Bald’s Leechbook is an English medical book from the ninth century. It was written at the height of the Dark Ages. This was a period of history when much knowledge was based in superstition instead of on facts and reason. The Leechbook gives readers a view into the medicine of the Dark Ages. For example, it suggests that mental illness and certain diseases are the work of mythical creatures called elves. In the treatment of certain eye maladies, it suggests that a physician catch a live crab, remove its eyes, and then place the crab’s eyes on the patient’s neck. Another section provides a recipe for an eye medicine which sounds like it could have come from a fairy tale.
“Take cropleek and garlic, of both equal quantities, pound them well together, take wine and bullocks gall, of both equal quantities, mix with the leek, put this then into a brazen vessel,” the Leechbook instructs. “Let it stand nine days in the brass vessel, wring out through a cloth and clear it well, put it into a horn, and about night time apply it with a feather to the eye.”
Today’s doctors know that blaming diseases on mythical creatures, or using animals to treat the sick, is not good medicine. Research shows that medicines developed and tested by chemists in laboratories are much more effective in treating sick patients. However, one group of researchers learned something unexpected about the strange eye medicine recipe mentioned above.
Currently, researchers in a group called AncientBiotics are reading the Leechbook. They think that this guide for medieval doctors may give modern doctors new ideas about how to treat diseases. They are especially concerned about diseases that do not seem to respond to modern medicines. They hope doctors in the past found ways to save the lives of patients today.
Sometimes when we get sick, a doctor may prescribe a type of medicine called an antibiotic. Antibiotics, such as the well-known medicine penicillin, are effective against illnesses caused by bacterial infections. However, if antibiotics are not used correctly, instead of being eliminated, some bacteria can instead develop a resistance to these drugs. The result is illnesses for which there is no treatment. Currently, about 700,000 people around the world die from illnesses that resist drugs like antibiotics. By the year 2050, scientists think that number could rise to as high as 10 million.
The researchers on the AncientBiotics team hope that the answer to this crisis will be found by studying medical history. The group, which includes both scientists and historians, is creating a database of medieval medical treatments. They want to discover ways that early doctors treated bacterial infections.
“We believe that answers to the antibiotic crisis could be found in medical history,” writes medieval historian Erin Connelly. He is from the University of Pennsylvania and a member of AncientBiotics. “With the aid of modern technologies, we hope to unravel how premodern physicians treated infection and whether their cures really worked.”
In support of the project, Connelly points to the work of Chinese chemist Tu Youyou. Tu received a Nobel Prize in Physiology and Medicine in 2015, making her the first female citizen of the People’s Republic of China to win a Nobel Prize in any category. In trying to find new ways to treat the disease malaria, Tu looked at the past. She studied hundreds of recipes for medicines in ancient Chinese literature. She used what she learned to develop a new treatment. AncientBiotics researchers hope that ancient English medical texts also contain long-forgotten recipes for medicines that will be effective against diseases today.
Currently, the researchers have collected recipes for 360 medicines. One of the recipes is the example of an eye medicine from Bald’s Leechbook. Medieval doctors used this medicine to treat something called a wen in the Old English language. Researchers believe that a wen is an old word for something modern doctors call a sty, a painful red swelling that can form on eyelids.
A common cause of styes is the bacteria known as Staphylococcus aureus. Illnesses caused by this bacteria are more commonly known as staph infections. Most of the time, these staph bacteria live harmlessly on people’s bodies. However, if a person’s immune system is weakened, he or she can become susceptible to staph infections. One strain of this staph bacteria causes a disease that resists normal antibiotic treatment. In their study, the AncientBiotics researchers found that eye medicine from Bald’s Leechbook was especially effective at eliminating this staph infection.
Connelly believes that there is great potential in AncientBiotics’s research. “Our research is in the beginning stages, but it holds exciting potential for the future,” she says.
Doctors and Leeches
Some readers might find one part of the title Bald’s Leechbook familiar: the root word leech.
Leeches are a type of worm that live around the world, usually in fresh water. Sometimes after swimming in a lake or stream, people may find these small creatures attached to their skin. After attaching themselves to a host, leeches numb their victims with an anesthetic so they can painlessly feed on the host’s blood. Unlike mosquitos, which also extract human blood, leeches do not carry disease. However, only a few leech species are interested in people. “Very few of them are interested in feeding on human blood,” says parasite expert Mark Siddall.
Surprisingly, the root word leech in Bald’s Leechbook has a somewhat different source. The word leech comes from the Old English word laece, which was a word for doctor or physician. Until late in the nineteenth century, doctors attributed many diseases to bad blood in their patients’ bodies. Doctors would treat ailments through bloodletting, or draining blood from a patient’s body. Leeches were a common way of removing a patient’s blood. Since doctors so often used them to treat patients, physicians themselves became known as leeches.
As doctors learned more about the real causes of disease, bloodletting with leeches was abandoned in favor of treatments supported by scientific evidence, such as antibiotics and surgery. However, these small creatures still have a place in some modern medical treatments.
For example, doctors use leeches to help patients who have recently had severed body parts reattached to their bodies. When surgeons reconnect a body part such as a finger, they are able to reconnect a patient’s arteries, but not their more tiny veins. While arteries bring fresh blood from the heart to parts of the body, veins instead carry the old blood away.
Since the veins in the reattached body part cannot provide proper circulation, that part may become congested with blood, die, and have to be removed. However, doctors are able to save these reattached body parts by using leeches. Leeches are applied to the affected body part, and the small worms are able to drain it of old blood. Leeches are applied until the body rebuilds its own circulation network, which takes about three to five days. On average, a leech will feed on human blood for about 30 minutes. A single meal consists of about a half an ounce of blood.
See pages from Bald’s Leechbook online at the British Library.
Learn more about how doctors still use leeches to help patients at PBS.
Images and Sources
Bald’s Leechbook Page Photo: Holt.
Bald’s Leechbook Page Photo License: Public domain