new fear unlocked

Because there is no conscious force guiding it

Also based on the picture it was in the right pre frontal cortex. Interesting because most people won't have much in terms of neurologic symptoms with a lesion here, outside of some subtle mood and executive dysfunction issues maybe. You won't get like language problems, weakness, numbness, vision loss etc or more obvious symptoms like you would with brain damage other places. Worm found a stealthy spot in the brain to hide in.

Human induced. Habitat destruction drives more species into more human populated regions

animals many people wouldn't get into contact with (be it with animal waste or any other way) happens way more often > chances of diseases formerly only present in certain animals adapting to have human hosts increases