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 Post subject: brown recluse or hobo spider?
PostPosted: Mon Jan 23, 2012 4:50 am 
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No, not to keep as a pet, but I got to thinking, which one is the worst? I've heard that a hobo spider's venom does the same thing as a brown recluse's, but the brown recluse is the one that always gets the bad rap, and no one knows about the hobo spider. So, which one is more likely to be causing all the damage?


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 Post subject: Re: brown recluse or hobo spider?
PostPosted: Mon Jan 23, 2012 6:04 am 
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I think both have overblown reputations; it's quite likley that a great many "bites" atributed to the brown recluse were caused by other spiders (possibly including hobo spiders) and even insects; and mabe other causes as well. Huge numbers of bites are reported from states where the species is not known to occur. Some of these might be transports, but certainly not all of them. Even the verfied reculse bites don't usually result in the severe necrosis the species is so famous for, it's actually relatively rare.

The sensationalism and tendency towards misdiagnosis concerning Loxoceles make it pretty difficult to answer your question! We have one infamous spider that may not be nearly as dangerous as evertyone thinks, and second lesser known spider that may be more or less dangerous than the othere one.

Wade


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 Post subject: Re: brown recluse or hobo spider?
PostPosted: Mon Jan 23, 2012 4:10 pm 
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Check out this paper on a similar topic, page 158 has a nice list of things which brown recluse bites are blamed for:

http://www.americanarachnology.org/JoA_ ... -1-150.pdf

Christian



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 Post subject: Re: brown recluse or hobo spider?
PostPosted: Tue Jan 24, 2012 5:01 am 
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Christian Elowsky wrote:
Check out this paper on a similar topic....

At a medical entomology conference in Tucson not too long ago Rick Vetter presented a thoroughly entertaining talk on Loxosceles bites. He included statistics on bites that are reported well outside the range where Loxosceles are found. Actually, if he could be induced to do that presentation at an ATS conference I'm sure it woud be very well received.


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 Post subject: Re: brown recluse or hobo spider?
PostPosted: Thu Feb 16, 2012 1:52 pm 
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oh, that would be awesome.


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 Post subject: Re: brown recluse or hobo spider?
PostPosted: Sun Feb 19, 2012 2:52 pm 
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I'm in Northern Virginia where we have lots of Latrodectus mactans and on occasion Latrodectus variolus. The region is considered an outer transition area for Loxosceles. I suspect the majority of reported 'recluse bites' in our area, of which there seem to be many, are supposed rather than documented.

Last year the animal hospital I work for treated a Labrador Retriever for an 'insect bite' that potentially occurred while the pet was in the affiliated boarding kennel. (First of all, I can't imagine any self-respecting spider, or human for that matter, wanting to be around this particular dog for any period of time...) Within 24 hours of admission to the boarding kennel, the patient was presented to the hospital with significant swelling over the hock. Over the next several days the area degraded and much of the skin and underlying tissue sloughed off. Skin grafting was considered, but the wound ultimately healed by second intention over the next 2 months leaving a significant scar. The patient at no time presented with any pain, lameness, lethargy, inappetance, etc. (Considering the dog's general personality was 'Nerve Ending!', it may not have realized its leg was rotting off...)

I have seen Lactrodectus species on the property, but nowhere near the very busy, twice daily disinfected boarding kennel. This patient was not signed up to go on walks and was kept in the boarding kennel proper during his stay, so any exposure to even Lactrodectus would have been minimal to none. Of course the range of differential diagnoses included: Black Widow bite, Brown Recluse bite, spider bite. Final diagnosis was: insect or spider bite.

Any kind of puncture wound can introduce bacteria that can potentially cause extensive cellulitis and deterioration to 'flesh eating' symptoms. (The owner would not approve bacterial or fungal culture, so we have no idea what was growing.) Spiders always seem to be the first suspects even when neither a spider nor a bite is ever observed. The "sensationalism and tendency towards misdiagnosis" is rampant.


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 Post subject: Re: brown recluse or hobo spider?
PostPosted: Sun Sep 29, 2013 10:21 pm 
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I find that any skin lesion of unknown origin tends to be blamed on spiders. The husband of a friend of mine works in landscaping. One night he got home to find a huge lesion on his finger that looked like a gigantic blister. When he went to the hospital, they told him it was a recluse bite (without, of course, a spider body to prove the diagnosis).

After a few days, the swelling began to fade and, lo and behold, they found an embedded stinger.

Last I knew, loxosceles reclusa doesn't have a stinger. Hm... CURIOUS.

I think people have more of a likelihood of coming into contact with the brown recluse than the hobo spider overall, due to territory and preferred living environment.


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 Post subject: Re: brown recluse or hobo spider?
PostPosted: Tue Oct 01, 2013 3:13 am 
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Kiyomizaderu wrote:
No, not to keep as a pet, but I got to thinking, which one is the worst? I've heard that a hobo spider's venom does the same thing as a brown recluse's, but the brown recluse is the one that always gets the bad rap, and no one knows about the hobo spider. So, which one is more likely to be causing all the damage?


I have been trying to find my sources for this info, but have failed miserably, so you'll have to rely on my (failing) memory. (If any of the rest of you can offer references, corrections or embellishments, be my guest!)

Several years ago (maybe a decade or two) some toxicologists someplace did a series of lab studies with hobo spiders on various rodents including rats, mice and guinea pigs. As I remember the bite points were on the inside of the test animals' thighs. Not only did they have a tough time even getting the spiders to bite, but the bites were all pretty much without effect.

So they tried "milking" the spiders and injecting the venom themselves. Zipo! While they had little trouble acquiring the venom, the points of injection never developed the much dreaded lesions.

