Talk to Wimmip in Tarsengaard magic school's Animal Study room [270,190]
She will send you to find creatures that are diseased, as a hint she says that the creatures will be in places where there are other creatures like them.
You will need to kill (in no particular order):
Rat (found in the Rat Cave in Isla Prima, near the entrance)
Male Goblin (found in Naralik, near the center of the map)
Puma (found in White Stone, Elavro Mountains)
Ogre (found in Palon Vertas, in the front of the blacksmith cave)
Cyclops (found in Egratia Point, near the temple in the grassy area of the map)
When you kill the creature relevant to the quest, you will get a message
After killing the last creature you get another, additional message, return to Wimmip to collect the reward.