Brood responds differently depending on the Mists. Sometimes triage doctors can recognize the signs of infestation in the field, other times the victim must be brought to a permanent Celestial Circle and be identified. In either case, it's never certain when a broodling will erupt from their host or even if they will. As Eldandiril said, it is also uncertain whether the pain of a hatching broodling cracks a person's spirit instantaneously or merely kills them allowing time for a Life spell. In any case, it is important to realize who might be carrying such a parasite and, at the very least, have them under surveilance. Who else might be infected?
If Brood are infesting Wayside we will need to prepare. Poison Shields will be useful against their paralytic venom, as will Purify potions and Dispel scrolls. We'd be best served stockpiling these items. I have a few Purify potions, but none of the rest. Is there a Potion or Scroll maker who has any of these in stock?
Dramthin Hartsboon
Simple Keeper of the Tainted Grove