.
He will then be able to drink, eat, warm up and recover his morale. These different elements have a direct link with how healthy the individual is, which will increase his chances of survival.