Leeches are still used in medicine—yes, really. Here's why. - National Geographic

A uncommon benignant of crab called synovial sarcoma landed Ellie Lofgreen astatine the University of Utah Hospital this summer. Surgeons removed a tumor—the size of a tiny cantaloupe—wrapped astir her genu associated and besides chopped retired a fewer inches of bony and musculus connected to the knee. They inserted a metallic implant successful her limb and covered it with a ample flap of musculus and tegument transplanted from her precocious thigh. But a fewer hours later, the flap began turning purple, a sign, the doctors knew, that the transplanted insubstantial was dying.

Saving the graft was captious truthful the aesculapian squad projected a attraction that amazed Lofgreen: leeches.

“I was perfectly floored,” says the 31-year-old Idaho resident. “My archetypal absorption was, Okay, thing but that.”

Aside from the yuck factor, the usage of leeches successful modern medicine often surprises patients fixed that these blood-sucking parasites were agelong dismissed arsenic quackery. But their usage successful integrative and reconstructive country has picked up since 2004, erstwhile the U.S. Food and Drug Administration approved leeches arsenic a aesculapian instrumentality to relieve congested veins and reconstruct humor travel successful compromised grafts.

When doctors connect a portion of insubstantial to different portion of the body, they link humor vessels successful the graft to those successful the surrounding insubstantial to support humor supply. Such surgeries are often successful, but successful situations wherever they don’t spell arsenic planned, the archetypal measurement is to instrumentality the diligent backmost to the operating room, reexamine the stiches, and reattach the humor vessels. But, though rare, that hole tin besides fail.

“Veins are truthful fragile,” says Jayant Agarwal, main of integrative country astatine the University of Utah. Despite making the connection, for example, humor travel could inactive beryllium restrained due to the fact that a vein extremity was damaged during an accident. Other times, uncovering a vein successful a severed finger, for instance, whitethorn itself beryllium a challenge. Without that connection, humor tin excavation successful the transplanted tissue, and that’s erstwhile leeches travel into play.

They supply impermanent beingness support, says Jeffrey Janis, a integrative country adept astatine the Ohio State University Wexner Medical Center, until the body’s ain humor vessels turn into this transferred portion of tissue. Without that help, the insubstantial tin die, helium says.

Where aesculapian leeches travel from

Although determination are much than 600 taxon of leeches, including immoderate that don’t suck blood, the European Hirudo medicinalis and Mediterranean Hirudo verbana are astir often utilized successful medicine. They person 3 saw-like jaws, each bearing astir 100 teeth that the animals usage to puncture skin.

For decades, laboratories successful respective countries including United Kingdom, United States, France, Turkey, and Ukraine person been breeding these aesculapian leeches. Carl Peters-Bond astatine Biopharm U.K., a institution that supplies astir fractional of the aesculapian leeches utilized successful hospitals globally, has been doing this for astir 30 years. It takes anyplace betwixt a twelvemonth and 2 years to rise a leech acceptable for aesculapian use, helium says. The process involves feeding them astatine 3 weeks, 8 to 10 weeks, and past astatine 4 to 5 months, aft which they’re starved for up to 2 years. “We lone vessel leeches with an bare gut,” helium says.

As soon arsenic an exigency telephone arrives, Peters-Bond packs betwixt a twelve and 60 leeches successful a gel-filled jar and ships them to a hospital. Sometimes, infirmary pharmacies pre-order and banal aesculapian leeches successful a refrigerator for erstwhile a patient, with a severed finger, oregon successful request of an receptor reattachment oregon bosom reconstruction surgery, whitethorn request them. But these creatures travel with a champion earlier 3 months date, Peters-Bond mentions.

How leech therapy works 

When a leech bites, it dilatory sucks humor and injects compounds similar hirudin and calin—present successful its saliva—that support the humor from clotting. Leech saliva besides contains histamine-like substances that dilate humor vessels and amended humor flow. Physicians person besides utilized anticoagulants similar heparin to forestall humor clots from forming during reconstructive surgeries. But you inactive request the progressive sucking of blood, Agarwal says.

Depending connected the size of the graft and the grade of congestion, leeching tin proceed for 3 to 10 days oregon more, until the insubstantial looks “less swollen, little purple, much normal,” Janis says. Patients stay successful the infirmary portion aesculapian unit supervise the process—replacing each engorged leech with a caller starved one. Each critter tin lone beryllium utilized erstwhile and is drowned successful intoxicant aft it has served its purpose.

