The yellow sac spider - an investigation

[NYAN]

Hi all, I’m sure that many of us have heard about the yellow sac spider, genus cheiracanthium. In this latest investigation of mine, I want to figure out how severe the yellow sac spider’s bites really can be, but mostly debunk the myths about them in an organized way. This spider has been regarded as being medically significant and being the cause of necrotic lesions in humans. I come to assert that this is erronus though. I welcome bite reports from people here as well as scientific articles.

To start off, we have this article from WSU entomology department: http://entomology.wsu.edu/outreach/bug-info/yellow-sac-spider/

This article offers an opposing view, which I was quite interested in. It seems to be outdated because it mentions the hobo spider in a way that one would infer it is harmful to humans.

This next source describes 20 confirmed bites (spider was collected and identified). None resulted in any necrosis. These confirmed bites took place in Australia and the United States across a period of a couple of years. This source also does a good job listing the symptoms patients experienced and how often they were shown.

https://www.researchgate.net/public...ed_States_and_Australia_Where_is_the_necrosis

In this short summary, we have another confirmed bite from a cheiracanthium species. No necrosis was reported.
Thanks to @lostbrane for this one

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1512058/?page=1

Here we have another article which describes two confirmed bites from cheiracanthium species. This article presents a report from a man in and his daughter in Italy who were both bitten, but experienced no necrosis or any severe symptoms. Both were treated at the hospital and symptoms disappeared after a couple of hours. The spider was protecting her egg sac which resulted in a bite.


This article summarized a ‘suspected’ bite in Italy. The man experienced a very extreme reaction which was attributed to being from a yellow sac spider. The conclusion that a spider bit the man came not from a spider being captured in the act of biting the man. This conclusion was made only on the assumption that because the locker room the man was in was ‘infested’ with spiders, one must’ve bitten him. These same conclusions were made in the erroneous claims of Darwin Vest regarding the hobo spider. This case cannot be considered a confirmed bite, despite infection and fasciitis being ruled out.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2923970/

Here we have an article written by arachnologist Rod Crawford on the burkemuseam website. This article offers a summary of some of the information mentioned beforehand, but also explains the backstory of the belief that the yellow sac spider causes necrosis. That belief comes from tests done on guinea pigs which developed necrotic lesions. We can draw more parallels to the hobo spider from this, which was also demonized because of tests done on rabbits that yielded similar results. In the rabbit test, no sterile conditions were used and there was no control group. Perhaps the same happened in this experiment.
http://www.burkemuseum.org/static/spidermyth/myths/innocents.html


Now, with so little evidence of these spiders being dangerous or possessing the ability to cause necrosis in humans, why do we still hear about yellow sac spider bites and why is there still fear? The answer to this question is in the medical community and the general public, who may report erroneous information from a position of authority to people who do not know better.
IN PROGRESS:
MORE ARTICLES WILL BE ADDED

 

[lostbrane]

From the few articles I just read it seems C. inclusum bites are equated to that of a bee/wasp sting (this was before I found the bite report). They didn't provide a source for that. As to the necrosis, the article you posted about it seems to nip that myth in the bud.

Here's a bite report from 1957: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1512058/?page=1

 

[WildSpider]

Hi all, I’m sure that many of us have heard about the yellow sac spider, genus cheiracanthium. In this latest investigation of mine, I want to figure out how severe the yellow sac spider’s bites really can be, but mostly debunk the myths about them in an organized way. This spider has been regarded as being medically significant and being the cause of necrotic lesions in humans. I come to assert that this is erronus though. I welcome bite reports from people here as well as scientific articles.

To start off, we have this article from WSU entomology department: http://entomology.wsu.edu/outreach/bug-info/yellow-sac-spider/

This article offers an opposing view, which I was quite interested in. It seems to be outdated because it mentions the hobo spider in a way that one would infer it is harmful to humans.

This next source describes 20 confirmed bites (spider was collected and identified). None resulted in any necrosis. These confirmed bites took place in Australia and the United States across a period of a couple of years. This source also does a good job listing the symptoms patients experienced and how often they were shown.

https://www.researchgate.net/public...ed_States_and_Australia_Where_is_the_necrosis

In this short summary, we have another confirmed bite from a cheiracanthium species. No necrosis was reported.
Thanks to @lostbrane for this one

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1512058/?page=1

Here we have another article which describes two confirmed bites from cheiracanthium species. This article presents a report from a man in and his daughter in Italy who were both bitten, but experienced no necrosis or any severe symptoms. Both were treated at the hospital and symptoms disappeared after a couple of hours. The spider was protecting her egg sac which resulted in a bite.


