The Healing Power of Maggots

By Carl Zimmer|Sunday, August 01, 1993
Doctors are rediscovering a disgusting but true bit of folk wisdom: maggots make a great cure for infected wounds.

Grady Dugas, a physician in Marion, Louisiana, was at a loss. His patient, a bedridden 80-year-old man, had developed terrible bedsores, some of them an inch deep, on his heels, hips, and buttocks. Infection had set in, and the conventional therapies--antibiotics and surgical removal of dead tissue--had failed to stop it. Dugas figured he’d have to amputate both feet at least.

But then he remembered that his grandmother, a diabetic who had also suffered from sores on her legs, had undergone a different sort of treatment in the 1930s. Dugas called Jeffrey Wells, an entomologist at Louisiana State University. A week later Wells arrived in Marion with 8,000 blowfly eggs.

Dugas put the eggs on the patient’s bedsores, just as doctors had done with his grandmother’s infections. The eggs hatched as maggots, fed on the infected tissue, turned into flies, and flew away. Dugas applied more eggs. Within four weeks the patient’s sores were clean and filled with healthy tissue. Far from preparing to amputate, Dugas sent the man to a local hospital to receive skin grafts.

The healing power of maggots is not, properly speaking, news. Human beings have discovered it several times. The Maya are said to have used maggots for therapeutic purposes a thousand years ago. As early as the sixteenth century, European doctors noticed that soldiers with maggot- infested wounds healed well.

The modern heyday of maggot therapy began during World War I, when an American doctor named William Baer was shocked to notice that two soldiers who had lain on a battlefield for a week while their abdominal wounds became infested with thousands of maggots had recovered better than wounded men treated in the military hospital. After the war, Baer proved to the medical establishment that maggots could cure some of the toughest infections. In the 1930s hundreds of hospitals regularly used maggot therapy. But then sulfa drugs, the first antibiotics, emerged around the time of World War II. Maggot therapy quickly faded into obscurity.

The switch may have had more to do with the weak stomachs of practitioners than with good science. And in the past decade, as doctors have begun to realize that maggots are still superior to drugs in some respects, the squirming larvae have enjoyed a quiet medical renaissance. Maggots are more effective and cheaper than a lot of incredibly expensive commercial compounds, says Jane Petro, a surgeon at New York Medical College.

Petro uses maggots primarily to treat tumor-killed tissue and certain burns in people who would be endangered by surgery. But maggots are also good at fighting bone infections, which can occur when a fractured bone breaks the skin. Bones contain few blood vessels, so antibiotics almost never reach infections in them. Maggots clean out bone infections with a 90 percent success rate.

Maggot therapy begins with getting the right kind of maggots. Only the maggots of blowflies (a family that includes common bluebottles and greenbottles) will do; they devour dead tissue, whether in an open wound or in a corpse. Some other maggots, on the other hand, such as those of screwworm flies, eat live tissue. They must be avoided.

When blowfly eggs hatch in a patient’s wound, the maggots eat the dead flesh where gangrene-causing bacteria thrive. They also excrete compounds that are lethal to bacteria they don’t happen to swallow. Meanwhile, they ignore the live flesh, and in fact give it a gentle and growth-stimulating massage simply by crawling over it. When they metamorphose into flies, they leave without a trace--although in the process they may further disconcert hospital personnel.

Squeamishness is one reason doctors still use maggots only as a last resort. It just goes back to the disgust factor, says Petro. According to Wells, If you read some of the case studies, the report is, ‘We tried everything; then we finally tried the maggots, the wounds got better--and the patient died.’ It’s only used on people who are in very bad shape. With the guy I worked with, nothing had been working for months, and he’s still not out of the woods. I’d really like to know how he’d have responded if we’d treated him immediately.
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