Entomological Medicine: How One Scientist is Working to Bring Maggot Therapy Into Wider Use

By Jacqueline Kerth

One of my favorite symposia from the Entomological Society of America (ESA) 2020 Annual Meeting was the session titled “Looking for Bugs in All the Wrong Places – Finding Entomology Where You Least Expect it, organized by Laura Higgins, Ph.D., BCE-Emeritus, and Susan Moser, Ph.D. That session featured a diverse group of professionals, mostly non-entomologists, who use insects or insect models in their work. Recently I had the good fortune to work with one of those individuals, a physician who has spent over 40 years studying the use of Lucilia sericata blow fly larvae as a medical treatment for serious wounds, a practice known as maggot therapy.

Ronald Sherman, M.D., M.Sc., DTM&H, sees medicine through the lens of entomology. He received his B.S. in entomology from the University of California, Riverside and his M.D. from UCLA, and he completed his internship and internal medicine residency at UC San Francisco-Mt. Zion and UC Davis, respectively. Sherman then studied clinical tropical medicine at the London School of Hygiene and Tropical Medicine. Upon his return to the U.S, he completed a postdoctoral fellowship in infectious diseases at UC Irvine. It was during this fellowship that he began his clinical studies in maggot therapy.

Sherman continued clinical and basic science research in maggot therapy as a faculty member at the UC Irvine campus until he retired in 2008. Today, Sherman is director of the not-for-profit BioTherapeutics, Education and Research (BTER) Foundation and cofounder of Monarch Labs, a commercial, FDA-regulated laboratory dedicated to making medicinal animals available to all who need them. The term “biotherapy” here refers to the use of living animals as medical treatments or interventions.

Following below is a Q&A with Sherman on the basics of maggot therapy, how he got engaged in this intersection of entomology and medicine, and what the future might hold for adoption of this treatment.

Kerth: How would you define “maggot therapy”?

Sherman: Maggot therapy is simply a controlled, therapeutic myiasis. Myiasis is the name of the condition where maggots are infesting a live vertebrate host. We usually think of maggots as feeding off a dead animal, and that is the norm for many types of fly larvae, especially the blow flies (Calliphoridae). But sometimes the flies cannot tell the difference between a dead animal and the dead tissue of a live animal.

The adult female fly is attracted by the odor of decomposing flesh—what medical professionals call necrotic tissue, and the rest of us call gangrene—and the fly deposits its eggs or larvae there. The larvae excrete their digestive juices, dissolve the dead infected tissue, suck up that liquefied tissue, and rapidly mature. Once satiated—or when they run out of food—then they leave the host.

As I said, when this occurs on a living vertebrate host, it is called myiasis. By controlling the myiasis such that you optimize safety and efficacy, one can ensure a very clean wound from which all of the dead infected tissue has been removed, while the healthy tissue remains intact. That controlled, therapeutic myiasis is what we mean by maggot therapy.

The use of blow fly larvae to clean and heal serious wounds is a valuable but underused medical treatment. Physician and entomologist Ronald Sherman, M.D., leads a nonprofit foundation to support patient care, education and research in maggot therapy. Shown here is an adult fly of the species Lucilia sericata, the larvae of which are used in maggot therapy. (Photo by Joseph Berger, Bugwood.org)

Maggot therapy is a controlled, therapeutic myiasis, says Ronald A. Sherman, M.D. Myiasis is the name of the condition where maggots are infesting a live vertebrate host. By controlling the myiasis to optimize safety and efficacy, one can ensure a very clean wound from which all of the dead infected tissue has been removed, while the healthy tissue remains intact. (Photo courtesy of Ronald A. Sherman, M.D.)

How did you get involved in entomology?

As a child, I was interested in all sorts of natural sciences, but I was most passionate about insects. When it came time to apply for college, I knew that I wanted to train as a doctor in graduate school, but I wanted my undergraduate education to be broad and in other areas that interested me. So, instead of being a biology or biochemistry major like most of my medicine-oriented friends, I chose to major in entomology and minor in music.

Why did you decide to pursue medical research?

I am fascinated by everything about the natural world, and I love problem solving. Biomedical research combines the two. Some of the first research puzzles I wanted to solve were: “Can a living fly larva be made germ-free?”, “How can it be done without killing the maggot?”, and “Can maggot therapy save wounded or gangrenous limbs from amputation that are not already being saved with 21st-century technologies?” Finding answers was both satisfying and relevant; the solutions could be implemented immediately.

While earning your degrees, you volunteered with Native Americans and urban poor in Arizona. How did you come to focus on maggot therapy research?

The motivation to study maggot therapy is the same as what led me to provide health care to Native Americans and the urban poor: I like to fill needs that are underserved. As an infectious diseases fellow in 1989, I was frequently asked to recommend antibiotics for problematic wounds. I suggested that maggots might do a better job cleaning the dead, infected tissue than what we were doing with surgery and antibiotics, though there never had been a controlled study. My professors at the VA Medical Center supported my controlled clinical trials. After seeing the profound benefits of maggot debridement, or wound cleaning, I was hooked.

Ronald A. Sherman, M.D., examines one of 30 cages of flies in his laboratory at the BioTherapeutics, Education and Research (BTER) Foundation. The laboratory collects approximately 500,000 eggs per week, to be used for research or patient care. (Photo courtesy of BTER Foundation)

Ronald A. Sherman, M.D., removes a maggot therapy wound dressing while teaching nurses about maggot therapy for wound care in Long Beach, California, in 1995. (Photo courtesy of BTER Foundation; taken by, and used with permission of, the patient’s wife)

What motivated you to start the BTER Foundation?

There was a lot of resistance to maggot therapy 25 years ago, especially in academic medicine. Although more patients were asking for treatment—a chance to save their legs from amputation—education and access to maggot therapy was being stifled. In 2003, a group of us created the BioTherapeutics, Education and Research Foundation to support education and research in maggot therapy as well as other under-represented biotherapies.

Any advice for scientists who are thinking of pursuing entomology and medical research?

Follow your passion. There are many positions and projects that intersect the fields of entomology and healthcare. It may take a lot of work and time and perseverance—there may be heartache and loneliness along the way—but only by traveling off the beaten path will you see new vistas and make new discoveries.

Moving forward, where would you like to see medical entomology and maggot therapy go?

During my formal education in medical entomology, I was taught only about the insects that caused illness. I hope students now and in the future learn something about some medical benefits of insects, too. Regarding the future of maggot therapy, I would like to see more progress in making maggot therapy acceptable to patients and healthcare workers. In published studies of patients with non-healing wounds scheduled for amputation but given maggot therapy as a last resort, maggot therapy was shown to save those limbs in 50 percent to 70 percent of patients. With over 100,000 amputations performed every year just in Americans with diabetes-related wounds, you would think that most of them would be offered a trial of maggot therapy before amputation. But less than 2 percent are offered a trial of maggot therapy to save their limbs. Correcting that missed opportunity to save a limb has been a great challenge, but it is also an opportunity to improve the lives of hundreds of thousands of people.

Sherman has shown that new solutions can come from combing two passions and continuous hard work. Maggot therapy is now being used around the world to treat wounds that previously were thought to be un-healable. To find out more about maggot therapy, see the BTER Foundation’s website and other resources below.

Jacqueline Kerth is a student majoring in life science at Soka University of America in Aliso Viejo, California, and a research intern at the BioTherapeutics, Education and Research (BTER) Foundation in Irvine, California. Email: jacquelinekerth@gmail.com. Ronald A. Sherman, M.D., M.Sc., DTM&H, is director of the BTER Foundation. Email: rsherman@bterfoundation.org.