# Are yellow sac spiders dangerous?



## windscorpions1 (Apr 16, 2013)

Are yellow sac spiders dangerous? I have looked all over the internet and can't get a clear response. Some people say they are very venomous others say they are harmless. What's the true answer?


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## Rabid538 (Apr 16, 2013)

They aren't anything you have to worry about. The venom is necrotic but it isn't very potent. You might get a blister at worst.
I think people may assume they're very dangerous since they connect necrotic venom with Loxosceles spp. but it isn't anywhere near as bad.

Reactions: Like 2


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## loxoscelesfear (Apr 16, 2013)

*nope, they are not*

Older literature states that yes, yellow sac spiders produce bites similar (though not as severe) to a brown recluse.  Current literature states otherwise: see Vetter 2006 _Verified bites by Cheiracanthium spiders in the United States and Australia: where is the necrosis?  AMER j Trop Med  Hyg 74 _  The same applies to the genus _Trachelas_, and hobo spiders T_egenaria agrestis_of the northwest: they simply aren't dangerous (Hedges, Vetter 2012).

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## windscorpions1 (Apr 16, 2013)

Thanks these replies help me a lot finally I can find an answer.


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## Meezerkoko (Apr 16, 2013)

See this is the problem with common names, there may be a few different spiders that go by the same name, however I've read a few reports (might have been on here) of people who have been bit by them and had chunks rot away or have to be removed, cleaned up and then sewn up.  So your best bet is to avoid them and don't play with them 


Here it is (creeeepy): http://www.arachnoboards.com/ab/sho...um-inclusum-(systemic-amp-poss-allergic-bite)

So yeah.... DON'T PLAY WITH THEM


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## buthus (Apr 16, 2013)

Only the gigantic and/or extra mean ones


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## The Snark (Apr 16, 2013)

From a medical journal morbidity report I read some time ago: "Constrained or encapsulated dermatological incident *resembling* necrosis in a small number of bites that were positively identified being from Cheiracanthium " No, I don't recall which report. There are probably 100 to 1,000 morbidity reports published every day. 

I stumbled into this debate some time ago. From the research I did the conclusions drawn of the bites were essentially similar to significant wasp stings with the above occasionally noted. One very significant part of the medical journal reports by physicians is physicians use the word 'resembling' a lot. This doesn't mean it is; the doctor is simply categorizing. However, lay persons like to take such wording and use it as a substantiated fact. With physicians reports, 'resembling' is only a surmise to give the lab techs and forensic pathologists a heads up as to what to look for. Necrosis can be venom or trauma induced but the actual chemical-biological reaction where a loss of vascularization with insidious properties, true foreign object/material necrosis, is extremely difficult to properly identify.

One trauma doctor summed up all the myths, legends and gibberish to me regarding necrotic venom: "It isn't unless it is and overwhelming evidence points to the latter. With the yellow sac spider the jury is still out and probably won't be back any time soon. As far as I'm concerned it's a hefty wasp wallop."


A brief explanation of the necrosis issue. I'm going to use some pretty graphic wording so be forewarned. Necrosis is simply tissue death. Many living organisms with a full functional vascular system, heart, lungs, aeteries and veins, have the ability to devascularize, arrest blood flow, both locally and systemically. Commonly referred to as shock. The neurological system sends out signals that shut down the plumbing. The veins collapse and blood flow is arrested. In a minor incident this is noted as redness and localized swelling. The cause can be external force, traumatic of nature, or invasive, foreign object, or both. The concern is the tissues and bones are no longer receiving oxygenated blood. With blood flow restricted the innate resistance the body has to infection, yellow blood cells etc., is reduced or even eliminated. Bacteria can enter the injury and cause further damage.
With the body able to restrict the blood flow all by itself, finding an external cause for the loss of vascularization as a venom means that the venom must be extracted from the injury, separated from all other body fluids and foreign material and a chemical analysis is performed that positively identifies the venom is present and it triggered the loss of blood flow. To give a rough analogy, you have a 500 gallon back yard pool filled with assorted soups, excrements, bacterias, blood and body organs, and you as a lab tech are trying to find 1/10th of a cubic centimeter of a certain exotic chemical in that soup. If it can't be found and positively identified, it doesn't exist. Something else started the chain of events leading to tissue death.

To exacerbate the necrotic venom issue is the problem that necrosis is self regenerating. Once the blood flow has been cut off and bacteria invade the tissues, the body will expand the blood flow restriction on it's own, trying to prevent the dead cells and bacteria from spreading through the body -going systemic. Necrotic venoms are contributors to this process but usually not the main cause. The body itself is inhibiting the blood flow.

How effective is the body at restricting blood flow all by itself? Very. A limb can be severed completely from the body and little or no blood loss, even from severed arteries, may be noted. So if a body can do this all on it's own, and bacteria is constantly getting into a wound that can caused devascularization as well, how can you positively identify a venom is also present which is promoting the bodies vascular restriction mechanisms? For frosting on the cake, necrotic venoms don't cause blood flow to slow or stop. They only induce it and the body, normal neurological and vascular reactions keep the necrosis cycle going. And bacteria invading the tissue can also act as a necrosis inducing agent.


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## Smokehound714 (Apr 19, 2013)

IMO, yellow sac spiders are no more dangerous than any other common spider.

  Ive noticed their venom affects me nearly identically to a fire-ant sting.


  Alot of "necrotic" bites are actually because the victim scratches incessantly, causing infection, and therefore severe necrosis.

  Those people probably never wash their wounds (or bodies lol) making it even worse.


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## Ciphor (Apr 19, 2013)

Smokehound714 said:


> IMO, yellow sac spiders are no more dangerous than any other common spider.
> 
> Ive noticed their venom affects me nearly identically to a fire-ant sting.
> 
> ...


Probably not that easy to diagnose the cause of an ulcerated wound turning necrotic in any case. If it was easy, there wouldn't be so many misdiagnoses even today.

The good news is we are always learning and finding out new things. Modern research shows this spider and the hobo along with a laundry list of other spiders (white tail spider, steatoda, etc.) are no more dangerous than a bee sting minus the allergic reaction. Something key we learned, is people can react different to different toxins, and some animals are capable of carrying pathogens which can lead to a more severe or completely different reaction then you would expect under normal conditions.

That being said, the yellow sac spider is considered by most experts who _study in this field_ to be no more dangerous than 99% of the spiders on earth. Just because a few people had a bad reaction doesn't mean most will.


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## The Snark (Apr 19, 2013)

Doing research, it appears that there has been only one fully identified and documented yellow sac spider envenomation that has had a significant pathological effect involving necrosis. Vetter UCR, reporting. http://web.archive.org/web/20090210012443/http://spiders.ucr.edu/dermatol.html
At present, it is disputed that this spider has the known necrotic agent sphingomyelinase D. It may possess a different and yet unidentified agent or the known incidents of bites involving necrosis may have had the necrotic agent become involved as a secondary infector such as a bacterium.

So far, this spider has been proven to be more hazardous to certain Mazda cars than to humans.


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