Perhaps the best known advocate of medical leeches is Roy Sawyer, an American researcher. Several decades ago, he recognized the potential benefits of "leech therapy" and started one of the world's first modern leech farms. Today, the company -- Biopharm, based in Britain -- provides tens of thousands of leeches every year to hospitals in dozens of countries. Two species are commonly used in leech therapy, which can last for up to 10 days.
Leeches do have their downsides. Sometimes, they slip off patients and reattach themselves in unwanted places. And no matter how helpful, some patients simply can't stomach the thought of a blood-sucking parasite burrowing into their skin. So some scientists have developed a "mechanical leech" that can perform some of the same duties -- without the gross-out factor.
"In the case of the leech in medicine, we think we can improve on nature," says Nadine Connor, a University of Wisconsin at Madison scientist who in 2001 helped develop the mechanical leech. The device, which looks a little like a small bottle attached to a suction cup, delivers an anti-clotting drug to damaged tissue and then gently sucks out as much blood as needed. And, unlike real leeches, the mechanical version is insatiable and can remove as much blood as doctors think is necessary (real leeches drop off when engorged with blood).
"But perhaps the mechanical device's biggest advantage is that it is not a leech," says Connor. "People don't want this disgusting organism hanging on their body. This added psychological stress for both patient and family members compounds an already difficult situation."
Other physicians, however, still swear by the natural wrigglers. Leeches, they say, are a nearly perfect -- and self-reproducing -- surgical tool. And the leech's bite, they add, isn't nearly as bad as its reputation.