This article summarized a ‘suspected’ bite in Italy. The man experienced a very extreme reaction which was attributed to being from a yellow sac spider. The conclusion that a spider bit the man came not from a spider being captured in the act of biting the man. This conclusion was made only on the assumption that because the locker room the man was in was ‘infested’ with spiders, one must’ve bitten him. These same conclusions were made in the erroneous claims of Darwin Vest regarding the hobo spider. This case cannot be considered a confirmed bite, despite infection and fasciitis being ruled out.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2923970/

Here we have an article written by arachnologist Rod Crawford on the burkemuseam website. This article offers a summary of some of the information mentioned beforehand, but also explains the backstory of the belief that the yellow sac spider causes necrosis. That belief comes from tests done on guinea pigs which developed necrotic lesions. We can draw more parallels to the hobo spider from this, which was also demonized because of tests done on rabbits that yielded similar results. In the rabbit test, no sterile conditions were used and there was no control group. Perhaps the same happened in this experiment.
http://www.burkemuseum.org/static/spidermyth/myths/innocents.html


Now, with so little evidence of these spiders being dangerous or possessing the ability to cause necrosis in humans, why do we still hear about yellow sac spider bites and why is there still fear? The answer to this question is in the medical community and the general public, who may report erroneous information from a position of authority to people who do not know better.
IN PROGRESS:
MORE ARTICLES WILL BE ADDED

Cheiracanthium are one of the few kinds of true spiders that I'm actually nervous about. They were one of the very first spiders I started to research when I was first started getting interested in this hobby. Online I found probably everything you're trying to figure out whether or not is true including how aggressive they are. The reason I looked them up is there were a few living in my room at the time and I was watching them hunt at night.

I've thought a few times that this is probably silly though as these have been in our house my entire life and I don't think I've ever even been bit by a spider (let alone this one). Funny thing is, my mom actually likes them despite my fear .

I will be interested in seeing if this fear is unfounded. I would like not having to panic whenever I see this genus.

 

[NYAN]

Online I found probably everything you're trying to figure out whether or not is true including how aggressive they are.

I don’t believe that any spider is really aggressive. Sure you have phoneutria and a few others which are very defensive, but aggressive to me means that they will chase you down and attack for no reason. I’ve handed sac spiders without issue. They mainly want to get away.

I've thought a few times that this is probably silly though as these have been in our house my entire life and I don't think I've ever even been bit by a spider (let alone this one). Funny thing is, my mom actually likes them despite my fear .

I will be interested in seeing if this fear is unfounded. I would like not having to panic whenever I see this genus.

Your fear is most likely unfounded. There’s no evidence to suggest these spiders are medically significant.

 

[WildSpider]

I don’t believe that any spider is really aggressive. Sure you have phoneutria and a few others which are very defensive, but aggressive to me means that they will chase you down and attack for no reason. I’ve handed sac spiders without issue. They mainly want to get away.

That's exactly what aggressive means to me too. In fact, I decided to use the word aggressive instead of defensive for this very reason as that's the feeling I got from the internet. The fact that they will let you handle them to me is already 1 step toward me getting over this . Thanks!

Your fear is most likely unfounded. There’s no evidence to suggest these spiders are medically significant.

Glad to hear it!

I've actually kept them anyway despite this feeling and I think that's been helping too.

 

[lostbrane]

One thing that keeps popping up is that some people react differently with some species bites. I'm wondering what sort of sensitivity they might have, that would cause more severe reactions.

 

[The Snark]

Just to point out a small elephant in the room. In all the reports where necrosis was noted, whether a spider bite or not, each is described as lesions. The word lesion is very vague and can refer to a half dozen different things or more. Injury, wound, ulcer, abscess, tumor, disease, boil, eczema, psoriasis, dermatitis and a few more. Of note, many of these conditions involve a degree of necrosis. Necrosis simply being dead tissue. This quite a long distance away from persistent, pervasive, malignant dermal necrosis as caused by a necrosis causative agent.

From what I am reading in all those links is poorly or devascularized lesions. No positive potent necrosis inducing agent is indicated anywhere. Devascularization, which is the commonest cause of necrosis, is normal in many different kinds of wounds and conditions. IE, ain't no gun, smoking or otherwise, to be seen.

 

[Chris LXXIX]

Here's my bite report (C.punctorium):

http://arachnoboards.com/threads/cheiracanthium-inclusum-systemic-poss-allergic-bite.68817/

 

[Greasylake]

With some of these less medically significant spiders sometimes I have half a mind to let them bite me so I can give a purely objective bite report, but I don't really want to become Coyote Peterson so I probably never will.

