Yeah those seem to be fairly harmless at first, but finding a few of them like this...

[He went through, finding a slightly thicker one.]

Here we go. Starts out with the same symptoms... lack of energy, general apathy, loss of expression...

[He kept reading.]

...eventually culminating on a total loss of emotion. Personality and definining characteristics dissapear but daily tasks and routines aren't interrupted. Sound like anyone you know?