Citing these results, most toxicologists guardedly declare that all the hubbub about hobo spider bites is probably hysterical misidentification, and that any such "bites" are either from some other arthropod's bite or sting, or some bacterial infection similar to (but not necessarily the same as) necrotizing fasciitis (flesh eating disease).

When you consider the number of such cases reported from places where neither recluses nor hobo spiders have ever been found, it should be a given that, while something is surely causing the problem, most aren't from either spider.

The case isn't closed yet, but it's pretty close.

Peripheral data: While working at John Seally Hospital in Galveston, Texas for a few years I noticed that almost every ranch hand that ever came through our clinical testing laboratory (unrelated to anything approaching either spider bites or bacterial infections) had at least one scar from a recluse bite on their legs. Almost always between the ankle and the knee. The scars were typically about 3" (7.5 cm) in diameter and looked like a round, burn scar. They considered them to be an occupational hazard. Besides, "Chicks like guys with scars!" :lol:


"The magnitude of our ignorance [about spiders] is staggering."
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 Post subject: Re: brown recluse or hobo spider?
PostPosted: Wed Oct 02, 2013 8:27 am 
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The hobo spider (Eratigena agrestis, formerly known as Tegenaria agrestis) is not medically significant, contrary to what some sources say. (Like most spiders, they are technically venomous and are capable of biting in self defense, but they have not been proven to be dangerous to people.)

For recent research, see "Misdiagnosis of Spider Bites: Bacterial Associates, Mechanical Pathogen Transfer, and Hemolytic Potential of Venom From the Hobo Spider, Tegenaria agrestis (Araneae: Agelenidae)" (Click "Free PDF" for the paper.)

Some additional commentary:

Spiders.us wrote:
The "hobo spider," Tegenaria agrestis, is a European spider that has become established in the Pacific Northwest of the United States (and adjacent southern Canada). This species is considered harmless in its native Europe, but there are persistent rumors that the bites of U.S. populations can cause necrotic wounds much like recluse spiders. This has not been reproduced in the laboratory (on humans), so there is no scientific consensus on exactly what is going on here. The findings of the [url="http://esa.publisher.ingentaconnect.com/content/esa/jme/2011/00000048/00000002/art00034"]most recent research[/url] into this matter were published in March of 2011. The study "confirms previous results and provides further evidence that the hobo spider, T. agrestis, is not a spider of medical concern" (Gaver-Wainwright et al. 2011). By thoroughly reading that paper in the above link, you will come to understand some of the reasons that it was ever implicated as a "dangerous" spider to begin with.


Mandy wrote:
Just like the hobo spider, this species was introduced to the Pacific Northwest from Europe. (A side note: the hobo is probably just as harmless here as it is in Europe, and despite all the rumors and misinformation out there, there has actually never been a verified bite by one of them; all the scary "stories" and descriptions of bite symptoms are just assumptions made after some tests were done on rabbits... now everyone is afraid of the hobo without there being any proof that they can or ever have harmed a human, as happens with a lot of spiders. I don't blame anyone for being afraid, though! Some of the websites out there are brutal!)

Around here (Pacific NW), the hobos aren't very big until fall comes around when they are maturing. This time of year, they are still little guys with a leg span about as big as a dime or so. Tegenaria gigantea, on the other hand, can be found pretty much all year round as full-grown adults.


Mandy wrote:
(With websites like hobospider.org still out there, it's no wonder people still fear the hobo. If Darwin Vest were not missing in action (it's generally believed that he is dead :(), I'm sure he'd change his website a lot after the last decade's new research into the hobo and other spiders falsely labeled as dangerously venomous. I've always been thoroughly surprised that he didn't specifically mention that all those "symptoms" of a hobo bite were based on rabbit trials, not human ones. That completely changes everything. Even the photo he uses is likely a random one or that of a brown recluse bite that got bad. There's still no *verified* bite by the hobo ever recorded.)


Mandy wrote:
"Aggressive house spider" is a nickname for the hobo that was given by an entomologist that couldn't speak Latin (just a side note). "Agrestis" is just Latin for "from the fields," it doesn't mean aggressive. Like all the rumors about the hobo and spiders in general, they are made worse by folks that don't really know what they're doing (like someone who doesn't know Latin giving a spider the wrong nickname, and so on).

Research has recently (2011) shown that the hobo's venom does not destroy mammalian cells and that their fangs did not carry bacteria (findings [url="http://esa.publisher.ingentaconnect.com/content/esa/jme/2011/00000048/00000002/art00034"]here[/url]). Who knows what will happen with additional research but, to date, there's been no verified case of this spider biting a human... and all research and arachnological opinion points to it being no more dangerous than any other regular ol' spider. (And if the hobo were established in NY or anywhere else outside of the northwest region, arachnologists would know about it. Things do get transferred around, and that's how the hobo got here in the first place from Europe... but right now there are no established populations in the east.)


Mandy wrote:
While Cheiracanthium were once (as in, in the past) reported to have necrotic venom based on rabbit trials, more recent research has pointed out numerous *verified* bites from that spider in humans and none of them have reproduced necrosis. This has been the same with even the Australian "whitetailed spider," which was constantly blamed for causing necrosis (again, the origin was rabbit trials), yet after a study of 130 *verified* bites onto human skin, not a single one caused necrosis. Same with the "hobo spider," it was induced to bite rabbits and the symptoms were recorded as necrotic. With the hobo spider in particular, there are still no *verified* reports of a hobo biting a human yet (aside from one lady that already had phlebitis, which by itself can cause skin ulcers)... and also with the hobo, recent research (2011) has shown that the venom itself doesn't kill mammalian cells (i.e. is not necrotic). The more we learn and the more time that passes, the more the old, fear-based ideas of the past start to be discarded. Still, there are lots of things no one knows yet.



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