Here is a photo from a make up supplies website Elyse It is supposed to be scary. The concept of maggots eating away at a living person is the stuff of horror films and, as it turns out, science.

In the first world war victims of horrific wounds often went days or weeks without proper medical attention. Wounds were simply bound up and left. William Baer, a surgeon of the time, reports on opening bandages to discover wounds teaming with thousands of maggots. On removing them he discovered dead tissue missing from the wound and only healthy living tissue remaining. Far from causing the death of the unfortunate victims the maggots were saving lives. Maggots only eat dead flesh and they are a most efficient micro surgeon when it comes to cleaning dead and rotting tissue from a wound.

It is a natural characteristic that is once again being harnessed by the medical profession to effectively treat patients with dead and potentially gangrenous tissue. Laboratories are producing blowfly maggots that are free from disease and distributing them to hospitals who use them to treat people suffering conditions that have resulted in extensive tissue death, such as frost bite and burns. The maggots are introduced and the wounds bandaged. Recipients report feeling some movement in the area but not pain from their medicinal companions.

It is, however, a serious departure from the modern approach to medicine and the FDA (food and drug administration) who regulates medicines is having trouble coming to grips with this reintroduction of what is the most ancient of natural surgical techniques. The question is, in legal terms, what are maggots. The FDA's lawyers have decided that they are a medical device since, according to Mark Melkerson, acting director of the Division of General, Restorative and Neurological Devices, speaking of both maggots and leeches

The primary mode of action for maggots is chewing. For leeches, it's the eating of blood. Those are mechanical processes

It seems to The Green Man that both leeches and maggots fall into a category entirely unquantified by the FDA.

Leeches are finding favour amongst microsurgeons charged with the responsibility of reattaching severed bits, such as fingers or hands. The major problem facing these surgeons is the differing structure of veins and arteries. Arteries must be strong enough to handle the pulsing blood pushed out by the heart and, accordingly they are thick walled and easy to identify and reattach. Veins, on the other hand, rely on the movement of muscles in the limb to shift blood back to the heart. Accordingly they are thin walled and difficult to find and repair. This results in a situation where blood is being delivered to the severed limb in greater quantities than it is being recovered, leading to a buildup of blood. This causes swelling and often death of the limb.

Leeches naturally inject patients with a potent chemical cocktail that includes an anticoagulant, an anesthetic, an antibiotic and a substance that dilates blood vessels. This cocktail encourages fast bleeding to empty the appendage of extra blood, reducing pressure and allowing veins to form on their own.

If that wasn't enough, leeches are also extraordinarily sensitive to proper blood flow and so can offer immediate feedback on how well surgery went. Dr. Bruce Minkin, a hand surgeon in Asheville, N.C. says

If it won't attach if there's not good arterial blood coming in, and sometimes that tells me that I need to go back in

The only serious problem in the utilisation of these two excellent biological agents in the treatment of extreme wounds is the attitude of the patients and their relatives. Many find it difficult to conceive that leeches and maggots, both regarded with disgust be most people, can be used in any way that would be beneficial. It is an example where our natural instincts are completely contrary to what is in the best interest of the patient.