I started to look further into this epidemic that's been sweeping through the area. I know two things so far:
1. It was indeed caused by a servant of the Plague Doctor.
2. Someone else is investigating, and they're a step ahead of me.
I also discovered that a local company had a shipment of unregistered biological agents sent to one of their storage centers nearby. I'm going to check it out tonight, and see if I can put a stop to it.