Quoted from The Hundred-Year Lie:

For centuries tribal peoples in Central America, Burma, Australia, and elsewhere used maggots and leeches for healing in their traditional medical practices. During most of the twentieth century Western medical “experts” ridiculed this use of flesh-eating maggots and bloodsucking leeches as examples of primitive barbarism and superstitious ignorance.

These tools of ancient wisdom have finally been rediscovered by medical science because their high-tech treatments for wounds sometimes fail in cases where maggots and leeches succeed. The turnaround in Western medicine’s attitudes began in the early 1990s as a result of studies conducted by Ronald Sherman, who raised maggots in his laboratory at the University of California at Irvine and tested them on hard-to-treat infected wounds.

Maggots not only eat dead flesh while ignoring living tissue, they secrete chemical substances that destroy bacteria and stimulate the growth of healthy tissue. While they do inspire some understandable squeamishness on the part of humans, they are incredibly effective and cheap tools for healing. Diabetics who develop foot ulcers, for instance, might spend thousands of dollars on high-tech treatments and surgeries that fail, compared with a pittance spent on a few maggots that save the foot from amputation.

Medical studies have found maggots to be twice as effective as modern medicine at cleansing dead tissue from wounds, and patients treated with maggots spend many fewer days taking antibiotics and other drugs. At the University of Miami Cedars Wound Center, where maggots are now routinely used, the director Robert Kirsner calls them an indispensable tool because “maggots do work very well.”

Leeches play a similarly new but important role in modern medicine by healing hard-to-treat cases of surgically reattached or transplanted body parts. They drain excess blood from surgical areas and naturally inject patients with a healing chemical cocktail that includes an anesthetic, an antibiotic, an anticoagulant, and a substance that is effective at dilating blood vessels to enhance blood flow. Microsurgeons say that leeches have become their most important secret weapon in restoring blood circulation and insuring the success of problematic surgeries.

Fitzgerald, Randall. The Hundred-Year Lie: How to Protect Yourself from the Chemicals That Are Destroying Your Health (pp. 210-211). Plume. Kindle Edition.