Maggot’s therapy for treatment of Leg ulcers

Background

The larval form of flies in their developmental life cycle are called as maggots in layman language. Maggots are considered as scavengers that take shelter on dead, decaying body or putrefying tissue. They thrive on such environments and need warm and dry areas to thrive and sustain life. Curiously, they have been used as a therapy for the chronic, non-healing leg ulcers, ulcers due to diabetes, varicose vein, pressure ulcers and ulcers secondary to trauma. It appears very bizarre, eccentric idea to apply maggots as a therapy for treatment of leg ulcers. Maggots were used as a treatment for leg ulcers since 19^th century. If the recent reports were to believe it is true and they are better in treating some MRSA infection (Methicillin resistant Staphylococci Aureus), gas gangrene ulcers due to Clostridium welchii, MRSA infections are very resistant infections to treat and combating them even with most sophisticated antibiotics is challenge and some time even remain infected for life with bone abscesses and septicaemia (infection in blood and other systems in the body). Not all maggots are used therapeutically to treat venous ulcers in the leg. The common maggots used are a species called as Lucilia Sericata (green bottle blowfly).This flies maggots do not have teeth and will not burrow or attack normal tissue but eats up only dead tissue. All flies we know have a pair of functional wings and that is why are classified as Diptera (di+pteron) or two winged. Diptera was a named by Aristotle and a Greek word. These maggots can be facultative parasites (developing in dead and necrotic tissues) or obligatory parasites (thriving on live animals and humans). The maggots which eat or thrive on dead tissues are called (sarcophagi group).The process of larva producing capacity and infestation of these in medical term is called myiasis. Some times these larva can be ingested and inhaled but this process is called Pseuodomysiasis.

History

The earliest history of maggots dates back in bible. In the Bible, Job (Job 7:5) complained `My body is clothed with worms and scabs, my skin are broken and festering'. The Ngemba tribe of New South Wales, Australia, commonly used maggots to cleanse suppurating or gangrenous wounds and it is said that the aborigines traced this practice back to their remote ancestors. Confederate surgeon of Napoleon in French war used this and learnt beneficial effects accidentally. Later a man called J. Zacharias may have been the first western physician to intentionally introduce maggots into wounds for the purpose of cleaning or debriding the wound. He used this during American Civil war. The Hill Peoples of Northern Burma were observed during World War II placing maggots on a wound then covering them with mud and wet grass. The founder of modern maggot therapy is William Baer (1872-1931), Clinical Professor of Orthopaedic Surgery at the Johns Hopkins School of Medicine in Maryland. He^, used maggots on 2 patients in 1^st World War. It was gaining popularity as a therapeutic agent in treatment of leg ulcers and debridement of ulcer. But the advent of discovery of Pencillin by Alexander Fleming in 1940 and later sulphonamides curtailed use of maggots in leg ulcers. It was lost tribe issue until 1990’s when the interest in maggot therapy reappeared. It came in clinical practice in late 1990’s in UK when Princess Wales Hospital, Bridgend used these maggots therapeutically and even started prescribing for clinical use.

Relevance of maggot therapy

We live in a world where emphasis is for firm evidence-based medicine and effective treatment for the therapy we offer to our patients. Though some clinical trials have been carried out they are not prospective randomised clinical trials studies. Until that is not done one can not use maggots as first-line treatment for venous ulcers. It is difficult to carry such studies on ethical grounds and dilemma that is facing the medical fraternity and the large number of population that need to be studied to conclude the study is statistically significant. But the clinical opinion so far favours to use maggot therapy in resistant non healing ulcers, in gangrenous tissues where even amputation was imminent, in Pseudomonas infection, MRSA infection or in case of fulminating septicaemia. The UK Government spends one billion pounds per year for treatment of leg ulcers. All these ulcers can be prevented in already hard-pressed budget and its resources of different countries.

Mechanism of action

Maggots secrete proteolytic enzymes from their secretions and digest the dead tissue and make a soup and then these are ingested by the maggots. This produces debridement of dead or necrotic tissue. It is better than doing the debridement by surgical means. These maggots also kill the bacteria and make the area in the wound sterile. They also secrete juices which limit the spread of infection and make the healing better. The maggot therapy has shown healing rate is better and faster healing with production of granulation tissue which is very important for healing of wounds. They produce fibroblast stimulating chemicals which encourage fibroblasts to start granulation process. But the attempt to grow fibroblasts or to produce fibroblasts from Maggots has so far failed. As good granulation tissue is formed (pink covering over the healing ulcers), the defect is filled and wound finally heals. As fibroblast contacts they form a scar.

Dose of maggots for clinical application

There is no fixed number of maggots one need to apply on wounds. The number of maggots one need to apply depends upon the size of ulcer and amount of necrotic or dead tissue that is present. It may vary from 15 to 200. But they are directly applied on wounds and covered with dressing. The compression bandage is adequate. There are special dressings available for its application. But the wound or ulcer need to be kept moist and cold and well aereated.  The warm and dry condition favours maggots next life cycle that is pupa. That is why maggots are applied for 2-3 days and then removed. It should be applied until wound is healing is active or ulcer is persisting. If it is kept more than 10 days the maggots may turn in to flies which is not desirable.

The maggots are available in sterile form in UK and in USA and not available in India. Soon this may become popular even in India. As far as my knowledge goes they are not available in India.