“During
her hospital stay, a total of 142 larvae were manually extracted, aided by the
application of raw bacon which served as an attractant and petroleum jelly
occlusion.”
You
might be surprised to know that finding interesting articles on infections and
infestations is a thankless and occasionally banal job. It is rare, as you find
yourself trawling through the dusty and dense annals of Pubmed and Jstor, that you stumble upon a really good
paper, the true gold twinkling among the pyrite of multisyllabic articles on
viral proteomics, immunology and dull epidemiological trends in diseases. When
you discover a treasure that renders you mute, like the one I recently
discovered on a screwworm infestation that was wrangled by physicians with
processed pork products, it’s like chancing upon a chupacabra in your backyard.
The sight is both rare and awful, but also mesmerizing to behold. Also, you
need to tell everyone about the chupacabra that you found.
And so
here we are, reader. I found this magnificent article that I need to share out
of scientific obligation, gross-out internet commiserating and out-and-out FYI.
Let’s do this.
In
2007, a 12 year-old girl arrived in an emergency room in Connecticut
complaining of an extraordinary pain in her scalp (1). She had just
returned from a trip to Columbia with her family and speculated that the pain
was due to “sun poisoning.” Previous efforts to diagnose her scalp pain
and what appeared as “fluid-filled bumps” at a local clinic in Colombia identified
cellulitis, a bacterial skin infection, and she was given antibiotics and sent
on her way. Yet the pain persisted and upon returning to Connecticut, the young
patient and her family immediately went to the ER directly from the airport .
It is
disingenuous to simply say that this young girl was in serious pain: to examine
her scalp, to shift the strands of her hair and palpate the affected region,
physicians had to administer intravenous morphine to
bypass her discomfort and suffering. On the right side of her scalp was a
“5×5-cm area of swelling with multiple punched-out lesions oozing a
foul-smelling, purulent exudate (4).” A computed tomography (CT) scan of her
head confirmed the swelling.
The
poor thing underwent “a blunt haircut,” every prepubescent teenage girl’s
nightmare, and “mobile larvae were identified,” every living person on earth’s
nightmare. The larvae were sent to the Connecticut Agricultural Experiment Station and
were identified as the New World screwworm. The Latin name of this bug is Cochliomyia
hominivorax. For those of us rusty on our Latin, “hominivorax” is roughly
translated as “eater of man.”
I know,
I know: there you sit terrified, pondering what kind of world we live in where
scientists could possibly ever think of christening an insect “eater of man.”
It’s a heartless place we live in that plays pranks on you in the form of
flesh-eating insects and I just don’t have an answer that would adequately
explain the slings, arrows and screwworms of daily life. But let me tell you
more about this little man-eater and get this day thoroughly ruined for ya.
The New
World screwworm is an obligate parasite of animals and is a unique brand of
pest in Central and South America where it infects the wounds and mucous
membranes of cattle, sheep and horses (2). Female adult flies lay their eggs
and in 8 to 15 hours the 2-centimeter length larva hatch forth causing
excruciating pain and itchiness. The larva’s body shape is encircled by bristly
ridges along the length of its body, resembling a fat, white screw used to
burrow into living flesh.
This
form of maggot infestation is considered a secondary form of myiasis – the
flies have stumbled upon a human with an existing wound and invade accordingly.
Primary myiasis is caused by the screwworm’s fly cousins and involves a
deliberate breach of skin and tissue by larvae. Secondary myiasis is considered
“generally trivial or even beneficial … [and is] used therapeutically to this
day, because the larvae clean pus and necrotic tissue from difficult wounds
(2).”
Hello there! A close-up of the larva of the
New World screwworm Cochliomyia hominivorax showing its tusklike
mandibles protruding from its mouth which is used to tear and then macerate the
flesh of living warm-blooded animals. Image: Agricultural Research Service of
the U.S. Department of Agriculture. Click for source.
C.
hominivorax can be distinguished from other myiasis-causing buggies by
a traveler’s history and by its propensity to lay hundreds of eggs. Other awful
flies that take this “let’s-infest-this-human” route include the human
botfly, Dermatobia hominis, and the tumbu fly, Cordylobia
anthropophaga (another “eater of man,” incidentally), which tend to
lay a single larva in a wound or lesion (3). C. hominivorax is
the nastier bug of the three: it has cutting jaws that it uses to drill down to
bone and nerves, and enter the bloodstream, necessitating the use of imaging
technologies such as CAT scans and MRIs to see the “extent of larval migration
and proximity to vital structures (1).” The infestation and resulting
infections and abscesses can be deadly; it has a known 8% mortality rate (4).
(In an
extraordinarily clever move, the US agricultural office dealt with the issue of
screwworms in the American South by sterilizing the males with radiation and
then releasing them to mate unprofitably with their female counterparts. The
short lifespan of the females, and the valuable time wasted screwing around
with a sperm-bereft screwworm, quickly eliminated the fly from the North
American landscape (5).)
There
are a few methods to tackle these buggers. One of the treatments is – yes, you
already know, don’t you? – bacon. “Bacon therapy” stems from a traditional
Central American tactic of sorting out human bot fly larvae by jamming pieces
of raw meat or pork into the worm’s breathing hole, known as the punctum (6).
The larvae vacate the premises either enticed by these culinary meat products
or to avoid suffocation by meat, a most ignoble death. As noted in one paper,
it may be necessary to employ “hours of bacon therapy” to entice all of the
infested worms.
Back to
this Connecticut girl’s worst hospital visit ever. Her myiasis stemmed from an
untreated case of psoriasis that had undergone lesions due to scratching; the
female screwworm found an existing wound and a temporary home for her offspring
in the form of this skin disorder. Using a petroleum jelly occusion and bacon
therapy, 142 larvae were extricated from her scalp and she was treated with
antibiotics for an infection of the wound with Staphylococcus aureus. She
was the unfortunate victim of one of the fourth most common
travel-associated skin disease, but thankfully only emerged with scar tissue,
an unfashionable haircut and a helluva travel story (7).
The entire link can be
found at:
http://blogs.discovermagazine.com/bodyhorrors/2013/07/22/screwworm-myiasis/
No comments:
Post a Comment