Maggot Therapy: Ancient Remedy for Modern Medicine

Devon M. Fagel, JDSurgery Clerkship, YSM III

September 23, 2009

Patient Presentation• CC: 54 yo female presented to ED with foul smelling wound and

“something” coming out of dressing.

• HPI: Difficult and complex case of neuropathic patient with failure of 2 prior surgeries as well as malunion, nonunion, pseudoarthrosis, deep infection involving all four compartments, noncompliance w/ weightbearing and poor diabetic control. Admitted for operation on 9/2/09 for treatment of left foot and anklebone lesions in the setting of deep bone infection (probable osteomyelitis). External fixator was placed to obtain reduction of pilon fracture. Patient made aware that if she developed uncontrolled infection, below-knee amputation would be recommended. Scheduled for follow on 9/8 which she missed. Seen in the ED on 9/17.

• PMH: Uncontrolled DM type 2, HTN, hep C, hep B, hepatomegaly and splenomegaly.

Medial View 1

Medial View 2

Lateral View 1

Lateral View 2

History of Maggot Therapy

• Early Use - 2,000 BC - 1860s

• Modern Use - 1920s - 1940s

• Reintroduction - 1990s

• FDA Regulation - 2004

Early Descriptions of Maggots

• Bible contains first citation of myiasis– “My body is clothed with worms and scabs, my skin is broken and festering…” Job 7:5

• Anthropologists suggest Mayans utilized maggots– “The Maya soaked dressings in the blood of cattle and exposed them to the sun before applying

them to certain lesions, expecting the dressings to squirm with maggots.”

• Napoleon’s surgeon observed the benefit of larvae– “Baron Dominique Jean Larrey’s written observation clearly described the role of the blue fly

larvae in removing only dead tissue leaving remaining healthy tissue behind.”

• Surgeon John Zacharias first to therapeutically use maggots– “During my service in the hospital at Danville, Virginia, I first used maggots to remove the decayed

tissue in hospital gangrene and with eminent satisfaction. In a single day, they would clean a wound much better than any agents we had at our command. I used them afterwards at various places. I am sure I saved many lives by their use, escaped septicaemia, and had rapid recoveries.”

Modern Use of Medicinal Maggots• During World War I, Dr. William S. Baer, an orthopedic surgeon, observed

soldier left for days on the battlefield after sustaining compound fractures of the femur and large abdominal flesh wounds. Despite his injuries he arrived at the hospital afebrile and survived at a time when the death rate for such an injury was approximately 75%.

– “…thousands and thousands of maggots filled the entire wounded area… [after removal] there was practically no bare bone to be seen and the internal structure of the wounded bone as well as the surrounding parts was entirely covered with the most beautiful pink tissue that one could imagine.”

• While at Johns Hopkins in 1929, Dr. Baer applied maggots to 21 patients with chronic osteomyelitis and observed rapid debridement, reductions in pathogenic organisms and alkalinization of the wound area. All patients were completely healed and released after 2 months of maggot therapy. His colleagues posthumously published his results in a groundbreaking JBJS paper in 1931.

• Lederle pharmaceutical company began producing “Surgical Maggots.” Between 1930-1940, more than 100 papers were published on maggots for use in osteomyelitis, sub-acute mastoiditis, abscesses and burns.

Reintroduction of Medicinal Maggots

• By the 1940s more than 300 American hospitals used maggots however after WW II and the discovery of penicillin, many viewed the practice as outdated.

• In 1989, Dr. Ronald Sherman established fly breeding facilities at the VA in Long Beach, CA to reintroduce maggot therapy due to growing problem of antibiotic-resistant bacteria and soon initiated a controlled clinical trial for spinal cord patients with pressure ulcers who had failed to control their wounds with conventional methods.

• In 2004, the FDA granted permission to produce and market maggots for use in humans as a prescription only medical device for “debriding non-healing necrotic skin and soft tissue wounds, including pressure ulcers, venous stasis ulcers, neuropathic foot ulcers and non-healing post surgical wounds.”

• In 2006, approximately 50,000 treatments were applied to wounds. Today over 4,000 healthcare practitioners at 800 US centers using maggot therapy.

• In 2007, prelim trial was found to successfully treat patients whose wounds were infected with MRSA however the final results have yet to be published.

Biology of Flies & Maggots• Maggots are fly larvae, hatch from eggs laid by adult female flies.

• Thousands of species of flies. Some feed on plants or animals or even blood. Some feed exclusively on necrotic tissue while others do not discriminate between live or dead tissue.

• Flies that feed on necrotic tissue lay their eggs inside the wound. Myiasis refers to infestation of a live animal by maggots.

• Flies most often used for maggot therapy are blow flies (Calliphoridae) and the species used is the green blow fly (Phaenicia sericata).

Blow Fly Life Cycle

Blowfly Birth

Application of Maggot Wound Dressing

• Maggots are contained in a cage-like dressing over the wound for two days and may either move freely in the cage or be contained within a sealed pouch.

• Dressing must be kept air permeable as maggots are aerobic.

• Maggots are often satiated within 48 hours and then start to leave the wound at a considerably larger size.

• Multiple 2-day course treatments may be administered depending on severity of the wound.

• Maggots cannot reproduce in the wound as they are still immature. They must mate as adult flies to reproduce.

Mechanism of Action• Debride wounds by eating necrotic tissue leaving behind healthy tissue

– Maggots work around the clock at a microscopic level carefully dissecting dead from living tissue.

– Eat by extracorporeal digestion, secreting proteolytic enzymes that liquefy necrotic tissue the absorb the product.

– In the process, maggots molt twice increasing in length from 1-2mm to 8-10 mm and tripling their girth.

• Disinfect the wound by antimicrobial secretions

– In 1957, a report in Nature found that maggots secrete phenylacetic acid, phenylacetaldehye, calcium carbonate, urea and proteolytic enzymes. Bacteria resistant to these secretions may be ingested and lysed within the maggots.

– In 2008, a report in the Journal of Medical Microbiology investigated in vitro activities of larval secretions against bacterial strains that frequently occur in chronically infected wounds and found that maggots are particularly successful for treatment of wounds infected with Gram-positive bacteria (Staph aureus) but less so against Gram-negative bacteria.

– Some suggest maggot therapy is a cost-effective method for managing MRSA infection.

• Stimulate wound healing– Several studies have shown maggots ramp up host epidermal growth factor and IL-6

– Secretions stimulate proliferation of fibroblasts, chondrocytes and synthesis of cartilage-specific type II collagen.

– Secretions also contain allantoin (commonly found in shaving products) which soothes skin.

Other Considerations• Cost-effectiveness

– A recent study by the National Health Service in the UK found that debridement with maggot therapy of leg ulcers have similar costs to treatment with hydrogel.

• Limitations of maggot therapy– Wound must be moist and exudating with sufficient oxygen supply (though dry wounds

which otherwise unsuitable for therapy may be moistened with saline soaks).

– Maggots have a short shelf life preventing long term storage.

– Patients and doctors may find maggots distasteful at first however they can be enclosed in opaque polymer bags.

– Patients may feel a tickling sensation which can be minimized by tighter application of the dressing.

• Legal issues with myiasis– Patient A was receiving rehabilitation services from Montowese at the time she missed

her follow-up appointment 7 days before presentation in the ED. Several nursing homes and rehabilitation centers have been found negligent for failing to address wounds infected with maggots.