Hirudo medicinalis needs it's own post, don't you think?
For hundreds of years, bloodletting was considered a way to "even out" the humors of the body, which included blood, yellow bile, black bile, and phlegm. (I'm going to have to do a whole post on humors and bloodletting. This stuff is too interesting!) The first documented usage of leeches happened in 200 BC by a Greek physician.
Someone who suffered from too much of the "sanguine" or blood humor tended to have flushed skin. This is also why people with infections and fevers, also looking flushed, were bled.
|Get this man some leeches, STAT!|
Leeches have two interesting compounds in their saliva--an anticoagulant called hirudin and an anesthetic. That way, once the leech bites, the host has no idea and the blood keeps flowing nicely, since most animals are equipped to clot off a cut pretty soon after a bite. Mosquitoes have their own way to keep the blood flowing too.
Adult leeches can suck down 15x their body weight and not need to eat again for a year. They are hermaphrodites. I used to work in a lab in college, and one of the neighboring labs studied leeches. They used to feed them by hanging condoms filled with blood into their tanks. Let's say it together, shall we? Eww.
Today, the hirudin compound if now synthesized and used an an anticoagulant to prevent blood clots.
Leeches themselves are used to help promote circulation after reconstructive and microsurgery for two reasons:
- Leeches can decompress tissues engorged from bleeding or poor venous circulation
- They can remove hematomas (collections of blood)
- Once detached, the bite sites continue to bleed, which can promote circulation of the affected tissue.
Do remember any good leech scenes from books you've read? Do you have any plans to use them in your writing?