I would have loved to have included a section on leeches in my Poop book, or in my upcoming book about insects, but they just didn’t quite fit into either subject. That’s the beauty of blogging! I can talk about my leeches here!

Leeches are bloodsucking annelids that have been used by doctors for over two thousand years. In ancient and medieval times they were used to help balance the body fluids (called humors). Leeches were used to cure everything from headaches to mental disorders. The ancients weren’t far wrong about the worms’ medical benefits. They secrete an anticoagulant called hirudin that stops the blood from clotting; they were approved by the FDA a few years ago for medicinal use.

My sister, who lives in Russia, tells me the use of leeches is very common there.

Leeches live in fresh water. They attach themselves to you with three rows of tiny teeth that create a Y-shaped incision. They suck until they’re full, which can take as long as forty minutes. Supposedly they inject you with an anesthetic, which numbs the area so you don’t feel any pain outside of the initial bite, but that seems to be a myth. From what I’ve read, leeches hurt. And you can’t just yank them off you; their teeth would remain embedded. You have to either wait for them to get full and fall off on their own, or apply heat or alcohol to get them to loosen their hold.

The job of leech collecting back in medieval times can’t have been much fun. Usually it was done by women, who hiked up their skirts and waded bare-legged into ponds, waiting for the leeches to attach themselves.

Even well into the twentieth century, leeches were a standard dental treatment, according to The Excruciating History of Dentistry. They were applied to ease a toothache, after an extraction, and after root canal. To get the leech to the right place, it had to be coaxed into a “leech tube,” which was an open-at-both-ends glass tube. The end was placed over the problem area and the leech was expected to emerge from its tube and attach itself to the afflicted area. But the leech didn’t always cooperate. Sometimes it could take as much as half an hour for the leech to poke its head out and attach itself. Or it might emerge too quickly, in which case there was a real danger of its going down the patient’s throat.