1997 WINNER

The Return of Maggot Therapy

By David Scott

Maggot debridement therapy is the use of live maggots to clean, and disinfect wounds. It is a traditional technique that became obsolete in the middle of this century, due to the advent of antibiotics, which were thought to be cheaper and more effective. Increasing resistance of bacteria to antibiotics, and the little impact that they have on many wounds, has caused a renewed interest in the treatment first used many years ago.

The wound healing properties of maggots have been known for centuries, as soldiers who were injured on the battlefield, were less likely to get infected wounds if infestation with maggots occurred. In fact it was military surgeons who first pioneered maggot debridement therapy. The first surgeon to actually introduce maggots into a wound was J.F. Zacharias during the American Civil War. He was quoted as saying:

"In a single day they [maggots] would clean a wound much better than any agents we had at our command. I used them afterward at various places. I am sure I saved many lives by their use..."

However, the first recorded clinical use of maggots was not until the 1930's, when an orthopaedic surgeon, William Baer, drawing on his experiences of wound infestations in World War I, used maggot therapy to heal wounds following surgery, with a high success rate. But in the 1940's larval therapy was replaced with treatment using antibiotics, which were cheaper, and initially more effective. Since then treatment with maggots has been used occasionally when conventional methods have failed. So in 1989 doctors at the University of California, led by Dr R.A. Sherman, started research into maggot debridement therapy, which is still continuing today.

Maggot therapy is now offered in around fifty hospitals throughout the UK, for various conditions, ranging from burns, to aiding recovery after surgery. The most common uses however are in the cleaning of infected wounds, and for the treatment of pressure sores.

The maggots, up to 600 per application, depending on the size of the wound, are placed directly on the affected area of the skin, and covered with a fine mesh, a dressing and an absorbent pad. This keeps the maggots on the wound and away from healthy skin, as well as containing any dead tissue. The outer dressing can be changed regularly without fear of the maggots escaping. After three to four days the dressing is removed and the maggots flushed out with saline solution. Since it takes a minimum of seven days for the maggots to pupate, there is no chance of the larvae turning into flies.

Under the dressing, the maggots release a mixture of enzymes, chemicals which break down the dead matter before they ingest the resulting liquefied tissue. To an extent they are externally digesting the tissue, before consuming it for food. They will often group together maximising the effect of their enzymes. In feeding they also destroy the bacteria that are causing the infection of the wound, by ingesting them. It is also thought that micro-organisms living within the maggots' guts may actually produce antibacterial agents that kill the bacteria in the wound.

Larval therapy has several advantages over conventional methods of wound management using antibiotics. Although antibiotics do kill the bacteria infecting wounds, they do nothing to clean up the dead tissue, known as slough, nor do they cause granulation, which is the formation of new blood vessels. There is a growing belief among leading physicians, that the lack of functioning blood vessels in and around the wound, limits the antibiotics' ability to reach the affected area, reducing their overall effectiveness. Not only do wounds treated with an application of maggots heal more rapidly than those with antibiotics, they also clean the wound more efficiently.

Maggot debridement therapy has to be seriously considered as a viable alternative to antibiotics, due to the increasing number of bacterial strains becoming drug resistant. This is a problem that is likely to increase in the future, so alternative treatments should be investigated now. But despite these benefits, many people are reluctant to consider larval therapy. The maggots' attraction to dead tissue is the reason why traditionally, maggots have been associated with disease, death and decay, but that reason is also why they are now helping people survive. People also fear the maggots burrowing into healthy tissue, but the larvae used are a non-burrowing species, so these fears and prejudices are unfounded.

Maggot debridement therapy is still very much on trial, it will be several years yet before there will be widespread availability of this technique in hospitals, and perhaps eventually, on prescription. Clinical trials will have to show highly positive results before a treatment as radical as this will gain the full approval of the medical profession.