 

[NYAN]

Just to point out a small elephant in the room. In all the reports where necrosis was noted, whether a spider bite or not, each is described as lesions. The word lesion is very vague and can refer to a half dozen different things or more. Injury, wound, ulcer, abscess, tumor, disease, boil, eczema, psoriasis, dermatitis and a few more. Of note, many of these conditions involve a degree of necrosis. Necrosis simply being dead tissue. This quite a long distance away from persistent, pervasive, malignant dermal necrosis as caused by a necrosis causative agent.

From what I am reading in all those links is poorly or devascularized lesions. No positive potent necrosis inducing agent is indicated anywhere. Devascularization, which is the commonest cause of necrosis, is normal in many different kinds of wounds and conditions. IE, ain't no gun, smoking or otherwise, to be seen.

Just to point out a small elephant in the room. In all the reports where necrosis was noted, whether a spider bite or not, each is described as lesions. The word lesion is very vague and can refer to a half dozen different things or more. Injury, wound, ulcer, abscess, tumor, disease, boil, eczema, psoriasis, dermatitis and a few more. Of note, many of these conditions involve a degree of necrosis. Necrosis simply being dead tissue. This quite a long distance away from persistent, pervasive, malignant dermal necrosis as caused by a necrosis causative agent.

This is actually a good point which I am aware of. The term lesion is pretty vast indeed. As for necrosis, it simply means the death of tissue. I suppose I should replace necrosis with necrotic lesions.

From what I am reading in all those links is poorly or devascularized lesions. No positive potent necrosis inducing agent is indicated anywhere. Devascularization, which is the commonest cause of necrosis, is normal in many different kinds of wounds and conditions. IE, ain't no gun, smoking or otherwise, to be seen.

Are you referring to the 19 year old Italian man?

 

[The Snark]

I note something interesting with the various suspect bite reports. All of them. The venom went systemic and produced a broad spectrum immune system response. @boina could explain and detail this much better than I.

Are you referring to the 19 year old Italian man?

Maybe. I speed read all the reports and they got glopped together.

 

[NYAN]

I note something interesting with the various suspect bite reports. All of them. The venom went systemic and produced a broad spectrum immune system response. @boina could explain and detail this much better than I.

Well, I referenced 20 bite reports where nothing major occurred to the patients and 3 more where nothing happened. I’m aware that venom can effect each person differently and it’s pososble sometbing like a sac spider could cause a more extreme reaction than normal. However, we see an absense of confirmed bites to prove this. I remember reading reading notes from a the first team of researches who published the summary of the 20 reports, and they mention only knowing of a single case where a lesion developed, and it was described as a small one. Yes, I know, there’s that word which can be amything.

 

[The Snark]

Did some rereading here. Purely unscientific. Intuition mode and general savvy. There have been enough confirmed and suspected bites to draw some basic conclusions.
- cheiracanthium does pack a reasonably potent but non lethal venom.
- The venom tends to go systemic and triggers typical immune system responses. Nausea is a good solid indicator.
- Envenomation symptoms have never lasted longer than 4 days. Another sign it's gone systemic and the body has done it's normal thing evacuating the toxins. No urological or hematological symptoms reported.
- There hasn't been any reports I've read where severe problematic symptoms have been reliably repetitiously reported: Respiratory distress, acute chest pains, cardiac arrhythmia or notable neurological effects as termors, numbness, eyesight issues, disorientation, dizziness.
- Indications of the venom being necrotic, actually inducing progressive necrosis have not been reliably reported where clinical intervention was required.

So, lacking solid clinical evidence to the contrary, the spider venom is down at the potentially significant nuisance level but isn't potent enough to warrant specific clinical treatment procedures or investigation into the production of an antivenin.

In conclusion, the venom has triggered a strong immune system response in many reported bite incidents. Therefore, it could be conjectured that the necrosis, 'lesions' that have been reported, which have differed significantly from each other, were in fact immune system responses which have been observed clinically to emulate all of the presumed necrosis indications.

 

[boina]

Very interesting thread . I just learned here that there are actually idiots that consider(ed) the completely harmless Eratigena 'medically significant'. For some reason this fear driven response to declare every idipathic 'lesion' a spider bite seems more prevalent in America than in Europe, but in general this stems from complete arachnological ignorance in the medical prefession.
Example: I found exactly one German medical site that discussed spider bites. They cite Eratiga agrestis, and only agrestis, as medically significant with bite reports only from the USA. Since bite reports are only from the USA and not a single one from Europe they declare E. agrestis to be an American spider and rare in Europe... no, guys, E. agrestis is originally from Europe and is one of the more common spiders around here, so that argument doesn't cut... still, the medical toxicologists believe that nonsense, because why else would the Americans have so many bite reports and the Europeans haven't?

