I'm not sure about you, but leeches have always occupied a major role in my subconscious. I'll attribute that to an early brush with a colony of the hermaphroditic dears, a somber first viewing of Stand By Me, and a cathartic summer spent impaling buckets full of them onto fish hooks (walleyes freaking love them). The kinds of leeches that suck blood can handle a load up to five times their size, a meal that can last them the next six months. If you've ever had a leech sidle up to you, you probably won't be surprised to learn about their three sets of jaws and the "chitinous saw" that goes to work on your epidermal layer. But like some kind of afterthought, they secrete anesthetizing agents and blood thinners into the leeching zone--a combo that makes them popular in the medical world. Leeches are still used today, especially in skin grafts. Patient response has been described as "amazingly stoic." And while we're discussing burrowing/sucking "healers", might as well consider the maggot.
This man employed the squirming masses to help a patient's bedsores:
Dugas put the eggs on the patient's bedsores, just as doctors had done with his grandmother's infections. The eggs hatched as maggots, fed on the infected tissue, turned into flies, and flew away. Dugas applied more eggs. Within four weeks the patient's sores were clean and filled with healthy tissue. Far from preparing to amputate, Dugas sent the man to a local hospital to receive skin grafts.
Yeah, I'll take the leeches.