Possible Clues:

• Parasite finds shelter on top of church
• Parasite caught in part of foot when getting up
• Some pale echo for a doctor
• Shelter chief doctor of old
• General has chain for hanger-on
• Major moocher
• Scrounger, on reflection, on the back foot getting to grips with cold
• Adorable echidna might host parasite.
• Creature whose saliva acts as a blood thinner
• Parasite used in early medical procedures