after 2-3 failures of conventional medical or surgical therapy, especially
those which are infected or contain dead tissue. Only a few species of
fly larvae, primarily blowflies (Calliphoridae
: e.g. Lucilia
sericata (a.k.a. Phaenicia sericata, sheep blowfly, green
bottle fly)), are suitable for such duty. 5-10 maggots are placed on each
cm2 (0.2 in2) of a wound, which is then covered with
a protective dressing that allows the maggots to breath. For the next 48
to 72 hours, the maggots dissolve dead tissue by secreting digestive juices
and then ingesting the liquefied tissue and bacteria. Beneficial effects
upon a chronic nonhealing wound include removal of necrotic tissue ('debridement'),
disinfection of the wound and active promotion of granulation tissue formation.
As a major cellular component of granulation tissue, fibroblasts play an
extensive role in healing. The maggots grow from about 2 mm (0.08 inch)
to nearly 10 mm (0.4 inch) while doing the doctor's dirty work. Wounds
commonly treated include foot and leg ulcers (including diabetic ulcersref1,
ref2,
ref3),
burnsref,
and post-operative wounds that have become infected and re-opened and have
lingered for months or even years. Some maggots burrow deep into living
flesh, but the ones we use recycle organic waste : in nature they go for
naturally decomposing material and not living tissue, competing successfully
with bacteria, even with antibiotic resistant strains—as long as the environment
is to their liking. Most patients feel nothing during treatment, but some
do feel tickling or itching, like a crawling on the skin. A few patients
have described discomfort or outright pain once the maggots become large,
probably due to them crawling over nerves or squeezing into tight crevices.
Pain is controlled with simple pills, or the maggots can be removed early
and the pain disappears immediately. By the second and third day the wound
oozes, becoming a bit sloppy and smelly. However, the process never lasts
more than 72 hours. Other than such minor concerns, the treatment has yet
to produce many, if any, serious negative reactions. The medical potential
of maggots was first seen in Central Africa, when some patients brought
in from the bush had survived for days without treatment because maggots
kept their wounds clean. But maggot medicine has older roots and its wound-cleansing
ability has been noted on battlefields for centuries. In the 1920s and
30s, before the advent of effective antibiotics, maggots were often used.
Military surgeons in the First World War saw people come in from no man's
land, where they'd been for perhaps days : the ones who were still alive
had maggots in their wounds and they hadn't died of gangrene or infection
because the maggots in their wounds had mopped up the bacteria. Since 1995,
the number of practitioners using maggot therapy has increased not only
in the U.S. and U.K., but also in Germany, Scandinavia, Ukraine, and the
Middle East : there have been at least 25,000 treatments in the U.K. during
the last decade. There is little commercial value in the maggots, and not
enough financial support to conduct the necessary clinical trials. A woman
with perforation of the bowels and an infection that had spread through
the abdomen, causing death (gangrene) of her bowel wall and peritoneum
needed dead tissue to be removed every other day in a risky surgical procedure
: 2,000 maggots were sprinkled over her open abdomen, and then covered
with a dressing and 2 days later the maggots were washed out, revealing
no more gangrene. Apart from iatrogenous secondary
myiasis,
the crucial technical problem of biosurgery is asepsis of the larvae :
with Protophormia
terraenovae Providencia
stuartii
and Candida albicans
bloodstream infections occurred in 21%, but with Lucilia
sericata no case of sepsis has been detected with bloodstream infections.
With an appropriate disinfecting procedure, maggots free of pathogens can
be obtained. Provided the maggots have been effectively disinfected, their
application on chronic ulcers seems to be safe.Web resources : BioTherapeutics Education and Research Foundation (BTERF)
