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October 2001
Vol. 4, No. 10, pp 19, 21, 23.
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Medicinal maggots

Many hospitals have discovered this “natural” way to clean wounds.

An older diabetic patient with a chronic foot ulcer is told that unless this last treatment works, the foot will have to be amputated. In a last ditch effort to save his foot, the patient agrees. Doctors pry open the ulcer on his foot and cover it with a copper-mesh bandage full of 1- to 3-mm-long maggots. Immediately, the starving larvae wiggle into the open wound and begin devouring the necrotic tissue inside the foot. The patient, conscious during the procedure, complains of a “tickling” sensation caused by the feasting larvae. Three weeks later, he walks out of the hospital with his right foot totally healed. (For an example, see Maggot Therapy, Case 2.)

This scenario is not a scene from a hospital television show or an ancient tribal method of treating foot ulcers. On the contrary, it is a common result of the modern-day procedure called maggot debridement therapy (MDT)—or, more commonly, maggot therapy—that is practiced in more than 150 hospitals in the United States and 1000 centers worldwide.

The use of maggots to treat wounds dates to ancient times. William S. Baer is considered to be the father of modern MDT because he devised a way to sterilize the maggots. This helped reduce the infections that had killed MDT patients during the Civil War. During World War I, Baer observed that when the open wounds of injured soldiers were maggot-infested and unattended for several days, they remarkably still had healthy, pink granulated tissue. Baer later found that the maggots selectively debrided the necrotic tissue in soldiers’ wounds but left the healthy tissue untouched.

Maggot methodology
Not just any fly larvae can be used to treat infections, though. Some species of larvae can be detrimental to the wounds of patients. For that reason, doctors prefer to use Lucilia sericata, or greenbottle blowfly larvae. Blowfly larvae eat only dead tissue and starve on healthy tissue, making them ideal for medicinal use.

In early applications, sterilizing the larvae was a major problem. Doctors had to first bathe the eggs in bleach and then soak them in mercuric chloride or formaldehyde. The bandages, gaudy and cumbersome for the patients, were held in place with either surgical tape or Unna’s paste—made of zinc oxide, gelatin, glycerin, and water. Other problems that doctors faced included the maggots escaping during the application process and the leakage of toxic waste secreted by the maggots into the wound, which led to infections such as tetanus.

Today, commercial and research laboratories produce sterile larvae. And instead of the bulky gauze bandage, a form-fitting cast with a nylon net to corral the larvae is placed over the wound. An absorbent pad put on top of the netting soaks up the larvae’s toxic waste products. The number of larvae used has also changed. Early prescriptions ranged from 5–6 maggots for a fingertip injury to 500–600 for a more serious wound. Today, the scientific standard of 10 larvae/cm2 is used.

Doctors recommend cleaning and rinsing the wound with warm saline and reapplying the larvae every three days until the wound is healed. MDT can be used with conventional antibiotic treatments.

However, despite better sterilization and control procedures for the larvae, risks are still associated with MDT. The larvae can develop into flies, which present a risk of infection for the hospital.

Prejudice or practice
Despite its success, MDT is a controversial topic among doctors and medical staff. “Many [doctors] have never tried it, are not willing to try it, and do not believe it has any place in our hospital,” says Ronald Sherman, assistant professor of medicine in residence at the University of California, Irvine. But Sherman adds that doctors who have used MDT have been pleased with the results and continue to use it.

Chris Attinger, professor of plastic surgery and director of the wound-healing center at Georgetown University Hospital (Washington, DC), is one of the few doctors who champion MDT. “My feeling is that it is the best debrider on the market and makes anything pharmaceutical look ridiculous,” says Attinger, “If I had my druthers, I would use them all the time.” He believes that some doctors hesitate to use the treatment because of the ridicule they may experience from their colleagues, something Attinger knows all to well. “[Colleagues] look at you with bewilderment and think you are totally out of your head,” he says.

If MDT works, then why aren’t more patients and doctors using the therapy? “Society’s viewpoint toward bugs is the reason [MDT] isn’t used more,” says Attinger. “People still don’t like the idea of bugs crawling on someone’s leg,” he says. Sherman agrees. “We have spent the past many decades equating health with cleanliness; disease with filth,” he says. “Unfortunately, society equates maggots with the look and smell of their garbage.”

Many doctors agree that increasing the acceptability of MDT among physicians and hospital staff would require major reeducation about maggots. “Nurses hate [maggots],” says Attinger, “and are often left to dress and apply the maggots to the wounds; you need to have someone with a strong stomach to kill [the maggots] when it comes time to change the dressing.” However, getting physicians to use the therapy on a regular basis may be a lost cause. “Some physicians just aren’t ready to ask for help from a maggot,” says Sherman.

A standard or alternative medicine?
There are a number of theories on how maggots “work”, or distinguish between dead and healthy tissue in wounds. The most common belief is that they secrete antimicrobial waste products such as ammonium, calcium, or other bicarbonates that break down only the necrotic tissue in wounds; these secretions also change the alkalinity of the wound to help it heal. Some doctors believe that the mere action of maggots crawling over the wound stimulates the healing process.

Because doctors are not sure how maggots help to heal a wound, many classify MDT as alternative medicine and are reluctant to recommend it to their patients. Sherman disagrees with the classification process. “I don’t know that an understanding of the mechanisms has anything to do with the classification of therapy,” says Sherman, “There are many pharmaceuticals whose mechanisms of action are still unknown, yet their efficacy and use have made them standard treatment.” The fact that MDT works with no ill effects on patients is enough for many doctors. “It used to be the old way of doing things, and some of the old things work very well,” says Attinger.

MDT is often used as a last-minute option, something that Sherman believes is a critical fault among doctors. “Unfortunately, by the time most people think of using maggots, they have failed four, five, or more standard treatments, and by that time, the underlying damage (poor circulation, advancing infection, etc.) has progressed to a point that the probability of salvage by maggots is small,” says Sherman. Instead, he recommends using MDT sooner, after two or more failed conventional treatments.

The future
The arrival of antibiotics in the 1940s led to a 60-year hiatus for the use of maggots and the first of many MDT alternatives for doctors and patients.“There are always alternatives, such as the topical debriding agent Accuzyme and, of course, surgery,” says Attinger, “but they are painful and take forever.” He believes that the two methods, MDT and surgery, are equally effective but that patients need to decide what is best for them. “[Maggots] are ideal, and there is no pain, but the question is how do people handle the larvae,” he says.

Although MDT is successful and highly recommended by its supporters, it will probably never become a standard practice in the medical field. Doctors like Sherman, who regularly use MDT, want it to be an earlier option for patients.Sherman believes that if patients were initially informed of their alternatives, including MDT, 95% would choose MDT. His patients, he says, “often commented that maggot therapy could not be any worse than the treatments they had already endured.”

Further reading

Wilder Damian Smith is a staff editor of Analytical Chemistry. Send your comments or questions regarding this article to mdd@acs.org or the Editorial Office by fax at 202-776-8166 or by post at 1155 16th Street, NW; Washington, DC 20036.

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