Insects and many other invertebrate animals have been utilised for medicinal purposes for thousands of years if not longer. Now modern clinical science is rediscovering this wealth of therapeutic resources. Generally speaking, insects and other invertebrates may be used whole, for example as dried and powdered formulations in traditional Chinese medicine, for example, or used as living organisms like in the case of medicinal maggots.
The larvae of blowflies (Calliphoridae) better known as maggots are superbly adapted to colonise carcasses and exploit this ephemeral source of food. The carcass environment is laden with germs of all kind and competition for food from fellow maggots and other species is fierce. This resulted in evolutionary adaptations that allow blowfly maggots to cope with, and fight, harmful microbes, and to consume necrotic tissue very fast so that they are able to complete larval development within only a few days. As it happens, blowflies do not only exploit carcasses but many will also visit infected and non-healing wounds in animals and humans. When maggots colonise a wound of a vertebrate animal, we speak of myiasis. In that wound they find very similar conditions to a carcass and so they exhibit the same adaptations that help them thrive on a carcass with remarkable therapeutic benefit to the non-healing infected wound.
These healing properties were noticed by people throughout history and thus maggots have been used in tribal and traditional medicine. However, some of the best historical records of beneficial myiasis and eventually therapeutic medicine comes from military surgeons as far back as the sixteenth century. During the American civil war, John F. Zacharias also noted the good work of maggots and proactively used maggots to treat his fallen soldiers. Modern clinical use of maggot therapy had to wait, though, until the orthopaedic surgeon William S. Baer witnessed the miraculous benefits of maggots in war wounds. Inspired by his wartime experience, he started to treat patients back home at John Hopkins Paediatric Hospital and developed the first production methods for medicinal maggots.
So, what happens when maggots are placed on a chronic infected wound with lots of dead tissue instead of a carcass? They rapidly consume and thereby remove necrotic tissue. By consuming this dead tissue, they take away the food and habitat for bacteria and in the process, they also consume and digest these microbes. Furthermore, antimicrobial compounds in their secretions and excretions kill bacteria and fungi, including antibiotic resistant strains. An added benefit is that the digestive secretions and excretions of maggots also promote the growth of healthy new granulation tissue and blood vessels that are necessary for the supply of oxygen to the wound.
Despite these clearly observable whole-organism benefits, the modern approach in clinical science and drug development is to identify the active compounds and molecules that deliver a therapeutic benefit and to characterise them sufficiently for mass production outside the animal system that produced them in the first place. We can see this trend across a spectrum of animals and medical indications such as anticoagulants from leeches, advanced drugs from venoms, and antimicrobial peptides and growth factors from medicinal maggots.
Of course, there are good technical reasons to focus on one specific molecule or compound for drug development. What is missed or conveniently ignored, though, is the complexity that is inherent in disease processes. Chronic wounds are a prime example as they are the consequence of extraordinarily complex disease processes. Comorbidities such as cardiovascular disease or diabetes predispose patients to injury or they significantly compromise the body’s capacity to respond to injury in a normal healthy way. Wound healing processes are inhibited or malfunctioning leading to chronic inflammation and microbes settle in to take advantage of the confusion, forming complex ecological communities themselves and adding further complexity. Consequently, what we end up with in chronic wounds is complexity which rivals that of any natural ecosystem.
When treating chronic wounds, it makes therefore good sense to note this complexity and to approach it with therapeutics that are similarly complex and adaptive in their mode of action. This means that it may be far more efficacious to use the whole living maggot for wound care rather than one or two of its antimicrobial or growth-promoting factors. Single drugs are not adaptive like a living organism and usually do only one thing at a time, whereas maggots can respond to different and changing wound environments through behavioural and physiological adjustments in real time. A growing body of scientific literature elucidating the therapeutic principles of maggot therapy as well as a good number of clinical studies and case reports support this hypothesis.
Unfortunately, maggot therapy is still not widely understood as a viable alternative to conventional wound care and therefore much underutilised in modern and compromised healthcare settings alike. Many hospital administrators, physicians, nurses, and allied health practitioners still reject maggot therapy due to unfamiliarity, mistrust, or repulsion. There are also regulatory barriers in Ministries of Health which are made worse by a lack of international harmonisation of maggot therapy and medicinal maggot production regulations. Each jurisdiction repeats lengthy and costly regulatory processes that are blocking implementation. On a practical level, maggot therapy places specific demands on the supply chain with respect to rapid delivery and cool chain requirements, which is particularly the case in low-resource compromised healthcare settings. .
My colleagues and I have therefore written A Complete Guide to Maggot Therapy, a book that fills this information vacuum, and makes the current state of knowledge freely accessible to anyone with an internet connection. It is the first book to provide sound evidence-based information beyond the much-discussed therapeutic actions and clinical practice. Particular attention has been paid to the challenges encountered in compromised and low-resource healthcare settings such as disasters, conflict, and poverty. Patients in such settings will benefit greatly from affordable, efficacious, and sustainable maggot therapy. This book is as much a practical guide as it is a summary of the current state of knowledge in the field. The content has been carefully chosen to build global capacity for maggot therapy services including production, distribution, and treatment.
To purchase a hardcopy or digital reader version or to download a free PDF of this book from Open Book Publishers, please click on the box below.
Image: Pinned-Flies-02. Photographer: Emma Leslie. MedMagLabs. Year 2021. CCBY. https://medmaglabs.com/media/