Maggot debridement therapy (also known as MDT, larval therapy, or simply maggot therapy) is a type of biotherapy involving the introduction of live, disinfected (fly larvae) into non-healing skin and soft-tissue of a human or other animal for the purpose of cleaning out the necrosis (dead) tissue within a wound (debridement), and disinfection.
There is evidence that maggot therapy may help with wound healing.
Medical uses
Maggot therapy improves healing in .
In 2003, the United States Food and Drug Administration (FDA) cleared maggots from common green bottle fly for use as a "medical device" in the US for the purpose of treatment of:
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Non-healing necrotic skin and soft tissue wounds
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Venous ulcer
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Neuropathic foot ulcers
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Non-healing traumatic or post-surgical wounds
Limitations
The wound must be of a type that can benefit from the application of maggot therapy. A moist, exudate wound with sufficient oxygen supply is a prerequisite. Not all wound-types are suitable: wounds which are dry, or open wounds of body cavities do not provide a good environment for maggots to feed. In some cases it may be possible to make a dry wound suitable for larval therapy by moistening it with saline soaks.
Patients and doctors may find maggots distasteful, although studies have shown that this does not cause patients to refuse the offer of maggot therapy.
Mechanisms of action
The maggots have four principal actions:
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Debridement
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Disinfection of the wound
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Stimulation of healing
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Biofilm inhibition and eradication
Debridement
In maggot therapy, large numbers of small maggots consume necrotic tissue far more precisely than is possible in a normal surgical operation, and can debride a wound in a day or two. The area of a wound's surface is typically increased with the use of maggots due to the undebrided surface not revealing the actual underlying size of the wound. They derive nutrients through a process known as "extracorporeal digestion" by secreting a broad spectrum of proteolytic enzymes
Disinfection
Secretions from maggots believed to have broad-spectrum antimicrobial activity include allantoin, urea, phenylacetic acid, phenylacetaldehyde, calcium carbonate, proteolytic enzymes, and many others.
Biology of maggots
Those flies whose larvae feed on dead animals will sometimes lay their eggs on the dead parts (necrotic or gangrenous tissue) of living animals. The infestation by maggots of live animals is called myiasis. Some maggots will feed only on dead tissue, some only on live tissue, and some on live or dead tissue. The flies used most often for the purpose of maggot therapy are blow flies of the family Calliphoridae: the blow fly species used most commonly is Lucilia sericata, the common green bottle fly. Another important species, Protophormia terraenovae, is also notable for its feeding secretions, which combat infection by Streptococcus pyogenes and S. pneumoniae.
History
Written records have documented that maggots have been used since ancient history as a wound treatment.
Joseph Jones, a ranking Confederate medical officer during the American Civil War, stated:
The first documented therapeutic use of maggots in the United States is credited to a second Confederate medical officer Dr. J.F. Zacharias, who reported during the American Civil War that:
He recorded a high survival rate in patients he treated with maggots.
During World War I, orthopedic surgeon William S. Baer recorded the case of a soldier left for several days on the battlefield who had sustained compound fractures of the femur and large flesh wounds. The soldier arrived at the hospital with maggots infesting his wounds but had no fever or other signs of infection and survived his injuries, which would normally have been fatal. After the war, Baer began using maggot therapy at Boston Children's Hospital in Massachusetts.
There were reports that American prisoners of war of the Japanese in World War II resorted to maggot therapy to treat severe wounds.
A survey of United States Army doctors published in 2013 found that 10% of them had used maggot therapy.
Regulation
In the USA: in January 2004, the FDA granted permission to produce and market maggots for use in humans or animals as a prescription-only medical device for the following indications: "For debriding non-healing necrotic skin and soft tissue wounds, including pressure ulcers, venous stasis ulcers, neuropathic foot ulcers, and non-healing traumatic or post-surgical wounds."[Carrie Arnold for Scientific American. April 1, 2013 New Science Shows How Maggots Heal Wounds][ FDA CDRH 510(k) summary ]
Veterinary use
The use of maggots to clean dead tissue from animal wounds is part of folk medicine in many parts of the world.
However, there have not been many case studies done with maggot debridement therapy on animals, and as such it can be difficult to accurately assess how successful it is.
Further reading
External links
