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Return Of The Maggots
Last reviewed and revised by Faculty of Harvard Medical School on December 3, 2009
By Harold J. DeMonaco, M.S.
Massachusetts General Hospital
Maggots have joined leeches as God's less-than-cuddly creatures that are making a comeback in medicine.
The U.S. Food and Drug Administration has approved the medical use of the larval form of the common housefly, also known as maggots. Medicinal use of maggots goes back to the sixteenth century, and although they recently have been used sporadically for medicinal purposes, the FDA has formally condoned the use of maggots to remove dead tissue from non-healing wounds.
Chronic skin ulcers continue to be very problematic, despite advances in our understanding of biology, improved drugs and surgical techniques. Non-healing bed sores and diabetic skin ulcers can be very difficult to treat, often requiring an extraordinary amount of time and expense. They are also quite common. For example, over 600,000 patients a year are treated for diabetic foot ulcers. Therapy for a single ulcer may last for many months and cost thousands of dollars. Despite all therapeutic attempts to heal an ulcer, definitive treatment sometimes requires amputation. A major problem in skin-ulcer treatment is the presence of dead tissue in the wound. Dead tissue inhibits healing and promotes infection. Doctors can surgically remove the dead tissue, but there is always some amount of live tissue that is sacrificed in the process. Topical drugs applied directly to the wound to remove the dead tissue may help, but they do not always work. So, new therapies are needed. Maggots are actually very well designed for this purpose.
Maggots only eat decomposed tissue, leaving healthy tissue alone. They secrete ammonia and calcium carbonate, encouraging wound healing, as well as enzymes that dissolve dead tissue. And as if that were not enough, they also eat bacteria. The maggots used in medicine are the larval form of the common blowfly, a fairly large green-bodied fly that can be found in most homes. While everyone knows that the flies are not the neatest or cleanest of creatures, therapeutic maggots are specially bred for medicinal purposes and do not harbor infectious agents.
Maggots are not the right therapy for all wounds, so their use is a bit limited. Perhaps the biggest limitation is the yuck factor. Not many doctors, nurses or patients are comfortable with the thought. When they are used, maggots are placed on the wound and a special dressing or bandage is put over the wound. The bandage allows air in while covering the good skin around the wound. The maggots are removed in two or three days and replaced with new and, hopefully, hungry maggots. For most patients the treatment is painless, although the maggots do move around a bit under the dressing.
Under the right circumstances, maggots can be very effective and efficient. Rather than wound healing taking months and costing thousands of dollars, treatment with medical maggots can be performed with much less cost and usually over a period of days rather than months. In some cases, the ability of maggots to promote healing has saved limbs from being amputated.
Both maggots and leeches have been maligned by society but are now being recognized as valuable in medicine. So, the next time you swat a fly, think about the number of people who could be helped by its offspring.
Harold J. DeMonaco, M.S., is senior clinical associate in the Decision Support and Quality Management Unit at the Massachusetts General Hospital and is currently a Visiting Scholar at the MIT Sloan School of Management. He is author of over 20 publications in the pharmacy and medical literature and routinely reviews manuscript submissions for eight medical journals.