A new study has found that just one week of maggot debridement therapy (MDT) clears necrotic tissue more effectively than conventional debridement in patients with chronic venous ulcers.

Researchers at the Centre Hospitalier Universitaire (Caen, France) conducted a prospective study involving 119 hospitalized patients (mean age 73) with a nonhealing, sloughy lower-leg ulcers 40 cm2 or smaller, less than 2 cm deep, and an ankle brachial index of 0.8 or higher. Twice-weekly maggot therapy was administered in a polyvinyl alcohol membrane bag containing 80 sterile Lucilia sericata maggots that were able to access wound surfaces through the bag; control patients had surgical debridement under topical anesthesia three times each week. All patients wore blindfolds during the treatment, and were unaware of the difference in treatment schedules. The main outcome measure was percentage of slough in wounds at day 15.

The results showed that there was a significant difference between groups at day 8 (54.5% in the MDT group and 66.5% in the control group), but there was no difference between the groups in percentage of the necrotic tissue on the wound at day 15 (55.4% versus 53.8%). In fact, the wound surface area had increased by 14.6% in patients receiving maggot therapy and had decreased by 8.2% among patients treated with surgical debridement, suggesting that a second week of maggot therapy could be deleterious. The study was published early online on December 19, 2011, in Archives of Dermatology.

“Contrary to surgical debridement, maggot therapy is easy, safe, painless, and well accepted by the patient,” concluded lead author Anne Dompmartin, MD, PhD, and colleagues of the department of dermatology. “There is no benefit in continuing the treatment after one week, and maggot therapy does not improve the time to wound closure, which is why it should be stopped when debridement is achieved.”

MDT, also known as larval therapy, biodebridement, or biosurgery, involves the intentional introduction of live, disinfected maggots (fly larvae) into the nonhealing skin and soft tissue wounds for the purpose of debriding the necrotic tissue within the wound. The maggots are contained in a cage-like dressing or a sealed pouch, with the wound floor acting as the bottom of the cage or pouch. When the maggots are satiated, they become substantially larger and seek to leave the site of a wound. Multiple two-day courses of maggot therapy may be administered depending on the severity of the non-healing wound.

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