This is probably the most common medically significant spider in the world

[c'est ma]

(Apologies if this has already been posted...)

"This is probably the most common medically significant spider in the world"

http://tachinid.wordpress.com/2009/01/12/this-is-probably-the-most-common-medically-significant-spider-in-the-world/

( http://tinyurl.com/7lc39k )

--Diane

[bhoeschcod]

I dont think its been posted:confused:

[gvfarns]

Hmmm. It was news to me. Thanks for posting.

[What]

Im going to say right now that I think the "study" is mostly bs. There are far more Steatoda bites that go unreported or undocumented simply because the majority of people will not have any major or noticeable effects from the venom.

That is like saying that Scolopendra polymorpha is medically significant. Or doing the same thing with fleas and people that have allergies to them. Just because some people have allergies to something which results in a medically significant reaction doesnt mean that the venom should be classed as such...

[lucanidae]

This is how easy it is to turn a generally innocuous and common species into 'The most common medically significant spider in the world'.

Fact: The Yellow Sac Spider, Cheiracanthium mildei, is extremely common in homes and apartment buildings across the US and Europe.

Fact: The bites of Cheiracanthium species sometimes lead to necrosis and other side effects.

Insert arm waving to support the point here.

References:

Foradori et al. 2005. Survey for potentially necrotizing spider venoms, with special emphasis on Cheiracanthium mildei. Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology Volume 141, Issue 1.

Furman and Reeves. 1957. Toxic Bite of a Spider, Cheiracanthium Inclusum Hentz. Calif Med. Aug;87(2):114

What does common even mean in relation to Steatoda grossa? Common as an average across the US or the world? Latrodectus is extremely common in some parts of the world. It isn't uncommon to find neighborhoods full of houses that contain thousands of brown recluse in the United States. Sure, this species is common. But the MOST common of any spider recognized as sometimes potentially having medical consequences associated with its bite?

Don't believe the hype.

[jsloan]

It's unfortunate that it costs $37 to download the complete report from which this information is taken for the blog. I'd like to read the original article, but it's too expensive.

[jsloan]

There are far more Steatoda bites that go unreported or undocumented simply because the majority of people will not have any major or noticeable effects from the venom.

Where are you getting your information about these undocumented reports, unless they have been documented? That is, how do we know this is a fact? It's not a very convincing argument against a scientific study that reaches the opposite conclusion based on documented cases and an analysis of the venom (according to the abstract).

[lucanidae]

Spider bites are notoriously difficult to diagnose...even if the spider is brought in the medical community is prone to mis-identification. The fact of the matter is that most spider bites do nothing and probably go unnoticed. It stands to reason that the majority of bites caused by species commonly found in houses would go unreported. You don't go to the ER for a bruise or a headache. Same thing with the majority of these bites, they tend to be minor and last less than 24 hours.

[c'est ma]

My, my, are some of us feeling just a bit contrarian today? :D Anyone notice the "probably" in the title?

I didn't think the blogger's intent was necessarily to make an airtight case for his title thesis so much as to point up the misperceptions about spider "danger" in general...but maybe I was feeling just a bit too mellow when I read it...:)

--Diane

PS: I also thought his funnel-web post had the same sort of hysteria-calming intention:

Don’t you wish you were in Australia?
http://tachinid.wordpress.com/2009/01/10/dont-you-wish-you-were-in-australia/

(And that he had some nice pictures here:

Uaraneida and the origin of silk in spiders
http://tachinid.wordpress.com/2009/01/05/uraneida-silk/#more-439)

[lucanidae]

From the bottom of 'Don't you wish you were in Australia'

Next week, I’m going to show you the world’s most common medically significant spider. You have them in your house. You’ve seen one, there’s no doubt about it. I can guarantee you’ve never heard of it.

I just doubt everyone has seen one. I've also heard about it before. And this clearly states it is the world's most common. The premise of this as 'the most common' simply has nothing to stand on. If the blog entry was something to the effect of 'You probably didn't suspect this', which I assume was the intent...it would have been a little easier to swallow the rest of it.

[c'est ma]

Spider bites are notoriously difficult to diagnose...even if the spider is brought in the medical community is prone to mis-identification. The fact of the matter is that most spider bites do nothing and probably go unnoticed. It stands to reason that the majority of bites caused by species commonly found in houses would go unreported. You don't go to the ER for a bruise or a headache. Same thing with the majority of these bites, they tend to be minor and last less than 24 hours.

