Maggots Help Heal Diabetic Wounds

Creepy-Crawlies Just What the Doctor Ordered for Wound Debridement

Type 2 diabetics with painful leg wounds now have an additional treatment option- maggots. At first, placing maggots on open wounds may seem like a dreadful treatment, but this option is actually much less painful than the alternative.

How Wounds Develop on Diabetic Legs

After 10 to 20 years of poor control of their blood sugars, many type 2 diabetics start having major problems with skin wounds in their legs. Usually the problem at first is poor circulation in the veins of their their legs. This complication of diabetes presents the opposite symptoms of the much more widely publicized condition known as peripheral arterial disease (PAD).

Diabetics who have venous insufficiency usually feel better when they get up and around. Walking makes their legs feel better. The poor circulation in the legs at first causes just a constant itch that is much worse after showering or heating the leg. Then the skin on the legs gets so dry that it turns brown. Usually a misadventure with a diabetic skin treatment product makes the legs break out in eczema, and then tiny holes in the skin get infected. The poor circulation under the legs makes them a prime target for bacterial infection.

Diabetic foot and leg ulcers can also be started by poorly fitted socks and shoes. Footwear rubs against the skin and causes a blister. The blister is not noticed and is not treated, and it becomes infected. When the infection is limited to the skin, it is relatively easy to treat, but some infections take only a few days to penetrate muscles, tendons, and bones. Diabetics who have peripheral neuropathy may never feel initial pain from the infection.

Half of All Diabetics With Leg and Foot Wounds Eventually Need Amputation

An alarmingly large number of  diabetics who develop foot and leg wounds eventually have to have an amputation of the limb. The deeper the wound, the more important it is to keep it clean. When infection reaches the bone, a painful procedure known as debridement is necessary to remove tiny bits of bone and muscle that may be infected and out of reach of antibiotics. In debridement, a surgeon strips out infected bone or tendons to keep a wound clean in the hopes that eventually it may heal.

Debridement is accompanied by treatment with multiple antibiotics, usually for nine months to a year. Many of the antibiotics used to treat infected wounds cause anemia, nausea, and vomiting. Some also cause serious skin reactions.

In diabetics who also have problems with kidney function, antibiotic treatment increases the risk of kidney failure. This is especially a problem when the infectious agent is methicillin-resistant Staphylococcus aureus (MRSA), which usually has to be treated with an antibiotic known as vancomycin. Kidney damage is common with the use of vancomycin.

When there is a tradeoff between gangrene of the foot and having to go on dialysis, doctors will usually sacrifice the foot or leg to save the kidneys. This happens in about 50% of all cases of diabetic leg and foot wounds that go deeper than the skin. But doctors keep searching for ways to remove infected tissue without the horrible side effects of potent antibiotics.

Bugs as Drugs for Diabetics

Recognizing that diabetics need better treatments than debridement and antibiotics to save their limbs, Dr. Lawrence Eron of the Kaiser-Pemanente Hospital in Honolulu and the University of Hawaii has been experimenting with maggots, wriggly fly larvae that normally grown in rotting flesh.


Dr. Eron and colleagues recruited 37 diabetics who had leg wounds that had failed to heal over as much as five years of treatment. They placed 50 to 100 maggots in each wound and encased the wound with nylon mesh, material like panty hose. Every two days the doctors replaced the maturing maggots with new larvae, up to 10 days on average.

Twenty-one of the twenty-seven patients in the study had successful outcomes, defined as elimination of infection, complete removal of dead tissue, closure of the wound by at least 75%, and formation of new collagen for complete healing of the injury. Five patients in the study had infections with MRSA, but they too recovered after treatment with maggots. The patients who did not get a good result had problems with bleeding or infections in their bones that could not be reached by the maggots.

Already an Established Treatment Elsewhere in the World

The Hawaii study results have not been vetted by peer review, but there are actually many studies of the use of maggots in wound healing already reported in the medical literature. There have been two studies of maggots for treating pressure ulcers, two studies of maggots for treating venous ulcers, and four studies of maggots for treating diabetic foot ulcers.

Dr. Eron's method of applying maggots was to place them on a wound and to let them crawl around freely, keeping them in the wound with a nylon mesh. In Denmark, doctors at the Copenhagen Wound Center use a containment device known as a biobag. The maggots never leave the bag, feeding on dead flesh through the mesh. This way the the bag can be lifted at any time for inspection of the wound, and it is not necessary to wash the wound with saline solution to pull maggots out of the flesh at the end of treatment.

Maggots do their work by spitting out enzymes that liquify dead tissue. They slurp up the liquified dead flesh and bacteria along with it, and the digestive juices in their stomachs kill bacteria that continue to cause skin infection (including some kinds of bacteria that cannot be treated with antibiotics). Their urine contains ammonia that stops bacterial growth, and their saliva breaks up the "glue" that holds bacteria to flesh. The idea of maggots eating, urinating, and defecating in your flesh may be disgusting, but those maggots often prevent amputation.

80% Reduction of Amputation Rates in Denmark

The Wound Center at Bispelbjerg Hospital in Copenhagen has used maggots to treat leg and foot wounds in 300 patients since 2002. They report that maggot therapy has reduced amputation rates by 80%, and that the average cost of treatment per patient is 83% less since they started offering maggot therapy. The best results for the use of fly larvae for debridement are for wounds at the heel. Surgeons have difficult separating healthy tissue from dead tissue at this location on the foot, but flies do not.

There are some people who seek treatment at the Bisplebjerg Hospital who cannot be treated with maggot therapy. Maggots are not especially helpful for wounds on the toes when the foot simply does not have enough circulation for healthy tissue to re-form. They will not feed on dry wounds, and they cannot digest Pseudomonas bacteria. About 20% of wound patients have to be treated with traditional techniques. But up to 80% of diabetic wound patients may be candidates for maggot therapy.



Why aren't maggots used everywhere for the treatment of diabetic skin wounds? Even though some centers report great success, there have only been 1,000 patients treated with this method worldwide. Conservative caregivers look for greater experience with the technique before trying it on their patients—after all, amputation always removes dead tissue.