How To Give A Spider A Bad Name
Below is a review of "Envenomation by a spider, Agelenopsis aperta (Family:
Agelenidae) previously considered harmless. R. S. Vetter. 1998. Ann. Emerg.
Med. 32: 739-741." Before getting to the paper, I believe a long overdue
discussion of the terminology dealing with arachnid venom should be covered
first.
Venomous: A meaningless term when used in connection to effects on
humans, since all spiders, except for one of the 106 spider families (Uloboridae,
the hackled orbweavers) and some members of another (Liphistiidae, segmented
trapdoor spiders) and all scorpions have venom. What does this mean? It
means they have venom, so what.
Envenomation: For the medically inclined folks, this seems to mean
a clinically significant reaction by a human to the venom of a spider or
something. It's another meaningless term often loosely applied.
Poisonous Venom: Nobody can decide what this really means. "Poisonous"
implies some toxin that needs to be ingested to affect a human. I don't
think there's many spider eaters out there, except for that South American
tribe that apparently enjoys eating 200 dollar tarantulas on television,
much to the despair of viewers sympathetic towards those poor damn things.
Another worthless term.
Toxic Venom: I think we're getting closer to an accurate description
here, but not by much. "Toxic" can mean a number of things to a wide range
of people. It's not all that acceptable. The word "toxic" is from the Latin
meaning poison (see above).
Potentially Harmful Venom: I don't like this term and neither does
anyone else I know, but it's all we have. The definition of this phrase:
A species possessing venom that has consistently been demonstrated to cause
clinically significant damage to humans, either by neurotoxicity, or by
causing the formation of necrotic lesions. This may not be the most accurate
description, and may change, but it's the best we currently have.
Under this definition, no tarantula species has potentially harmful
venom (despite what many Internet listserver participants believe) since
bite reactions are anything but consistent, and the psychological effects
of the few "reported" bites cannot be separated from real physiological
ones.
In the US, this leaves three groups of spiders clearly meeting the
definition. Loxosceles, the recluse spiders (although not all of the 13
species found so far in the US have had their venom tested), Latrodectus,
the widow spiders (five species in the US), and the hobo spider, Tegenaria
agrestis (Walckenaer). If the nitroglycerin patch treatment for recluse
bites is as effective as some say it is, Loxosceles may need to be removed
from the list of spiders with potentially harmful venom (and more than
likely, the hobo spider as well).
Vetter's paper starts out claiming that it is the first report of clinically
significant bites by this species, [Agelenopsis aperta (Gertsch), Agelenidae,
the funnel weavers] and that it should be considered "a creature of occasional
medical importance."
For evidence, Vetter presented two case reports. In the first, a large
spider was brushed off the neck of a nine-year old boy while in school
at 8 AM in Riverside, California. The spider was collected and later identified
as A. aperta. A mark appeared on the boy's neck, which soon felt rigid
and swelling of the pharynx appeared. This was followed by a headache.
By 1 PM, the boy was taken to an urgent care facility. He had pain in the
muscles and joints of the neck and shoulder and was given a tetanus shot,
some antibiotics, a popular pain killer and was sent home. Before the boy
left, the attending physician told the boy he had been bitten by a brown
recluse spider.
At 7 PM, the "symptoms" had worsened and he was returned to the urgent
care facility. The symptoms included general malaise, pallor, unsteadiness,
heaviness in the legs, a bad headache and tightness in the throat.
Well, excuse me, but does anyone out there think this just might be
a PANIC ATTACK! If I was nine (they tell me I was once, I don't really
believe them) it wouldn't take me anywhere near six hours to begin panicking
after an adult super authority figure just told me I'd been bitten by an
infamous spider, the very name of which can bring stark fear to the seemingly
bravest of adults. Heck, 15, 20 minutes is all I'd need.
The kid was sent home, spent an uneventful night, and had a mild headache
the next morning.
In case report number two, a 54-year old man reached into a pipe to
clear out a spider web and was most appropriately bitten in defense by
the spider being attacked. The thumb swelled and pain was felt. The next
day, the swelling subsided as did the pain. I've had plants nail me far
worse than that.
So much for the evidence, and that's all of it, too. I didn't leave
anything out.