And from the article:

"Usually, spider bites don’t require any sort of treatment. The bites are either dry or just not noticed, and this guy [the Steatoda] is no different. "

[jsloan]

Spider bites are notoriously difficult to diagnose...even if the spider is brought in the medical community is prone to mis-identification. The fact of the matter is that most spider bites do nothing and probably go unnoticed. It stands to reason that the majority of bites caused by species commonly found in houses would go unreported. You don't go to the ER for a bruise or a headache. Same thing with the majority of these bites, they tend to be minor and last less than 24 hours.

I understand. According to the abstract, though, this study looked at bites where the identity of the spider was confirmed by an expert. So, this is different from what you're talking about.

I do agree that most spider bites are harmless. It would seem, though, that given the information in this study, S. grossa bites are not always so.

[lucanidae]

I'm not really concerned with Steatoda's venom potential. Though I still think labeling it as 'medically significant' is laughable. Peanuts are medically significant too, since a small portion of the population has a deadly reaction to them. Really, this logic makes anything medically significant. What really gets me is this 'most common' stuff.

It simply has no data to back it up. Worldwide distribution? Comparable to Latrodectus and many others. Sheer numbers or diversity of habitat? Maybe. We aren't told, and I really don't think it's a good thing to be spreading around qualifiers like 'most common' with nothing to back it up.

[c'est ma]

You win.

(...Lengthening my post to at least 10 characters...)

[jsloan]

I just doubt everyone has seen one. I've also heard about it before. And this clearly states it is the world's most common. The premise of this as 'the most common' simply has nothing to stand on. If the blog entry was something to the effect of 'You probably didn't suspect this', which I assume was the intent...it would have been a little easier to swallow the rest of it.

I'm not going to dismiss a scientific study (not talking about the blog here, but the referrenced article). S. grossa may very well be significantly venomous. However, I know they are not prone to bite. I did a paper on this spider about 30 years ago while at Oregon State University. For about 6 months I observed them in the wild and also in the lab. I even handled them. Never got bitten. These spiders, like Latrodectus, are more prone to run than attack.

The same goes for Steatoda paykulliana, which I studied for a couple of years in Iran, and which are also reported as being venomous. In those days I caught many of them by enticing them out of their hideaways by throwing a bug in their web. When the spider came out I reached down with my hand and scooped it up. I did this many times and was never bitten. [Note: I do not recommend that others try this, however, given the toxicity of Steatoda venom.]

So, I'd say let us not be quick to dismiss the results of a scientific study, which seems to have followed proper protocol; but at the same time, we know that just because a spider is venomous it is not necessarily dangerous, given its reluctance to bite. I think this is what the blog is trying to say as well.

[jsloan]

Worldwide distribution? Comparable to Latrodectus and many others. Sheer numbers or diversity of habitat? Maybe. We aren't told, and I really don't think it's a good thing to be spreading around qualifiers like 'most common' with nothing to back it up.

If you're talking about the genus Steatoda itself, I think it does have a worldwide distribution. I do know that the species S. grossa is found in parts of both North America and Europe. I'm not sure where else it might be. I guess I'll do some googling. :)

[Drachenjager]

im wondering what species it is that I have never heard of lol
anyway.
I think that if you check under my house you will not find any S. grossa. however you will find very very many L. mactans. so as for me and my house that article is baloney lol

[lucanidae]

A couple questions in this thread got me interested, so I spent some time googling. I found some more support for my hypothetical suggestion that sac spiders are the 'most common' medically significant spider.

From the Colorado State Department of Entomology Extension Office:


Sac spiders are active hunters. They get their name because they spend daylight hours in a flattened silken sac, typically located in the upper corners of rooms or in wall cracks. Most sac spiders are pale colored. They are usually the most common spider found wandering in homes during fall, particularly at night. Cheiracanthium species are suspected as being the most common source of spider bites in homes.

http://www.ext.colostate.edu/pubs/insect/05512.html

By: F.B. Peairs, W.S. Cranshaw and P.E. Cushing

Colorado State University Extension entomologists and professors, bioagricultural sciences and pest management; and P. Cushing, curator of entomology and arachnology, Denver Museum of Nature and Science. 12/96. Revised 12/08.