Back to the original topic: After reading about Eratigena I'm not surprised that the moderately more venomous sac spider gets blamed for all kinds of stuff, too. Dear @The Snark , when it comes to 'systemic' reactions there's one thing I'd like to mention: Systemic reactions are few and rare and very unspecific, as in headaches and nausea. Now, how about coincidence? Got bitten by a spider and got an unrelated headache? Or, how about a psychosomatic reaction: Got bitten by a 'venomous' spider, panicked, and felt nausea and threw up? I wouldn't be so quick to cite an immune reaction in those cases. The one clear immune reaction I found was one case of urticaria after a bite in the face - and in this case I'd want further information before I believe in an allergic reaction due to a spider bite. Quite a lot of topical antibiotics are known to have the potential to cause urticaria whereas spider bites do not... was an antibiotic cream applied in this case? Or a cooling gel with the potential for allergic reactions? It's never as clear cut as spider bite -> every symptom that follows is due to spider venom.

 

[The Snark]

and only agrestis, as medically significant with bite reports only from the USA.

So the US is polluting science the world over. But we already knew that.

Or, how about a psychosomatic reaction: Got bitten by a 'venomous' spider, panicked, and felt nausea and threw up? I wouldn't be so quick to cite an immune reaction in those cases.

I'm doing my best to play devils advocate here. Be gentle.

I suppose my entire diatribe should have been prefixed, "Being grossly generalized and presuming worst case, psychosomatics, Anaphylaxis (I hope you noticed how I neatly danced around that one), congenital diseases and defects, chronic conditions, genetic traits and defects and an assortment of other debilitating conditions notwithstanding... "

Being brutally honest here, there is no smoking gun. The spider has a weird venom that can kicketh yer butteth somewhat when circumstances and conditions are right and your bodily functions are wrong, but overall this whole yellow sac spider-necrosis thing is yet another sensationalist mountain from a molehill. Innocent until proven guilty beyond reasonable doubt.
The doubting debaters who have been chomped by them are welcome to dance nekkid on a hornet hole then compare the two.

 

[NYAN]

Did some rereading here. Purely unscientific. Intuition mode and general savvy. There have been enough confirmed and suspected bites to draw some basic conclusions.

Which articles are you referring to as being unscientific?

- cheiracanthium does pack a reasonably potent but non lethal venom.

I can agree with this, but how potent is the question. Surely not latrodectus potent, but maybe steatoda potent

- The venom tends to go systemic and triggers typical immune system responses. Nausea is a good solid indicator.
.

I’m not sure about this, and boina does make a good point about coincidences.

- There hasn't been any reports I've read where severe problematic symptoms have been reliably repetitiously reported: Respiratory distress, acute chest pains, cardiac arrhythmia or notable neurological effects as termors, numbness, eyesight issues, disorientation, dizziness.

I’ve read none of these reports either in cases of confirmed bites. I don’t think the spider is capable of causing any significant symptoms in a regular healthy human.

- Indications of the venom being necrotic, actually inducing progressive necrosis have not been reliably reported where clinical intervention was required.

From what we know, there’s is no reliable evidence that their venom alone can cause necrotic lesions to form. It’s all imagined it seems.

So, lacking solid clinical evidence to the contrary, the spider venom is down at the potentially significant nuisance level but isn't potent enough to warrant specific clinical treatment procedures or investigation into the production of an antivenin.

I agree. I wouldn’t consider cheiracanthium to be totally harmless, but it isn’t definitely not medically significant. I wish we could have a larger understanding about what kind of symptoms can be generally expected from the venom.

 

[The Snark]

wish we could have a larger understanding about what kind of symptoms can be generally expected from the venom.

Has there been an analysis of the venom?

 

[NYAN]

Has there been an analysis of the venom?

I don’t believe so, but I haven’t checked.



I found this article which seems promising http://www.jbc.org/content/early/2010/07/24/jbc.M110.104265.full.pdf

 

[The Snark]

@NYAN Something just occurred to me. many, most or nearly all spider venoms contain components that have digestive properties. Surely some of those components would produce an effect that in outward appearance if not in fact is necrotic?

 

[NYAN]

@NYAN Something just occurred to me. many, most or nearly all spider venoms contain components that have digestive properties. Surely some of those components would produce an effect that in outward appearance if not in fact is necrotic?

That’s correct that they do. However, would the digestive components be effective on humans, or mammals in general for a large amount of species?