Vetter went on to say various things, how important it was to identify
potentially nasty animals and yadda, yadda, yadda. One thing that stood
out was a curious chunk of missing knowledge concerning Loxosceles. He
stated that only three specimens of the brown recluse, Loxosceles reclusa,
had ever been verified in California (something I didn't know), but then
said no populations of brown recluse had ever been found in the state.
He made it sound as if that species was the only medically significant
one, and didn't mention any of the other Loxosceles present, especially
in southern California. If he had a copy of the ATS recluse and hobo spider
manual, he wouldn't have missed this, but then, if he had a copy he might
not have written this paper in the first place.
The Chilean recluse, Loxosceles laeta, is commonly found in southern
California. This spider is the largest of the recluse spiders found in
the US and is strongly suspected of having the most "potent" venom. The
desert recluse, Loxosceles deserta, is known from central and southern
California. The Arizona recluse, Loxosceles arizonica, is known from southern
California. The Russell recluse, Loxosceles russelli, is known from southern
California. The Baja recluse, Loxosceles palma, is known from southern
California. The martha recluse, Loxosceles martha, is known from southern
California. The Mediterranean recluse, Loxosceles rufescens, is known from
California, most likely in southern California.
In short, California is lousy with recluse spiders; seven of the 13
known species are found there, especially in southern California. This
is more by far than any other state. How did Vetter miss this? It could
have made quite a difference in his paper.
In the last 75 years or so, many workers have tried and failed to implicate
one species of spider or another as a horrible threat to humanity, possessing
terrible, nasty, icky and very ill-mannered venom with poor taste (or maybe
it tasted poorly). Some species of Phidippus (Salticidae, jumping spiders)
and Cheiracanthium (Clubionidae, sac spiders) were implicated as having
potent anti-human venom for a time before being discarded as candidates
due to common sense and non-reproducible data.
Sometimes, workers literally try to scare-up funding by getting the
public excited and demanding the terrible threat be dealt with. Perhaps
the most notable of these occurred with a bark scorpion, Centruroides exilicauda,
in the 1960s' in Tucson, Arizona. The story goes that they needed research
funds, something that's perpetually lacking with most arachnologists. They
began tickling the media's interest with creepy tales of horror that probably
would have done Rod Serling proud.
They raised a ruckus, apparently secured some funds, and did some fine
studies on C. exilicauda. It's too bad they didn't also include Centruroides
vittatus, which some scorpion scientists suspect has venom a little "hotter"
than C. exilicauda. The fund-raising methods may be a little off track,
but C. exilicauda can kill people whose immune systems are absent or damaged,
such as infants, the elderly, people with one or more chronic diseases,
or those allergic (you always have to say allergic, because if you don't,
that one in 156 zillion people this might remotely apply to will immediately
drop dead).
The downside is we now have an intensely feared animal where one didn't
exist before. The scorpion's reputation has been ruined, probably for as
long as humans still roam this planet and can chew gum at the same time.
For healthy folks, the fear of the scorpion will always be far more dangerous
than its actual sting.
I don't believe Vetter wrote the article to drum up funding, but I
also believe there wasn't enough significant scientific material in it
to justify its publication. Had I been a reviewer, I would have rejected
it with no hope of resurrection. The article is published in a journal
read by ER physicians, so it will probably be ignored and won't raise much
of a fuss, even the good parts where he strongly suggests preserving the
spider's body and finding an arachnologist to identify it.
Why was it published?
We all know wasps and bees inflict painful stings. Should we conduct
a census on the possible medical significance of every one of the thousands
upon thousands of species of wasps and bees? Maybe, it would be great fun
for many entomologists.
Would they all be accepted for publication in a medical journal like
this one? Heck no. Almost all medical types know what wasps and bees do.
They are aware of the possible allergic or other reactions or cross-reactions
that can occur with these creatures.
Then why was Vetter's paper published? Because of arachnophobia. Even
the academic medical experts have a fear, uneasiness, or at least a suspicion
of those mysterious spiders and other yucky arachnids. They are willing
to believe the absolute worst with precious little evidence. By publishing
in a journal directed at certain physicians, he likely avoided review by
other arachnologists or other scientists familiar with this field.
So, as for A. aperta, a spider "previously considered harmless," it
is still considered harmless by anyone that has even casually glanced through
this paper.