Related Clues:

• Some pale echo for a doctor
• General has chain for hanger-on
• 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
• Parasite left on tree, destroying billions
• Parisitic person
• Sucker about to get taken in by flipping scoundrel
• Worm hot, cold fish sent back
• Aquatic parasite