[Cheshire]

The post was simply meant to compare the incidence of bites of a spider famous for being venomous to one which most folks wouldn't associate with being highly toxic to make the point that a lot of hysteria over arachnidism is over reputation and not incidence. I can guarantee you that outside of the bug community, very few people know what Steatoda is.

So...let's look at what I actually said, versus what people seem to think I said. I'm pretty certain nobody read that post or the article cited.

From my post:

Usually, spider bites don’t require any sort of treatment. The bites are either dry or just not noticed, and this guy is no different. However, in a minority of cases the symptoms are severe.

So...yes. I pointed out that the majority of bites are unreported by saying they're not noticed and/or don't require treatment. I also mentioned that only the minority of bites needed treatment. This is also stated quite plainly in the article I cited.

I even conclude:

Now…the reason I’m telling you this isn’t so you can freak out and be all like ZOMG! Teh spydrz r envading! and convince you to go out and bug-bomb your garage. That would be stupid, because the spiders you killed would simply be replaced in a matter of days.

Instead, what I’m attempting to do is to give some perspective to spider bite incidence and show people exactly how dangerous spiders really are. In the popular media, spiders and other insects are often elevated to the status of bears, sharks and lions (who also get screwed over as a result of popular perception) when in reality, there are more mundane things which kill people in areas where medically significant spiders are found.

I then go on to point out the similarities between Latrodectus and Steatoda venom in both electrophoresis studies and physiological effects because they are similar and to state anything else would be intellectually dishonest. I also mention that many bites of this species are confused with those of black widows.

In the article, only confirmed bites in which the spider collected was used. The spiders were properly identified and any cases where the spider couldn't be ID'd (IIRC, there was one which was crushed beyond recognition) were discarded from the sample. Only people who sought medical attention were sampled for the study, and the paper went out of it's way to point out that no symptoms were reported in the majority of the sample.

I can quote the methodology here if you like.

As for my definition of common...well, the fact that these guys are commonly found in close association with humans does fit the bill as being 'common'. They have a far wider distribution than Loxoceles or Atrax. I could probably say the same thing about Cheiracanthium mildei and still be equally as correct. I didn't use a definitive term in that post...I did inadvertently in another.

In the post about Atrax robusta...I'll conceed you're right that I did use a blanket statement where I shouldn't have. I'll post a retraction for that in a few moments, and I'll happily post a retraction of anything else in that post which is shown to be false through primary literature.

This is the type of writing people here always complain about being absent from popular science writing. Well...here it is. You've seen it and you're still looking for reasons why it's too alarmist. It's an article about why spider bites aren't that big of a deal written from the prospective of an entomology student who used primary research to make the point.

Find something factually wrong and I'll post a complete, public retraction. However, I am not going to post a retraction over the fact that a few people get pissed off over the fact that somebody on the internet pointed out that spiders occasionally hurt people. To deny this is intellectually dishonest-I won't stand for it. In the post, I did go out of my way (which many people here have pointed out) to de-emphasize the medical importance of spider bites.


Oh...and just in case anybody wasn't aware of this, that's my weblog. I am normally a denizen of TWH and started the blog so I could write about biology without clogging up AB.

It's nice to see I'm going back full circle.

[Cheshire]

Lucanidae...just out of curiosity, what do you make of this (http://www.ajtmh.org/cgi/content/abstract/74/6/1043)?

We're getting into toxicology now...not exactly my specialty.

[c'est ma]

LOL, and I didn't even know you (Cheshire) were on AB! Guess we non-TWH AB'ers are really out of it...

Bet I've seen you in Pharyngula comments, tho!

[What]

Where are you getting your information about these undocumented reports, unless they have been documented?
The 3 bites I received from S. grossa whilst working in my yard last year were not reported, so from just my isolated case(and my neighbors) I could probably come up with ~20 more bites in the same time span the article claims from the reference(1999-2002). And those are all spiders I am confident on the ID about, something that I doubt was present in the study.(Take "brown recluse" bites for instance, more than a handful of other spiders (http://dermatology.cdlib.org/DOJvol5num2/special/recluse.html) have been identified by "experts" as recluses.)

