First people become fatigued, then more and more, until finally they just lie around and sleep.
Finally they die from a total loss of stamina. These people laughed at him and claimed that they felt just fine and they knew for sure that they were okay. But Dr. Koch knew for certain that these people were infected and he regretted that they didn't want to take treatment. And just like this, there is a sleeping sickness of the soul wherein the greatest danger lies in the fact that you don't feel it coming on. Therefore you must be alert.