In Civ Clicker, it is possible for your workers to get sick and/or die.
There are three distinct ways a worker can die in the game:
Starvation is likely the most common form of death and is especially prominent in the early game.
If the number of food you have stored is 0, workers will start dying rapidly.
Workers have a chance of catching sickness and dying.
Sickness occurs only if you have unburied Corpses, the number of workers who become sick scales with population. With a small population few people will become sick, with a large one thousands can become sick at once.