That is, how do we know this is a fact? It's not a very convincing argument against a scientific study that reaches the opposite conclusion based on documented cases and an analysis of the venom (according to the abstract).
How about Hobo spiders and the paper that concluded they produced dermonecrotic lesions?(Vest, D. K. (1987). Envenomation by Tegenaria agrestis (Walckenaer) spiders in rabbits. Toxicon 25(2):221-4.)

I think we all know how that turned out... Just because something is submitted and published as a peer reviewed paper doesnt mean the data is correct.

[lucanidae]

Like I said before, I'm really not concerned about whether Steatoda is considered 'medically significant'. And, like I said earlier, I still think it's laughable that anyone would call it that. Peer-reviewed papers who refer to it this way are at worst using it as a ploy for funding/publication and at best are simply vastly overstating the danger of this genus. But that really dosen't matter.

Here are the top google results for 'medically significant spider' and how they mention Steatoda:

http://en.wikipedia.org/wiki/Spider_bite#Types_of_spiders_with_medically_signif icant_venom

Mentions them as having minor effects.

http://www.royalalbertamuseum.ca/natural/insects/research/dangspid.htm

No mention in relation to venom.

http://spiders.ucr.edu/dermatol.html

Mentioned only because of their similarity to Latrodectus and some reports of minor bites.

I also didn't say anything about your presentation as being over-the-top. I've been in that situation; I was interviewed about P. murinus and gave what I thought was the best information available, yet when the article hit the web AB members tore into my analysis (which I still stand by..except the parts that were altered by the newspaper). I don't think your article is fear mongering at all. Still, when you put things out on the internet, and especially when they are linked here...people are going to question your assumptions.

What I do suggest is that this qualifier of 'most common', or the slightly less exact 'probably most common' is incorrect and shouldn't be used. This is the case because you provide nothing to say in what sense it is common, and there is no data to back it up as being 'the most common' in any sense other than possibly worldwide distribution. Even if it were... whether or not it is 'medically significant' comes into question. I've also provided quotes from entomology professors and arachnid museum curators showing that sac spiders, which have been considered medically significant for some time, are "the most common spider found wandering in homes during fall" and "the most common source of spider bites in homes."

I did read the paper you cited. I also sent PM's offering it to others in the thread who couldn't get their own copy for free.

As for the other paper you linked, it's part of the ongoing argument about spider bites. You can find similar papers for the effects of hobo spiders and for brown recluses. If this Steatoda rumor lasts long enough, you'll see similar papers about them too.

[jsloan]

I can guarantee you that outside of the bug community, very few people know what Steatoda is.

Which is true for about 99% of any spiders you care to name. I'd say that even most entomologists don't know much about spiders and wouldn't know what Steatoda is. When I was at Oregon State U. (majoring in entomology) I took a class taught by an entomolgist whose speciality was systematics. He was the currator of the insect collection there. He knew every insect in the book, but not a thing about identifying spiders, not even to family. I know, because the spider section of the university arthropod collection consisted of a single jar of miscellaneous spiders. He showed it to me and I immediately saw several families, genera, etc, where he just saw a bunch of spiders. Later, I separated them out and labelled them for the collection.


I'm pretty certain nobody read that post or the article cited.

I believe you'll find that my posts agreed with your basic message. I "got" what you were saying.

This is the type of writing people here always complain about being absent from popular science writing. Well...here it is. You've seen it and you're still looking for reasons why it's too alarmist. It's an article about why spider bites aren't that big of a deal written from the prospective of an entomology student who used primary research to make the point.

Frankly, I've been enjoying your blogs, but I'd prefer a straighter presentation of information, and a less "popular science" style of writing. That's speaking only for myself, of course. I understand that it isn't easy to write science articles, even in the popular style, so I'm reluctant to be any more critical than that. Keep writing, whatever you do.

[Cheshire]

Yeah...there are problems using certain lab animals for clinical studies.

In an amusing but demonstrative case, a harmless
South African wandering spider Palystes natalius (Sparassidae)
was incorrectly deemed potentially dangerous to humans because the experimental bite by a live spider to the
nose of one guinea pig caused death; in subsequent research
using anesthesized and conscious guinea pigs, researchers
concluded that death was probably due to fright, not venom
toxicity.

I'm really trying to act as a PR person for spiders/other insects here. If I'm wrong on anything-point it out. Factcheck me. It doesn't do anybody a favor if I'm spewing nonsense.