Over the people of 2 weeks, Lofgreen had much than 100 leeches drain her dingy-looking tissue. With assistance from nurses and crowdsourced suggestions via Facebook, her household named each 1 of these invertebrates. Some of Lofgreen’s favorites included Aleecha Keys, Clint Leechwood, Sir Leech-a-lot, and Queen Laleecha. Every 4 hours, a caregiver would travel successful and spot a caller leech, which would suck humor anyplace betwixt 15 to 120 minutes earlier falling disconnected and landing connected her bed. While undergoing the therapy, doctors gave her humor transfusions to regenerate the mislaid blood.

But getting the leech to latch connected was a conflict sometimes; ensuring it stays wherever it should was trickier. Initially, nurses utilized a four-ounce integrative cup, which they inverted and taped onto Lofgreen’s tegument to incorporate the leech. But the critter would often sneak out. The unit past created a obstruction utilizing a portion of gauze with a spread wherever they wanted the leech to attach; they hoped the gauze would discourage it from wandering disconnected to surrounding skin. But that wasn’t foolproof either. What worked champion was her mother’s and sister’s watchful eyes. Throughout the time they would instrumentality turns watching for rogue leeches and instantly alert the nurses. Lofgreen felt nary sensation erstwhile these parasites spot into the transplanted tissue, but it pinched sharply erstwhile they spot elsewhere. “It was similar pins and needles,” she says.

Over time, the portion of her insubstantial that initially appeared acheronian and necrotic turned airy purple and the tegument looked much normal. “We had immoderate occurrence with the leeches,” Lofgreen says. But aft she returned home, a tiny conception of the flap got infected and had to beryllium removed. The corruption wasn’t linked to leeching but alternatively the effect of an unfastened wound. However, she credits the slimy slithering creatures with redeeming the bulk of the transplanted flap.

A study that looked astatine 277 cases of aesculapian leech usage reported a 78 percent occurrence rate. “It’s a precise charismatic enactment for flap salvage,” says Ernest Azzopardi, a integrative country specializer astatine University College London successful England and co-author of the study. But a deficiency of robust randomized power trials, the golden modular for evaluating the effectiveness of an intervention, has meant less confidence successful utilizing leech therapy.

Another downside is that patients tin make tegument infections successful effect to specified treatments owed to the Aeromonas bacteria that unrecorded successful leech guts and are recovered successful their saliva. Leech breeders similar Peters-Bond don’t usage antibiotics. Although the drugs could wide these gut bacteria, they travel back, helium says. “What we bash is starve the leeches truthful there’s nary beingness of humor successful the gut and the bacteria is astatine its minimum.” In hospitals, doctors typically prescribe patients antibiotics arsenic a preventative measure, but evidence of immoderate Aeromonas bacteria processing absorption to commonly-used drugs is emerging, making the therapy a challenging 1 to use.

Robotic leeches 

For years, scientists person been searching for alternatives to leeching. Early attempts day backmost to the 19th period erstwhile leeches were successful precocious request successful Europe and the invertebrates were becoming scarce and frankincense much expensive. In 1817, Jean-Baptiste Sarlandière, a French anatomist and physiologist, for instance, developed a instrumentality called the bdellometer, which drained humor from patients.

Agarwal, for instance, has been moving with colleagues astatine the University of Utah since 2013 to make a mechanical leech that tin present an anticoagulant but besides mimic the leeches’ suction. The prototype consists of an array of needles that puncture the skin, wherever a cardinal needle would proviso the anti-coagulate heparin to the humor saturated insubstantial and surrounding needles connected to a pump would suction blood. This thumb pad-sized instrumentality would let doctors to power the measurement and complaint of humor aspirated, which isn’t imaginable erstwhile utilizing existent leeches. For now, the squad is trying to cleanable the travel of anticoagulant into the insubstantial wherever the instrumentality is attached.

Other scientists, too, person developed similar prototypes that clasp promise. Some have tested their show successful animals. But successful presumption of a mechanical replacement that’s acceptable for usage successful humans, “we’re not rather determination yet,” Azzopardi says. For now, these blood-sucking parasites proceed to clasp a niche but important spot successful modern medicine.