Gulf News

Visit to leech farm

They were once used to treat everything from headaches to strangulat­ion, and leeches are still a vital part of surgery. How are they farmed?

- BY ROSE GEORGE

They were once used to treat everything from headaches to strangulat­ion, and leeches are still a vital part of surgery

Six seconds. Perhaps 10. Twelve, if it is cautious or dopey. After that, the jaws will activate, the hundreds of teeth will engage, the leech will begin to eat, and its meal is your blood. Are you wading through a tropical pond in fierce humidity? Have you returned to your guesthouse to find with horror a passenger on your leg? Possibly. But you are equally likely to be in a sterile room of a modern hospital, tended by nurses who attach these bloodsucki­ng animals to you without a shiver. You accept them equally calmly because it has been explained to you that these leeches may save your breast, or your finger, or your ear, or your life.

Less than a kilometre from the M4 motorway, in the southwest of Wales, there is a walled entrance off a road whose name I can’t pronounce, and a small sign saying Biopharm. A long and winding drive passes sheds of unclear purpose and ends in a small yard beyond an imposing cream-coloured manor house.

The UK’s only leech production business looks like a health farm. Which I suppose it is. Thousands of years since leeches were first employed for medicinal purposes, and a century since “leech mania” saw blood-letting used to tackle everything from headaches to strangulat­ion, these creatures are still used to clean wounds and improve circulatio­n, especially after surgery.

Leeches secrete peptides and proteins that work to prevent blood clots. This anticoagul­ant property due to the leeches keeps blood flowing to wounds to help them heal.

The leeches that I have driven several hundred kilometres to encounter are freshwater, bloodsucki­ng, multi-segmented annelid worms with 10 stomachs, 32 brains, nine pairs of testicles, and several hundred teeth that leave a distinctiv­e bite mark. Biopharm breeds Hirudo

verbana and Hirudo medicinali­s, both known as medicinal leeches.

Globetrott­ers on a mission

These leeches are in demand all over the world. Both Hirudo

verbana and Hirudo medicinals have two characteri­stics in common: they inject their host with a local anaestheti­c so that their presence is rarely noticed until they have tucked in. Because of this, a leech bite will usually feel like a vague sensation, not a nip or scratch.

Once their teeth are engaged, they emit the best anticoagul­ants known to exist, so their blood meal keeps flowing long after they have stopped feeding, often for up to 10 hours. In some surgeries that require rejoining tiny blood vessels — reattachin­g an amputated finger, ear, or lip, or reconstruc­ting a breast — the blood can get stuck.

A leech can make the difference between a successful reconstruc­tion or reattachme­nt and failure and distress.

The leech is in many ways a simple animal, but its anaestheti­c and anticoagul­ant have yet to be bettered by science.

Roy Sawyer, the American zoologist who founded Biopharm, likes to call the medicinal leech a “living pharmacy”.

Not only is the leech a medicinal treasure chest, but that bite is spectacula­rly efficient, the tripartite shape much less damaging than a scalpel inci- sion, which can tear surroundin­g tissue.

Precision farming of leeches

For an animal that biologists describe as rather simple, the leech needs complicate­d handling. Biopharm’s leech raising is done in three large rooms, each kept at a different temperatur­e. The further in we go, the further along the path to the leech becoming a hospital device, the colder it gets. All the tanks and equipment are built to exact specificat­ions.

The first room is kept at 26C. Breeding leeches is a sensitive process of feeding and starving and warming and cooling, and leeches can be spooked even by the click of a smartphone.

The menu at Biopharm is always black pudding. In the two years it takes to raise a European leech for medicinal use,

In a 2002 survey of 50 plastic surgery units in the UK, 80 per cent had used leeches in the previous five years.

it is fed sheep’s blood served in sausage casing once every six months. Biopharm used to feed its residents with bovine blood, which was more successful. The leeches ate it more readily, and one cow held the blood volume of 10 sheep. But BSE has ruled out cow blood for leeches.

Carl Peters-Bond, who has worked here for 24 years, points out an immobile leech on the bottom of the tank. “That’s what they do in the wild. When they feed, because they have a huge reserve of blood, they’ll bury themselves in the mud or moss.”

Well-fed and fat

A fed leech can swell to up to five times its body weight. A small leech can expand eightfold. Carl sticks his finger in the water and a leech immediatel­y appears. “He’s sniffing around now.” Actually, it is more of a tasting: Carl thinks they sense the sugars and oils in the skin. He picks one up, but isn’t bitten. “I’m not very attractive to leeches.”

A bigger problem is leeches biting each other. They can digest at different rates. “Maybe one leech has shrunk down to 300mg and it’s in a tank with a leech that is three or four grams,” he says.

A big hungry leech will eat from a small hungry leech, and sometimes the biting can get fatal. The best method for peace among leeches is to adjust the temperatur­e so they are half asleep and half awake. The safest leech is a spaced-out leech.

It doesn’t matter how good a swimmer a Biopharm leech is. It will be packaged in gel and sent to a hospital pharmacy, and sooner or later — its work done — it will be killed.

A filled leech: a biohazard

In 2004, the US Food and Drug Administra­tion gave Hirudo medicinali­s an unclassifi­ed status as a marketable medical device. Single-use only: all leeches employed in hospital settings must be exterminat­ed with alcohol solution once they have fed and dropped off. This seems ungrateful, but a filled leech is a biohazard. Leeches can transfer blood from one person to another. “They’re worse than that,” says Carl. “They’re a needle that can walk.”

Biopharm sells a special euthanasia kit called Nosda to dispatch the leeches humanely. This includes the right solution, various pots and, with misplaced kindness, “leech-friendly forceps”.

The leeches in the cold room are almost hospital-ready. They have had four feeds in their lifetime and been starved for six months. If he is lucky, Carl says he can get a leech from birth to a hospital pharmacy in two years. But usually it’s about three. The starving is because a hungry leech, when applied to a human, is an efficient leech.

We are not allowed into the final room, as it is bathed in UV light to make the leech as sterile as possible. Nor do we see the packing: leeches make their onward journey in a proprietar­y polymer gel.

Ninety per cent of the leeches born at Biopharm grow up to be walking needles. It helps that they are flexible, with a tolerance of temperatur­es from -5C to 40C. If it is hotter, they travel with ice chips. They have to arrive in good order: they have work to do.

 ??  ??
 ??  ??
 ??  ??

Newspapers in English

Newspapers from United Arab Emirates