[jsloan]

Just because something is submitted and published as a peer reviewed paper doesnt mean the data is correct.

Point accepted. However, was that paper on the hobo spider rejected simply out of hand, or was it because of later information or studies? If later studies cast doubt on these current S. grossa studies, I'm all for going where the facts lead us. It seems to me, though, you are rejecting this study too quickly. Apparently, some S. grossa bites do have serious effects, yours notwithstanding. That's all I'm saying. Is it possible that you only received dry bites?

Even if the study is correct, I don't think S. grossa is dangerous. I've handled it many times and have never been bitten. In fact, I have been studying spiders for 40 years, have handled thousands of spiders, and I have never been bitten, not once. So, I'm fully aware that spiders do not bite readily. Mind you, I know which ones do tend to bite, and how to handle spiders in general.

At any rate, it is good that we are trading points and not barbs here. This is a purely technical discussion, IMO, with nothing personal about it. :)

[Cheshire]

That is a ridiculous assumption. I believe you'll find that my posts agreed with your basic message. I "got" what you were saying.

Aaaah...sorry. I tend to charge in riding high on my work, especially when I don't think folks have tried to glean the meaning. You've seen what I write about (Uranaeida, for example) and you can probably guess the type of thing I normally encounter.

Got a little pissy...but there was a legitimate problem with the post.

Frankly, I've been enjoying your blogs, but I'd prefer a straighter presentation of information, and a less "popular science" style of writing. That's speaking only for myself, of course. I understand that it isn't easy to write science articles, even in the popular style, so I'm reluctant to be any more critical than that. Keep writing, whatever you do.

This is something I'm attempting to work on. I'm trying to write in a style that draws in people who may not be interested and create an interest. It's a common argument against popular science magazines, but now I'm writing from the other side of the fence and I'm starting to see a bit of how this sort of thing can be problematic. It's a bit difficult...and I think this will definitely help me in the future.

I've posted the title's retraction.

[c'est ma]

Still, when you put things out on the internet, and especially when they are linked here...people are going to question your assumptions.


Humble apologies, Cheshire! I'll never link to you again!...:wall:

[Cheshire]

No worries...Lucanidae pointed out a minor mistake and I corrected it after arguing my point.

You should see what goes down in TWH.

;)

Really...link me as much as you want. I try to write stuff I'm proud of and writing stuff which isn't an accurate representation of the current research isn't much use to anyone.

[c'est ma]

When I was at Oregon State U. (majoring in entomology) I took a class taught by an entomolgist whose speciality was systematics. He was the currator of the insect collection there. He knew every insect in the book, but not a thing about identifying spiders, not even to family.

Dr. Lattin? Ever take a course from Nagel? :)

No worries...Lucanidae pointed out a minor mistake and I corrected it after arguing my point.

Whew!


You should see what goes down in TWH.

;)

Hmmm--tempting. :D

Really...link me as much as you want. I try to write stuff I'm proud of and writing stuff which isn't an accurate representation of the current research isn't much use to anyone.

Will try to read you often, but must warn you I can't even keep up with all the SB sites I like...AAACK, the blogosphere is too rich & crowded to follow! I'm behind! I'm behind! (If only we didn't have to sleep!)

--Diane

[jsloan]

Dr. Lattin? Ever take a course from Nagel? :)

This was in the mid 70s, a long time ago. I can't remember the guy's name, but I don't think it was Lattin. Sorry, but Nagel doesn't ring a bell, either. The only name I remember right now was Dr. Christopher Bayne in the Zoology department, who looked over that paper I wrote on S. grossa. Also, David E. Hill, who was my principal advisor on that paper. He was working on his masters degree at the time, on the structure of the central nervous system of Phidippus. If I remember the name of the curator I'll let you know.

[c'est ma]

This was in the mid 70s, a long time ago. I can't remember the guy's name, but I don't think it was Lattin. Sorry, but Nagel doesn't ring a bell, either. The only name I remember right now was Dr. Christopher Bayne in the Zoology department, who looked over that paper I wrote on S. grossa. Also, David E. Hill, who was my principal advisor on that paper. He was working on his masters degree at the time, on the structure of the central nervous system of Phidippus. If I remember the name of the curator I'll let you know.

PM-ing you so my hijack doesn't get any worse!

--Diane

Edit--Hey, wait. Can I hijack my own post? :D

[Dark Raptor]

Fact: The Yellow Sac Spider, Cheiracanthium mildei, is extremely common in homes and apartment buildings across the US and Europe.

Fact: The bites of Cheiracanthium species sometimes lead to necrosis and other side effects.

Necrosis is a very, very rare situation.
More information about Cheiracanthium bites:
Vetter and all. 2006: VERIFIED BITES BY YELLOW SAC SPIDERS (GENUS CHEIRACANTHIUM) IN THE UNITED STATES AND AUSTRALIA: WHERE IS THE NECROSIS? Am. J. Trop. Med. Hyg., 74(6), 2006, pp. 1043-1048

Fasan and all. 2008: Spider Myths and a Case of a Bite by a Yellow Sac Spider. The Journal of the American Board of Family Medicine 21 (1): 78.

I think you will find this table very interesting:
http://img83.imageshack.us/img83/2305/tabel1qg0.jpg
Source: Ibister G. K., White J. 2004: Clinical consequences of spider bites: recent advances in our understanding. Toxicon 43 (2004) 477–492

[Cheshire]

Yeah...I'm just going to re-tool that post and make more which include some other species, mostly focusing on the effects of the venom. Don't worry...I'll be far more careful in my wording this time around.

After re-reading that post, I kind of concluded that it communicated something I didn't intend (this includes phrasing which wasn't pointed out by Lucanidae), so I'm going to re-work it. I generally don't write a whole lot of medical stuff, so this is kind of new to me.

Basically...post = FAIL

In the meantime, there's another paper on auto-post set to go off.

Phasmids...not spiders this time

[Venom]

I'm with Lucanidae on this one. I don't see Steatoda as deserving of the "medically significant" status. Their potency is not an issue, and their size...lol. I'm usually the first to ring the caution bell...but I don't see Steatoda being an issue. The most one could realistically expect from this species is a few itchy, red bumps. Anything else, while a possibility, is such an outlier as to place these beyond concern.

Cheiracanthium, however, is still under-rated. In my observation, envenomation by this species commonly results in strong local swelling and inflammation, pustulation, and intense, radiating pain. I have personally seen a case in which, after four ( 4 ) bites by a C. inclusum, to the instep and side of the right foot, the victim was unable to walk for three days, requiring a crutch. Fever, nausea, and headache are common with this species. Systemic ( or even intense local ) symptoms are NOT the norm with Steatoda bites.

In my opinion Cheiracanthium > Steatoda, in terms of envenomation significance.

Cheshire...you must understand what is meant by "necrosis." Basically, there are two things that can happen with Cheiracanthium spp. envenomation:

Scenario A:

Intense, immediate pain. Bite area swells, and becomes strongly red/ purple. Area becomes highly sensitive to touch, and severely painful. Mild fever, chills, and nausea may coincide with the local symptoms. Blister forms in the approximate center of the bite. After a few days, it recedes, along with the swelling and pain. Victim feels better after 1 - 3 days, local symptoms gone after 1 week.


Scenario B:

Intense, immediate pain. Bite area swells, and becomes strongly red/ purple. Area becomes highly sensitive to touch, and severely painful. Mild fever, chills, and nausea may coincide with the local symptoms. Blister forms in the approximate center of the bite. After a day or two, this bursts, forming a shallow crater in the center of a swollen boil. This may continue to ulcurate and inflame, taking several weeks to fully disappear. Scar remains.

ONLY SCENARIO B is described as involving "necrosis," or, an open, tissue-degrading sore. The first scenario, which involved a CLOSED blister, is not considered "necrosis," despite the intense pain, severe local swelling, and accompanying systemic discomfort. Scenario A is the most common form of Cheiracanthium envenomation, with open boil/ pit necrosis occuring much less often. However, the incidence of Scenario A's effects, as opposed to the
incidence of systemic Steatodism, is far greater in frequency and probability.

Despite what *may* take place in a Steatoda envenomation, Cheiracanthium's effects have a higher incidence of actually happening, and are just as severe, if not more so, IMO. All in all, I'm much more comfortable considering Cheiracanthium spp. as "medically significant," than I am with Steatoda spp.